Canting Keels In Production Yachts

[D'ARTOIS]

The last post in the "Sydney Hobart" thread were highlighted by some facts stated by Mistral and Lorsail.
Lorsail commented to tell us that already a number of canting keels have been integrated in production design.
Although I visit expositions regularly, I haven't seen any system manufacturer for example on METS in Amsterdam, neither on Hiswa, and I am curious if they are represented on the next show in Dusseldorf, coming week.
It must be clear that Lorsail, Mr Lord, represents a company that is connected to the manufacturing c.q. promotion of canting keels and any criticism on canting keels and/or its mechanism, concerns him professionally.

We have to accept the fact that the canting keel technology does have specific advantages over the traditional keel configuration. That it is first applied in racing yachts is not more than logic. Any advance technology that is not ruled out will be welcomed and most happily applied.
That this newly applied technology (however old in theoretical principle) has been met by many pro's and contra's is a result of regular sketpiticism in an old fashioned trade as yachtbuilding certanly is.

However, and I would like to revert to what Mr Lord stated, that this - in my personal opinion rather undeveloped technology, new or old is unimportant, is showing up in production boats that are sold to the general public, who is unaware of the full extend of their purchase.

Or, the application of the canting keel on an yacht outside the racing community is an individual application and carried out on an individual demand. Or, more precisely, the canting keel happens to be mounte on so called "one off's" - individual made boats to individual designs.

The next question is, since insurance plays a vital and elementary role in the US community (and in a lesser degree to the European) is it desirable to apply this still fresh technique being not fully developed yet - to have the CK's applied to production yachts.
The more, since the insurance issue is not clear yet and the CK (as far as I am aware of) has no CE certification, or there are no yachtseries yet in Europe that are already CE certified with a CK applied.

[Gina22]

http://www.cbtfco.com/wrapper.php?page=pages/schock40.html

http://www.santanasailboats.com/boats/schock40/schock40.htm :cool:

[Doug Lord]

D'artois: saying I represent a company that is using canting keels is NOT true-yet. I build radio control models along with full size prototypes. I intend to build -but do not yet build- a radio control one meter model using a canting keel.I've also built and sailed almost a dozen radio controlled canting keel models strictly as test prototypes over the last ten years.I can assure you that that is a labor of love not money!
I am not connected in any way with any full size company doing canting keels. I MAY build an 18' canting keel boat as a prototype to test various concepts in the application of canting keels to small boats.
I believe in the technology NOT because of any business interest but because I have studied it carefully and have had the privledge of discussing various aspects of the technology with some top people in the industry.
This technology has proved itself many times over and will continue to do so. It is the fastest keelboat technology bar none and has brought monohull keelboat performance into a new age. In fact the evolution of this fantastic technology is a long way from over with canting keel hydrofoils borrowing from the Moth style foil setup being tested in rc models by me and I know others on the west coast are actively looking into this untapped potential. Canting keels on hydrofoil equipped boats will also provide extra stability by the use of a flap on the lower portion of the canting fin/strut. Very exciting !
I think there is great potential for the application of this technology to cruising boats and the one I mentioned in Sail magazine is being built by Stimson or Stinson Yachts in the UK. Interesting design where the daggerboard for the extra lateral resistance is BEHIND the canting keel.
I'm not at all familiar with whether or not any standards organization(Lloyds, ABYC,EU) has developed any recommendations for canting keels but I'm sure they will and think they should...
I think arbitrary rules such as the 10° static heel rule in Open 60's and mini's (and the Sydney Hobart) is probably not the best solution and has led to some trully weird hull shapes.

[D'ARTOIS]

Lorsail, I fully accept the advantagious design of the CK / CBTF let that been noted. I know that this technology will develop rapidly and that the racing people will come to use this (valuable) addition to racing technology widely. Reading the Schock pages I discovered that it could lead to a dramatic reduction of keel ballast, a very important improvement that I did not realise at first sight.

It is fully comprehensible that the smaller racing yachts do much more profit from this technology than the 60 ft + racing machines.
First of all, the example of the Schock 40. This is not what I understand as a regular yacht design, although, technically speaking, it is.
It comes not even in the cruiser-racer category.
The Schock 40 is whay we call over here "a fun boat" - a clubracer, daysailor,
very well engineered for this purpose. This yacht however is an on purpose build racing machine and stands therefore outside the scope of the thread.

Just as in car racing, some of the used high tech applications are adapted from the race courses to the general designs, to the production boats. Mostly improvements in hull design, hull-manufacturing, ruddersystems etc.
In general, the buyers of the today's production boats have or have had some profit from the investments done in the racing field. And more to come.

The advantages of materials like the aramids ( I am not mentioning any brand names) epoxies and other fibers/resins, were industrial developments creatively adapted for the use in yacht building technology. Of course, this is the result of the efforts of the industry in general.

Now the canting keel. The technical advantages are known and accepted. That the bigger boats still struggle with the technology is not so important. My question is: what might be the use of this technology for the normal cruising boat, for the family boat, immaterial length or make, now or in the immediate future.

[brian eiland]

THREE QUESTIONS FOR RUSSELL BOWLER
Russell Bowler, president of Farr Design, was questioned by mail for an
article about the next Volvo Ocean Race published in the French magazine
Course Au Large. Here are his answers:

1. Which are the main improvements in the design of Volvo 70s compared to
the old generation of WOR 60 ?

RB: VOR70 was conceived as the fastest 70ft ocean going monohull employing
the latest performance enhancing features. While only 4ft longer than the
VOR 60, the VOR70 has deeper draft, canting keel, 50% more sail area at
the same sailing displacement. Construction technology is full carbon
sandwich construction and has abandoned the impact resistance of Kevlar
laminates required by the V60 rule. Rule minimum shell weights for the
hull, deck and watertight bulkheads prevent the structures from being
frail. Rig height and sail area give the required horsepower to make the
VOR 70 a high speed ocean racing yacht. The overall result is a boat that
will be potentially 33% faster than the VOR 60 and a big challenge for
designers, builders and sailors.

2. Can you compare one of your last Volvo 70 design to your Open 60 design
for Jean-Pierre Dick ?

RB : Open 60 rules and the VOR 70 rules are very different in their basic
format. The Open 60 Rule encourages wide boats because the heel with
ballast fully canted by rule can not exceed 10 degrees, which has type
formed this class. The VOR70 rule has a cant angle limit, restricted rig
dimensions, minimum bulb weight and upper and lower displacement limits.
Common to both rules is the freedom to use any variety of appendages to
make the boat perform, although there are some limits in the VOR 70 rule.
With both projects we put a big effort into providing the sailors with an
appendage package (canards and rudders) that would provide good balance
and sea keeping qualities over a broad range of sailing conditions that
can be expected in long distance ocean racing. Research into this subject
had some useful overlaps for the two designs. Single handed sailing has a
different focus on rig operation than the fully crewed VOR 70. Both
projects however are fast, light displacement ocean going yachts that
share some development characteristics

From SeaSailSurf.com:
http://seasailsurf.com/seasailsurf/actu/article.php3?id_article=3480

Farr Design website : http://www.farrdesign.com
Course Au Large: http://www.courseaularge.com

[Gina22]

Hi,
Another links

http://www.backmanboats.com/

http://www.tboat.com/

http://www.cariboni-italy.com/HOME.html
... they are fast sailing boats, fast daysailors or fast sportboats not for coffee boil.
Faster then boats with fixed keel


Gina 22

[Gina22]

Sorry I have forget:
http://www.balticyacht.com Baltic 78 and Baltic 56
in thet ships may bie to boil your coffee

Regard Gina22

[D'ARTOIS]

The Backman is a "Fun Boat" and a dayracer.

2. According to Baltic, only the 56 is in an early stage of design to be equipped with a CBTF - that's the twin foil system from - or according - to Dyna Yachts design.

3. Caborini offers indeed a remarkable design: the combined lifting- and canting keel, again, only pratical in large non-production yachts.

You continue to refer to racing yachts. As I clearly stated before, they are not included in this topic. Neither do the non-production yachts.

[mistral]

mmmm, not a plenty of boats, considering that backman 18 is still on the drawing board and Baltic 78 and 56 won't sell a grat numeber of boat (quite expensive and luxury yachts); that confirm what i wrote in another thread.
Cariboni is a great producer of hi-tech fittings parts, with some awesome solutions such as "magic trim", but he doesn't produce boat at all.
I guess ten Schock 40 are sailing now; so, where are the big numbers???? I cannot see any production boat with decent numbers of purchased boat in this list....

Mistral

[Doug Lord]

Numbers will come ,Mistral and the publicity of being without doubt the fastest monohull keel technology in history won't hurt.
Plenty of things stil to try yet to such as low aspect ratio canting keels for dedicated shallow draft cruisers, boats under 20' etc,etc,.....

[D'ARTOIS]

What I try to establish is Mistral, that outside the racing field and a number of top dollar yachts, the CK cannot be found elsewhere.
Any references given sofar were about racing yachts, by the way, the Backman 21 is a reality and sails already, but outside the racing scene it seems that no other yacht is fitted out with the CK.

However, what we have learned is that the main advantage of the canting keel is the fact that you may either increase your sail-area with 50% or drop the same percentage of ballast, and any mix of the two in between.

In this respect has Lorsail all the right of the world when he states that it is a dramatical improvement of sailing technology level because a 50% increase of sailarea at the same ballastratio that is no cat's piss.

What I am afraid of is, that yachtracing is now factor X more expensive. Take my word for it that now I have seen Cariboni's frame and further machinery to make this keel system working, that in two or three years time all serious racing yachts will have this keel fitted. No doubt about that.

Very interesting for the very few designers in the field of the big racing yacht's the maxi racers; ( not mentioning any names ) because one of the most well known fetches per design, for the Volvo Open among others, more than USD 1 mil per boat. Emphasize the word more.

[B. Hamm]

I think the technology is just too new and in some circles untrusted for a production designer to risk it. You have to remember that it's very expensive to put a boat design in production. If the technology isn't accepted, you at minimum have to partially retool to get any return on your investment.

Couple other problems:

1) like water ballast was a few years back, there have to be some accepted limits to the canting angle, if the machinery fails you still need to be able to return to port. Perhaps a combination of the canting keel and another form of shiftable ballast?

2) all of this takes up space in the hull that could be used for accomodations, or at minimum storage. Don't know what the public's reaction will be to giving away space in a given hull. I suspect though that with many fairly modern designs that cruisers would rather have the accomodations than an increase in speed. Some percentage though might accept it, how large that percentage is though is the question.

Bill H.

[Gina22]

The most of Vendee-Globe constructions have canting keel and water ballast tank also. The abandonned ships have returned to port with decreased sails, and with fully water ballast on the luv, slowly then racespeed.
I think one-ramming system is not enough, all elevators have emergency break.

The rules over canting keel from ISAAF is not old. (Raceboating)

In an charter yacht, typically 40-44', i's not enough space for technic. But if you will with an minimal, family crew to sail, it is the best. For me is an american daysailer, or clubracer for 2 weeks my Home.

Gina22

[D'ARTOIS]

Mr Hamm, you hit the nail on the head, and you too Gina, and that's exactly why I started this thread. The design will probably remain in, and be limited to, the racing scene and in top dollar yachts where there is sufficient space for this equipment.

It will have no use for the everyday's sailor, whose ship is too small, and who doesn't have the financial sourcing.


For the rest, well if anybody should know how difficult it is to get something new from the ground, it's be me. Watch my next thread!

[Gina22]

Mr Hamm 15 years ago was CARBON for space-research, today more
mast builder are working on serie carbon masts.
Any yachts with DECK salon, like Jeanneau 43 DS, or with centrecockpit can have enough space for this technic.
The question is the thriftiness of market.

Regards Gina22

[D'ARTOIS]

You should address me because I answered you and not Mr Hamm.
Can you forward a practical design to back your reply up?

[Doug Lord]

If you look at the installation of the canting mechanics in the Schock 40 you can see that they take up minimal space. If you look at the design published in Sail the designers comments were that the boat was a 60 footer with the room of a well appointed 50 footer.
Part of the problem ,in terms of room , on canting keel designs applied to cruising boats is the choice of extra lateral resistance. There are two recent options that eliminate the extra lateral resistance as a "room" problem: fixed wings and retractable bulb/keel wings. Fixed wings have been thoroughly proven on boats like Atomic designed by Andy Dovell in Sydney Australia. kFOIL™ retractable wings have yet to be proven but show great potential.
These solutions can be adapted to low aspect ratio canting keels so that the boat can have a shallow draft in addition to some of the other benefits of canting keels.
Another area wide open for the application of canting/retracting keels(and wings for convenience) are small boats under 20 feet where the canting system is part of the overall righting moment with the crew. The canting keel can allow more performance with fewer crew making a boat that would "normally" be triple handed double handed or a boat that would normally be double handed single handed. These small boats can offer performance closer to an unballasted dinghy then a "normal" keelboat while retaining the advantages of the keel.
Canting keels are not limited to just racing boats by any technical limitation -or any other limitation. They haven't even come close to being used for every application they're suitable for...

[D'ARTOIS]

Up to a certain degree I am with you. However, I prefer to stay in the range of 35-45 ft boats overall, being the most bought dimension.

The reference to the Shock is indeed something to consider however you forgot that the Shock is a gutted out light displacement design and not the heavier type cruising boat that needs sturder equipment and at least a good designed frame to get a solid basis for the keelsuspension. In the Schock the provisions could be slim because of the low ballast weight.

I still say it not very practical because the addition of a foil to increase the lateral surface is an option that the general cruiser certainly wouldn't like. We have pretty shallow waters here that are often fould up with plastic bags et.
Secondly, such a device is another added riskfactor for undesriable damage.

You must make a clear distinction between not possible and not practical.
There is need for extra electrical power - one of the week spots in any sailing yacht ( I sail regularly from Holland to France, 2000 nm open sea, so don't
tell me anything about electricity on a medium sized yacht).
You have another sensitive mechanical - electrical device in your boat, that needs extra electricity and charging on top of your regular (electrical) requirements - and that is already difficult to maintain.

What I will do however is to ask one of the most well known sailing magazines
in Holland to give me some space for an item on this subject. So we will learn
from say 30.000 - 40.000 sailors how they think about this subject.
And what the pro- and contra's are according to their opinion.

[B. Hamm]

For an offshore boat, and with a canting keel I'd assume that's where it would be used, there is no such thing as extra space. Storage and tankage space is at a premium on all designs. Something has to be given up to add the space for the keel shifting mechanics.

The problem I'd have with these designs is the requirement to make it fail safe would take up alot more room. I'm sure for a coastal cruiser it can be done, not sure though it makes sense on a boat designed for extensive cruising.
Bill H.

[mistral]

i think the key-concept is completely different from saving inners space for this stuff.
I'll try to sum-up some ideas:
-Canting keels will never have success in cruising production sailboat as long as they're seen only as a way to improve performance.
-as a matter of fact, the first point is that canting keels improve righting moment, let's ty to focus on this point.
-improving righting moment, canting keel can make a boat quite more stiffer (less heeling) and therefore more comfortable and safer, almost for poorly experienced sailor.
-that is the ONLY way canting keel's technology may be promoted in production design: we have to demonstrate that it leads to have safer and more confortable boats!!!
Of course this means a bullet-proof engineering of all the mechanical parts!!!
but you have to think that for cruising boats weight is not a dramatic issue as for racing ones, so you can slightly downsize the bulb (considering that you'll cant it) and invest a part this saved weight in a really sturdy redundant canting device; in this way you'll get:
-a stiffer and safer cruising yacth
-a shallower all-canted keel, allowing you to enter more easily in little marinas
-a lighter or (at least) same weight cruising yacth with better comfort and probably slightly better performance.

Mistral

[SeaDrive]

IN MY OPINION, the advanced technologies of canting keels, carbon fiber and the lot are going to have a depressing effect on the cruising sailboat market. As they drive up performance, they also increase cost, complexity, crew requirements, and crew knowledge requirements. In the racing classes, this is acceptable and expected, though not really desireable.

But when Mr. & Mrs. Cruiserperson go out to buy a boat, they find that a boat which they can afford and can sail by themselves is much, much slower than the racing boats they read about. Pride of ownership is hard to maintain when your max speed is 7 kts, and the boat in the next slip has a max of 20 kts. The fact that the boats were built for different purposes and different use profiles does not make up the psychological gap.

Back in the days of the CCA, a racing boat had about the same potential as a cruising boat. Perhaps less, since the cruiser was not constrained by the rule. So you can see the situation has changed markedly in the last 40 years. The performance gap has been steadily increasing due especially to high performance, high cost sail cloth, and designers' use of speed enhancing but cruiser unfriendly features such as deep draft and very light displacement.

[mistral]

ok, so let's ban F1 car, they make me feel slow in my little citycar, let's ban multihulls 'cause they make me feel slow on the water, now that i don't sail hobie16 anymore, let's ban boats bigger than 30 feet 'cause they outsail my dinghy upwind, furthermore let's break a leg of Bode Miller, Herman Mayer and all those guys who skys downhill at 60 mph, they make me feel very sloooooooow on the snow; and what about jet planes, Ferrari, Lotus, BMW cars, fast japanese motorcycles and all this speedy stuff?????????
:) :) :) :) :) :) :) :)

There are prices that you have to pay to sail fast, if you think they're worth to be paid you can get a sport multihull or a new design monohull for a decent budget, otherwise get a good cruiser boat and relax sailing, while racers will be overstressed managing their rocket-boats trying no to break anything ;) ;)

Mistral

[SeaDrive]

ok, so let's ban F1 car, they make me feel slow in my little citycar, ...

I didn't suggest banning anything; I made a prediction. Here is another: although the canting keel has brought multihull speeds to monohulls, I predict that multihulls will be more popular than canters as cruising boats over the next several decades.

[mistral]

I didn't suggest banning anything; I made a prediction. Here is another: although the canting keel has brought multihull speeds to monohulls, I predict that multihulls will be more popular than canters as cruising boats over the next several decades.

multihulls keep on going six-eight knots faster than monohull :)
anyway you are right about canters and multihulls, multis are growing in popularity, while canters are still on the limbo of hi-tech solutions, with a halo of unreliability wrapping them

Mistral

[Gina22]

Hi, this time is an surfer the fastest.
An same size multihull cost expensiv, and very cost expensiv in the port.

Mr d'Artois: i have question? What is your preferred sail-config? One 1/1 140% rollfock end
rolllmain in the mast?
I prefer 14-/15/16 105% rollfock, mail with lasyjak, 2-3 reef, genakker, rectractable genakker boum, code-0

Gina22

[Doug Lord]

"Halo of unreliability" surrounding canting keels is absolutely ridiculous-and you SHOULD know better Mistral!!!!
The problem with "cruising" multihulls is the propensity of those that buy them to abuse them by filling up all that space with whatever.
The canting keel cruiser won't ever have the room of a multi but I wouldn't be surprised to see a canter like the new Stimson(Stinson?) whup some of the more houseboaty cats: it is designed to have the room of a well equipped 50 foot monohull cruiser in a 60' hull and I personally would rather go to sea in the canter.
Just so the record is clear and so my multihullness isn't questioned-for coastal racing and inshore daysailing racing I'd prefer the multihull unless of course I could sail a foiler.

[mistral]

"Halo of unreliability" surrounding canting keels is absolutely ridiculous-and you SHOULD know better Mistral!!!!

i didn't say "they're unreliable" of course i'm not so fool, but we have to admit that, if things keep going like last Sidney-Hobart, "canting keels break" may become a common speech hard to eliminate in pontoon rumors, such as "multihulls capsize in gale and are not seaworthy" or "racing trimarans split up very often" or "longkeeler are always seawothy" and so on; these are of course nonsense rumors, but anyway they exists and we have to deal with them; if you take a look at my previous comment in this same thread, you'll read that i think that canting keels may have a bright future as cruising boat technology!!!

fair wind
Mistral

[Doug Lord]

But you must at least admit: for one who says that canting keels have a bright future in cruising boats that saying something like they are shrouded in a halo of unreliability is not only not true,and unfair but fosters the kind of nonsense you mentioned in the last post,right?

[D'ARTOIS]

Look Gina, I am a solo sailor, since '82 I sail most of the times alone, so I have to live with that. Large foresails are difficult to handle and therefore I like the Cutter rig the most although it comes second to the masthead rig in upwind performance. I don't like rollreefs. I prefer to change the sail, if I have to.

I believe that we are coming on a point that we still have our pro's and contra's.
Dusseldorf boatshow started today and I will go on Wednesday to have a chat with some of our suppliers and I will hear how the production boat mfrs think about this topic. Their answers -if any- will be put in this thread when I am back.

Mistral's reply that the cruising crowd might be annoyed by the fact that the difference between a cruiser and a racer is steadily growing, regarding to speed is something that might oblige the serial boatbuilder to offer the canting keels as an option to the standard packet.
To keep it affordable, he might overlook the safety factor and opt for a cheap design. I know at least one overhere that would do so.

In Dusseldorf, I will check also if there are already commercial canting keels available for cruising boats.

[Richard Petersen]

I web searched "canting keels" on the web and found a race rules forum section called "rumors and lies" about the wide spread use of them now in everything that sails. Seems they do not know how to handle the problem.

[Richard Petersen]

The site is www.sailinganarchy.com----------- Tough talk.

[Doug Lord]

Richard did you save a link to "rumors and lies"? I think that is a section on the Sailing Anarchy website.
I'm really curious "who" doesn't know how to handle "them".....
==============================
Richard, I just went to the Rumors and Lies section of Sailing Anarchy and I didn't find a single negative comment about canting keels or any comment that could lead one to conclude:"Seems like they don't know how to handle them". Can you refer to what you read exactly or more clearly explain what you meant to help me understand?
You can find a wide variety of comment on the SA forums some enlightened and some not so enlightened.The site is lively(understatement) and many times has news before anyplace else does....

[Richard Petersen]

I will go and find the section. Be back.

[Richard Petersen]

Thereare 2 different sites of it. Do a web search of " canting keels " use the first anarchy site. Tough talk. Let me know if you find it.-----------------------------------------------------------------------------------------------------------------------------I can send a scaned email to you.

[SeaDrive]

a bright future in cruising boats

There is always the question of draft. I don't see the canter as ideal for shallow water areas.

[Doug Lord]

Sea Drive, I don't see any reason why a canting low aspect fin keel using fixed or retractable wings for extra lateral resistance couldn't be used to achieve shallow draft with some of the advantages of a deeper canting keel.Additionally, extra lateral resistance sufficient for this application could also be achieved by a canting keel/centerboard configuration...The use of wings or a keel/centerboard configuration with low aspect fin keel not only allows a shallow draft effective canting keel but allows the elimination of the requirement of any kind of trunk in the living area of the cruising boat.
Some of the advantages common to both types would be a better ride upwind with less pitching when the keel is at max cant, less ballast, and /or more righting moment.
Some canting keel builder/ designers are addressing the draft problem by having a canting RETRACTABLE keel though in the examples I've seen the keel can't be retracted AND canted at the same time. This type generally features a retractable daggerboard but could easily incorporate a centerboard if the board was placed BEHIND the canting keel. But, again, wings or a keel/centerboard combo is probably best.

[Gina22]

Hi D'Artois
25 yers ago 2 years long have I sailed the oldest hungarian Sailing ship http://www.sailing.hu/files/20892r.jpg,
that was an cutter. But an CODE 0 to 3 Beafort and normal jib over is more simple. The question have Maening do you will fast sailing or not. An ship with canting keel is slighter as with fixed keel. I can say an ship longer, but with same displacement, and with Deck Salon may be an solution in the Charter Business.

Regards Gina22

[D'ARTOIS]

Hey Gina,

Where do you sail? On the Balaton?

[CT 249]

One query about canters; how much extra do they cost (all else being as close to equal as possible) and how much extra room, comfort, performance would you add by putting that sum into a bigger boat rather than a canting keel?

We all know, the fastest boat for the LOA or rating or LWL, is very different from the fastest boat for the dollar. When the International 14s adopted T foil rudders, some pointed out that the same speed and handling gains (at least) could be obtained more easily just by adding a foot to the stern.

Then again, I suppose the modern "marina shaped boat", with its squashed overall length and overblown beam and freeboard, is all about packing the maximum space and some sort of pace into a short LOA to keep marina fees down. In that case (and in others) canters have an attraction.

I still wonder about learners ending up with canters in 10-20 years time. It will surely be a problem, just as it is when less experienced sailors end up with old racers where the rig depends on running backstays. Sure, there's no problem if you don't make a mistake, but the potential for a stuff-up makes the boats problematic in the wrong hands.

[Gina22]

Yes D'Artois, on Lake Balaton and some times on Adria.
The old ship is today 109 years old.

Regards Gina22

[yago]

The bad news is that yet another keel fell off this morning in the vendee globe.
The good news is that Nick Moloney managed to keep the boat upright by topping up his 5 tons of water ballast. ;-)

[Doug Lord]

Thank God Nick Moloney is ok ! And that the boat is still upright.
I can only assume that Yago posted this under "Canting Keel Production Yachts" because he could not quickly find another topic; it is illustrative of canting keel hysteria that started with Skandia mishap. Yago: if you're trying to break news and or contribute to the discussion it would seem that instead of a hysterical news report you would take the time to explain the FACTS!!!
Which are: Skandia experienced a failure of her keel fin; it broke 30cm below the bottom of the boat. The CANTING KEEL MECHANICS WERE NOT INVOLVED!!!!!
According to a report from Moloney on Skandia , he feels that the fin may have been damaged last week when he hit a solid object at 15 knots...
He's making for the coast of Brazil...

[yago]

Doug, right after posting I realized that my post might be misunderstood... thanks for pointing this out.

Actually I am not at all opposed to canting keels, (with or without daggerboards, check my site) or waterballast etc - I just wanted to pass the great news that, contrary to some other lost keels in the past, this boat actually is still right-way-up, Nick is safe and sort of under control. I guess that is a first and in itself a "sensation". Lets hope they get him out soon.

[Richard Petersen]

I did not take YAGOS clip to be hysterical. I do take your response as hysterical. Life will go on before and after canting keels, rudders, masts and captains.

[D'ARTOIS]

Gentlemen, remember, this is about
production yachts !!

But I am glad that it broke below the hinge system.

[Doug Lord]

Yago, I jumped on you a little too hard; my apologies for my excesses. Thanks for your follow up post..
Thanks Richard for a sober analysis...

[Richard Petersen]

D'ARTOIS, thanks for throwing our anchors out.

[Richard Petersen]

I hate to admit it, but talking about racing boats is more interesting then the latest cocktail sailboat screw ups :)

[Gina22]

Hi D'ARTOIS
"In Dusseldorf, I will check also if there are already commercial canting keels available for cruising boats."

Have you any news from Dusseldorf?

Gina22

[mistral]

here we are, two production boats suited for canting keel, they're new designs, they are both still on the drawing board.

http://www.ceccarelliyachtdesign.com/ita/CYD4003.html
http://www.ceccarelliyachtdesign.com/ita/ceccarelli80.html


fair wind
Mistral

[D'ARTOIS]

Correct, I owe you one.

Frankly speaking: I talked to people from Cariboni who countered my question with another one: which boat do you have in mind. In other words they were not (yet) approached by builders of yachtseries. As they say. Somebody from Beneteau told me that they plan - or, to say it more carefully, they may be able to offer in certain types of yachts, if the client requires, on his own responsibility, a CBF or CBTF system.
The Beneteau organisation is a very large one, with many boatbrands, and it is fully acceptable that if a client in an isolated case wants such a device added to his/hers purchase, and will pay the bill for this considerable addition, then WHO will say NO?
But this was not the intention for my thread. Even the concept-yacht Mistral refers to does not fall in this category, because it's only an idea, a proposal that may never see the glory of daylight.
From a number of designers and builders I got a very negative response. But NOT from the racing guys. Logic no?
If a company like Dehler - who produces a standard design spread over a range of boaltlengths, put a canting keel as an option on their saleslist - then I would say, ok here is a manufacturer who is able to support this idea in a sense that they might be able to produce a boat where the CK is an already integrated advancement and they are also able to support or back up any claim deriving from this modern addition.

If such a company makes that step, you may rest assured that they did not do it in one night.

The present situation is: if you buy a production yacht and you want to have the addition of a canting keel, whether or not with a foil system, you do that operation on own risk - i.e. the manufacturer or yard will not accept any claim deriving from the change of standard design. Unless otherwise agreed.
But that's lawyer's talk.

Another thing is that you buy a design that has the CK integrated in the design-profile. If in such a case a yard accepts the commission, it is automatically responsible for all the aspects of the CK concerning proper functioning etc. too. Of course only in case they do not exclude any resposibility to that design's aspect.

A few said: Ok we will accept resposibility only under cruising circumstances - not under racing- or competition conditions.

And now we are back to the statement of one of the posters, who said that the distinction between the racing yacht and the cruising yacht would only become bigger. As is more or less the situation in car racing.

It was this fact I wanted to have established and it looks that the issue of the canting keel, in whatever execution, will be applied to the yachts in the high end of the market, in that respect the canting keel will be used - as an option - to attract a group of clients that have a preference for such design-extensions.

Long time ago, we were organising seminars and classes for amateur shipbuilders. Very closely we studied specific designs and we tried to bring it to the participant's atention: where will you sail?
With that in mind and afterwards looking at the nasty waters we are blessed with, I believe that only the few racing yachts that we have over here will (finally) be equipped with the CK. Otherwise they cannot compete internationally. Unless a general accepted rule comes that directs otherwise.

In spite of all this, I do not believe that all these top-of-the-bill gadgets, can add anything substantial to my pleasure of sailing. On the contrary, I would say. I prefer the rugged type of extremely seaworthy yachts, even racing yachts. Where additions were made to improve the ship, not making it more subject to failures that can even be fatal soemtimes - if unlicky.

In my next post I will give a few examples.

In the big assembly of climates and counrties and waters of the USA you may find alway something of your liking. We in Holland have very little to choose from. We have a large but very shallow inland lake, the IJsselmeer, with lots of traffic and we have the Northsea, dangerous by nature, and spoiled by international shipping that comes from all directions. A 125 nm trip to the UK needs already full attention of the crew 24/24 - that means continuous watch all day, all night. Unexpected windshifts, lots of traffic will make you ready for sudden changes of set courses.
Do you think that I like to be pestered under such conditions with a keel that I have to haul from port to starboard or vice versa?
Come here, sail a day with me and tell me afterwards.

Please comment.

[mistral]

Artois i perfectly agree with you; Beneteau , Delher and other big mass production shipyards are not dealing with CK issue; that is the main fact , and that means that canting keel is not seen as an appealing solution in order to sell boats, that's all!!
i don't think it's a matter of reliability, simply CK is not cost/effective now, it will add something not required by market at a high price spent to develope reliable solutions; shipyards are really sensible to reliability of their product; they don't like to spend their money in lawyer to defend themselves!!! As amatter of fact we can see that their boats are quite conservative; it took a decade to bring carbon masts form pure racer to some kind of high-level racer/cruiser as it happens today, and i think that calculate reliable scantlings properly for a carbonmast is easier than doing it for a CK.

fair wind
Mistral

[Doug Lord]

I think it wold be an unfortnate step down the wrong path if companies like Beneteau start offering canting keels for boats not designed specifically for them...

[D'ARTOIS]

Exactly Mr Lord. Bingo! That is what I have said: you have to design your hull and scantlings around the CK(TF) concept - as done by the Italian designer. Because it is not an addition to - but an integral part - of the design. I agree fully. And I think that the reply of Mistral covers fully the principles of the (mass) production yards who cannot afford to imply the CK keel in their production boats but will make their high-end and therefore almost one-off designs available to this modern system. Maybe in a few years the canting keel wil become just as popular as the epoxy matrixed boat now.
In Holland, we were among the first to use epoxy as matrix material in the larger designs, and what kind of verbal abuse we had to endure when we started to promote our new application. Worse than the CF now, Mr Lord.
How we clinched with Beneteau when they started tio "energise" their hulls by using the 1st generation of untreated Kevlar in their production hulls, not expecting that by using ortho resins the laminate was subject to delamination at high impact loads!
But - in that respect we may learn from each other. What do we in Holland know about yachtproduction in the US? I learn from the fact that I see the yacht only in the environment of the Northsea and tempt to forget that there are more pleasant conditions too.

[SuperPiper]

I think that this goes against the spirit of the thread, but there are "production racing yachts" with the canting keel technology. The mini transat. Definitely NOT a cocktail cruiser. I lifted the following paragraph from the "Unofficial MiniTransAt Site": http://www.xs4all.nl/~blvrd/

There are currently a few designs in the production class active, the new Pogo2 (2003), Naus (2003), Pogo (1995), the SuperCalin (2001) and the Coco. The Coco being an outdated 1984 design , but still sailed, but more in the pre MiniTransat races... More boats want to become a Production Class, but as far as I know they are not yet qualified.
SEE BOTTOM OF THE PAGE FOR A COMPARISON IN DIMENSIONS BETWEEN THE DIFFERENT BOATS

The list of wannabees:
(2004, April)
- Mistral, no 8 is being build, did the MT 03 as proto.
- Tizef, one in the water I believe.
- Zero, 7 build, 9 ordered, first racing.
- Ginto, 7 build/12 ordered, first racing.
- Dingo, Rolland design, 4 ordered.

[Richard Petersen]

I veiw canting keels in the same light as turbines in boats. Both are proven additions for what they provide. BUT how many people really want the operational maint. of them?

[SuperPiper]

And if canting keels are not enough bother, this little fellow has a canting/sliding keel.

[Doug Lord]

I know D'artois PRODUCTION canting keels,not race boats. But I just had to say something: that is one of the most brilliant(patented) canting keel installations I know of and has had trial by ocean mile in the mini Transat. Simon Rogers designed that system-or someone copied his race winning design. It allows the keel to move fore and aft which on a boat as small as a mini is a great idea.

[D'ARTOIS]

I tell you what Mr Lord, what about designing a mini transat and enter the next TA? I checked the rules today and 6.50 is pretty controllable to build. I am not joking.
When we get back to the last picture, was the canting operation mechanical or under hydraulic power, i.e. with a manual operated pump? Then the aft- and f'orwards mechanism? Hydraulic ram?

Any idea?

[Doug Lord]

Mr. D'artois: the Rogers design is 100% manual with lines led to the cockpit to move the keel either direction....
Since we're on the subject anyway do you see that big ugly daggerboard up forward? Well I've come up with a solution that gets rid of that thing but isn't proven yet. And that is the kFOIL™ that is basically a pivoting wing or two pivoting wings that retract into the bulb. So you have extra lateral resistance when you need it upwind but it can be retracted when not needed-just one more line to the cockpit but saves room inside, retracts when it hits an object and doesn't change the balance of the boat when the keel cants.Not only that but it's easier to operate than a daggerboard. Some canting keel boats with the daggerboard so far separated from the keel fin can have balance problems(excessive weather helm) when the keel is canted because the CLR moves forward-not with the kFOIL.
I mention this because the kFOIL™ MAY be incorporated in a mini design for 2007-waiting to hear if the skipper gets his financing....

[CT 249]

I had a look over a 12m offshore racer by Robert Hick (Australian designer) the other week. I was shocked by how much in the interior space, and in the most valuable area for accomodation, was taken up by the canting mechanism. The keel box was used as a wide table, but it was not a great shape as it had no space for the legs and therefore wasn't too comfortable. The rams had to be stepped over with floor space already short because of he keelbox/table, and the extra batteries etc also took up valuable space. The crew were keen, but the cabin roof had to be very high to allow for the "plumbing" under the floor and still maintain headroom.

So while it was interesting, it looked like a rather expensive, labour-intensive, space-robbing option. One wondered how much performance it would give compared to using the same amount of cash to make the boat longer, how much more pleasant it made sailing (when you had a high coachroof to get over and/or less space down below and in my experience such things do count in short races and long ones albiet not in the 100 mile stuff). Given the impoirtance that the mass market places on cost and interior space, I could see why it may not become popular for some time.

[asathor]

There really is no reason to worry about size and cost with any new technology. What is important is that the builder don't just copy each other and keep inventing. It is pretty well know that as more builders and engineers get involved mechanisms such as those needed for canting keels will shrink and go down in cost until the cost and benefits are balanced at a point where there is a satisfactory value to the buyer.

Hydraulics for example, makes little sence on smaller boats since you loose power for each conversion you go through, whereas it seems that when you need a canting keel you will automatically have access to plenty of wind power.

Some smart people should be able to figure that one out pretty soon.

[D'ARTOIS]

Lorsail, I saw the mechanism - a very heavy 3 or 4 disc pulleysystem, I saw only part of the system - furthermore rule deny the use of any hydraulics.
Unfortunately only old sites of last year and 2003 on the net.
Unfortunately Titanium is ruled out. I can get that material quite easy and actually I am experimenting now with bonding Titanium and Carbon together w/o heatcuring.

[asathor]

Yes, a carbon rack & pinion with titanium reinforcement sounds pretty good to me!

[asathor]

Aren't you Dutchmen supposed to be sleeping?

[SuperPiper]

Asathor:

You are right! The more renditions of this technology, the sooner it will evolve into a prefered mechanism. Hydraulic rams and a moment arm consume space inside the hull. So, why not a hydraulic rotary-actuator at the pivot point? Or a geared hydraulic motor that inherently locks the keel if the hydraulics fail? I like the rack and pinion suggestion. What do you think about a lead-screw?

The Netherlands is home to the busiest port in the world. Those guys never sleep.

[asathor]

I was thinking of a somewhat loose gear (but for example wrapped in carbonfiber reinforced cage so it would be dimensionally stable) to keep friction and wear down - lead would absorb shocks but distort easily. But there would have to be slack in the mechanism somewhere of couse in case og grounding etc.

[asathor]

That reminds me of a question you probably know the answer to:

How much draft and width is considered practical if we wanted to sail down through Europe to the mediterranian on the canals? (I am sure sizes varies).

I am starting to think about retirement and have been talking up the idea of a boat in Europe with my wife. I was born and raised in Denmark and she is almost 100% Norwegian from North Dakota here in the states.

I would need a boat that could handle the Atlantic as well if that is even possible - there are some full keel and shaol draft keel boat in the 32 range that may be big enough to live on if I don't get my Canting/Retracttable boat by then.

[Skippy]

... on smaller boats since you loose power for each conversion you go through, whereas it seems that when you need a canting keel you will automatically have access to plenty of wind power.How about a manual system with plenty of purchase? For somewhere in the 20-30 ft range. At least in the low 20s. And it's cheaper & simpler.

[mattotoole]

So while it was interesting, it looked like a rather expensive, labour-intensive, space-robbing option. One wondered how much performance it would give compared to using the same amount of cash to make the boat longer, how much more pleasant it made sailing (when you had a high coachroof to get over and/or less space down below and in my experience such things do count in short races and long ones albiet not in the 100 mile stuff). Given the impoirtance that the mass market places on cost and interior space, I could see why it may not become popular for some time.

This is what gets me -- the whole value proposition. For the same money, most people would rather have a bigger boat, with more room, more comfort, easier motion, and more speed under sail *and* power.

For sheer speed you still can't beat a multihull (assuming you have a place to park it). Multihulls are expensive too, but cheap in terms of speed for the dollar. I wonder how a Schock 40 compares to a Farrier tri, in sailing performance, comfort/accomodations, and cost. Just for fun we'll leave out simplicity/elegance.

[CT 249]

Yeah, I agree it seems a bit strange to go all nuts about something that makes a mono maybe 65% of the speed of a similar-size cat rather than 63% the speed of the cat (or tri). If you want real speed, why mess about with a mono keelboat? I love mono yachts, but they just aren't super fast so why get excited about stuffing up the racing for an extra knot?

I'm not quite sure about the multi/mono speed-and-room-for-cash thing. I can't recall the numbers I've heard for the Farrier 41 (?) but I think it was pretty damn hard on the pocket, like many of the modern cruising cats.

[Doug Lord]

It all adds up! Canting keel technology has proven conclusively to be the biggest single advance in monohull speed in the last 50 years or so. Nothing can touch it for a performance monohull whether it's a cruiser like the new Stimson 60 or an all out race boat.
And you ain't seen nothin yet! Just like the hydrofoil Moth is revolutionizing speed in small boats-beating cats as well as other mono's foil equiped canting keel boats will take larger monohulls into another world of speed before too long ....

[D'ARTOIS]

You are right, I never sleep. - Of what is practical to go through the canals to France is determined by the width of the locks and the draft that allows you to sail the smaller channels.

For going North-South and vice-versa a maximimum of 3.20 mtr is designed for your waterline to top; the draft may not exeed 1.60 mtr. Sometimes you could pass with 1.80 but if there are any changes in waterlevel, you are stuck.

The width can be up to 5.00 mtrs.; practical is 3.50 - 4.00 max.

Going to the Canal Du Midi; Bordeaux - Narbonne: your draft should not exeed 1.40 mtr and the waterline-top not more than 2.40 mtr; width max 4.00 mtrs;

Going from Holland to the Med through the French waterways you may encounter as much as 200 locks all together. Maybe more. Your daily proceed will be about 100 kms.

About Cat's and Tri's - I love them both but forget about them if you want to cruise inland waters - specifically France.

If inland use is not the topic, I think I would go for the Cat. More comfortable and spacious accomodation for living on board are possible.

Read James Baldwin's experiences in the "Cruising Sailor" forum.

[mattotoole]

I'm not quite sure about the multi/mono speed-and-room-for-cash thing. I can't recall the numbers I've heard for the Farrier 41 (?) but I think it was pretty damn hard on the pocket, like many of the modern cruising cats.

That's not quite the comparison I was thinking of. The F-41 is a full-on cruising cat, not really comparable with any canting keel mono. And yes, I'm sure it takes a heavy bite out of a half million bucks.

So I'm thinking more about the 31-33' Farrier tris, costing around $225k new, vs. a Schock 40 ($???). These boats are probably similar in terms of hull volume usable for accomodation, so it would be interesting to compare the other factors.

[yago]

Of what is practical to go through the canals to France is determined by the width of the locks and the draft that allows you to sail the smaller channels.
many years ago I tried to take a smaller boat from the UK to the Med, and then had to wait it out for some months in La Rochelle, the Canal was low and my draft was higher than given on the papers... then the winter came, then I started building another boat, then another... It took me 15 years to leave the area again. Very sticky environment ;)

[Gina22]

Hi, not my Information, Mighetto has wrote, in another Canting Keel Topic 180 K$

Gina22 :)

[Richard Petersen]

I am a good arm chair designer. Why not make the keel fully controllable? Canting, left-right... slide, fore- aft...pivot , port- starboard... depth, up-down-retract. All from the helm JOYSTICK. This would allow a REAL performance advantage in all wind directions and course directions. WELL? :) :)

[sorenfdk]

Hi, not my Information, Mighetto has wrote, in another Canting Keel Topic 180 K$

Gina22 :)
Please don't believe anything Mighetto says! This man is bordering on the insane. If you don't believe me, check out the "TP52" thread or the "Incredible "Secrets of Yacht Design" website..." thread.

[asathor]

Let me know how many canting keels you would like for $180k each. At that price I will even make them see through and water ballasted with aeration for the creatures that move inside.

On a more serious note, I looked at some of the Italian links, they are talking HUGE boats. 20' to 40' boat keel "canters" ought to be possible for less than the cost of a matching engine size in standardized production parts (not counting the keel and existing building costs).

Richard, I will invent you one with all the features you asked for, in fact I will even spec you a stearing yoke with fingertip switches to replace the wireless wheel/rudder, but you will have to conceptualize your own horizontal wingsail mechanism inteface ;)

[D'ARTOIS]

I believe that - with reference to the canting keel - we know where we stand at present and that this thread may be closed for the time being. Unless a certain Mr Mighetto buys his Schock 40 - we might then reopen it.
:confused:

[Richard Petersen]

Asathor, I will operate the concession stand,$$. :p

[brian eiland]

Another Canting Keel (retractable yet)

courtesy of www.sailingscuttlebutt.com

LAUNCHING
We normally don't report on boat launchings, but there is a pretty
significant one happening on Monday, February 14 in Auckland, NZ. The boat
is the 100-foot Maximus, which is modestly described as the 'World's
fastest and most advanced supermaxi.' Designed by Greg Elliott and Clay
Oliver for New Zealand businessmen Charles Brown and Bill Buckle, boat's
featured include:
- Light displacement carbon fiber construction
- Rotating wing mast
- Retractable canting keel
- Maximum power to weight ratio
- 500 Square Meter upwind sail area
- 800 Square Meter downwind sail area

Previous commitments will prevent the curmudgeon from attending the
launching, but there is lots more information and photos on the GBS
Yachting website: www.supermaxi.co.nz/

[brian eiland]

Chris Ericksen:
As one who was in the hydraulics business for 15 years, the stories ofcanting-keel problems occurring when an hydraulic ram or cylinder is fully extended leads me to wonder why people don't use a different hydraulic device to cant a keel: a rotary actuator. The kind I am thinking of is a rack-and-pinion device wherein pistons attached to either end of a rack rotates a pinion gear that would in turn be attached to the axle of the keel. I am sure folks smarter than I have considered and rejected this, but I wonder why this simple and robust device has not been used heretofore.

From Kenny Robertson:
As an additional comment to Chris Ericksen's comments about using a rack and pinion, has anyone thought of using a worm gear type of actuator [like the tuning nuts on a guitar]. The advantage of this is that it is a one way system, where the actuator can move the keel, but once in position, it would be impossible [if we exclude catastrophic mechanical failure of components] for the keel to move even if the actuator was removed completely. It would also be very easy to add a manual emergency system to it. Once again to echo Chris' comments "I am sure folks smarter than I have considered and rejected this, but I wonder why this simple and robust device has not been used heretofore."


From R. Geoffrey Newbury (Re: Canting Keels):
I've been reading Conrad Humphrey's posts on his site. I am utterly astounded that anyone would build a canting keel system and expect to race it around the world without any arrangement which would allow the keel to be physically pinned in position. These designs rely totally on the integrity of the hydraulic system. Have these designers never heard of Murphy's Laws? Is there any reason why the keel design could not allow for the keel to be pinned with a hulking great clevis pin? For safety reasons ORC should ban canting keels which cannot be physically pinned in at least the upright position. Anything less than that is manifestly unsafe

[Doug Lord]

Someone on another forum pointed out that the new Offshore Regulations in the ISAF/US Sailing rulebook have just such a requirement. Don't have my new book yet so I can't verify that.
But I sure agree with it...

[Richard Petersen]

I know this is not going to sound like me, Mister Cautious, BUT. Hydraulic self locking systems are-should- be safer than any other, due to very simple and accurate relief valves and end of travel cushioning stops. New applications in a skimpy safety margin specification, RACING, make any improvement liable to look bad.-----------------We do not put locking pins in skyscraper super fast elevators. Why a slow canting keel. If you do not know what you are doing, blame someone else, and make it offical. DUH DUH. :eek:

[bobothehobo]

Don't know if you guys have heard, but the sister boat to Skandia in the Vendee Globe, Ecover--skippered by Mike Golding, has just lost her keel (canting) only 50 miles from the finish....Mike is currently making 3 kts but has to sail upwind to the finish and does not have the ability to tack....he has sailed 23000 miles and is currently in 3rd place...lets hope he can someone finish safely....

www.vendeeglobe.org/uk

[amolitor]

Yep, I have been following the Vendee Globe, and am trying to figure out who did NOT have keel problems. I make it 4 boats that have non-fixed keels that have not experienced trouble yet (that we know about). Two of the canters seem to have simply broken off, which might well have nothing to do with canting per-se. I can count at least three other non-fixed keels that have had trouble.

However, this is a very tough race, and you expect a lot of stuff to break! Arguably a design that breaks 50 miles from the end is plenty strong enough for, well, any other application you can imagine.

[bobothehobo]

I suspect Mike began to have problems with the Canter quit some time ago, the flaw just became fatal at this point....

[bobothehobo]

PRB (Vincent Riou) who finished #1 had problems with his keel all the way up the Atlantic but didn't reveal it until after he finished....strategy and all...

[mistral]

so let's sum up about canter and Vendee globe:
-Sill e Voila/ Jourdain: failure with a crack in the keel support, retired
-PRB/Riou: hydraulic failure of a ram, kept on racing
-Skandia/Moloney: total loss of the keel, retired
-Norbert Sedlacek/Brother: failure of the keel support, retired
-Ecover/golding: partial loss of the keel, hope he'll get the finish line!!!
-Hellomoto/Conrad Humpreys: failure on starboard ram, keep on with port ram

have i forgot someone ????
quite impressive, isn't it???
The thing that keeps me astonished is that keel failures are probably the only kind of failure that Vendee's guys/girls are unable to repair; they've repaired almost everything on their boats, but with a keel total failure you just have to go home, if you can, or at least try to drive your boat in spite of the problems, like Vincent Riou has done with PRB.
I think canting keel issues are the real problem to deal with for IMOCA designer now!!!

[Doug Lord]

Funny(no so funny) but in every one of those cases it was a COMPONENT that failed-nothing whatsoever endemic to canting keel technology.
Work will have to be done to find out why keels are breaking off under the boat; why bearings have failed and why hydraulic rams have failed. Similar designs have failed-not sure what that means for sure at this point but the designers are going to have to look closely at the specific problems.
Lumping all these individual component failures into one batch and saying canting technology is bad is ridiculous.

[bobothehobo]

Go Mike Go! I would hate to see him not make it 50 miles from finish....ughhh, 23,000 miles down, 50 to go....

[bobothehobo]

I for one am not saying canting keel technology is bad. I actually believe it is here to stay, I guess everyone just needs to sharpen their pencils, whip out the calculators and figure this thing out.

I think like everywhere else on these extreme boats, everyone is trying to save every extra kilogram possible so the limits are always pushed.

[Doug Lord]

Bobetc., I think you're right. There will be some serious engineering analysis of keel fins ,rams and bearings...

[amolitor]

I agree also. The Globe is about the toughest race out there for a keel technnology, and in a sense it's good to have these failures for analysis.

A couple of remarks:

No boats or lives have been lost in this race, the water ballasting systems seem able to compensate even for keel loss. The more common failure modes of the canting systems require some jury-rigging to hold the keel in place, but leave the boat sailable -- even competitive!

Certainly these have been component failures, but the systems are made of components after all. The keel losses may have many root causes, but it is at least possible that the lighter keels used in canters, combined with the additional stress on that fin, increase the loss rates, for example.

Having a bunch of hydraulics also just plain adds parts that can break.

All that said, I certainly agree that canting keels are good technology and here to stay. The architects know how to build this stuff to be damn near bulletproof, and I dare say that after this race they'll be even better.

I like Lee Helm's moveable water ballast as well, though ;)

[Richard Petersen]

Did somebody say the boats have gone 23,000 miles? Even 2,300 miles of racing? You sail boaters who are pissing and moaning about failures, are crybaby idiots, who want your toy to be abused and last foreever!!! Get off of your DRUGS!!!!!! I really can not believe you call yourselves PROS!!!!!!!!!

[amolitor]

What? I have no idea what you're trying to say, Richard.

[mistral]

Bobetc., I think you're right. There will be some serious engineering analysis of keel fins ,rams and bearings...

it's a like a pendulum swinging; this time they made (generally speaking) keels lighter, maybe too much lighter, i think they'll learn the lesson quickly; the next time probably keels won't be an issue and the critical area will be different; these boat are always on the edge!!
it's difficult to compute exactly the amount of stresses that a keel will suffer in a vendee globe; this time they've clearly underestimate them, this will cause new tests and new simulations to improve the reliability of the system, and more knowledge wich may lead (in the next years) to a reliable use of canters in a greater number of boats.

mistral

[Richard Petersen]

Abuse the boats, and when a newly incorporated part, which is massive, fails, start whinning about designers abilities. BULL ---- You guys could break a solid TITANIUM keel and be complaning!

[mistral]

Did somebody say the boats have gone 23,000 miles? Even 2,300 miles of racing? You sail boaters who are pissing and moaning about failures, are crybaby idiots, who want your toy to be abused and last foreever!!! Get off of your DRUGS!!!!!! I really can not believe you call yourselves PROS!!!!!!!!!

these boats are built to do that, MUST be built to do that!!! if i were a racer, i would like that my boat lasts at least 'til the end of the race, not forever, let's say just 500 miles more than the end of the race!!!! So what the hell are you talking about????

best regards
Mistral

[amolitor]

Canting keels are not new. The winning boat, PRB, also won the last edition. The keel was modified, made finer and lighter for this edition. Not sure about the hydraulics.

Anyways, I don't think anyone is whining about the designers abilities, I think we're just pointing out that for this edition the canting keels seem to be the weakest link, and the place the architects will be focusing on for a while.

No need to get angry and throw around all those exclamation points, I'm pretty sure we're all on the same side here.

---

P.S. I certainly never called myself a pro, and I am not.

[Richard Petersen]

Richard, are you being as hard on the RACERS as they are on the DESIGNERS? YES_ they are supposed to work together to TRY and beat Mother Nature, not each other.

[Richard Petersen]

Mistral, does anybody in this racing have the time and money to run 50 to 100 Globe races, to test parts before using them in competion?? :p

[mistral]

of course he exists!!!! Larry Ellison, but unfortunately he's not interested in Vendee globe or ocean racing :) :) :) :) :)
i'm just jocking ;)
anyway, i'm convinced that IMOCA are boats in wich skipper and designers work in tight contact to satisfy each other's needs, so i'm not pointing my finger on designer, it will be stupid; i've just said that in this editions keels issues have been the critical area, most of all because there are really few things that a skipper can do to solve a keel failure. May be the next time rig problems will be the major problem to deal with. :confused: :confused:

Mistral

[Richard Petersen]

Ocean racing in stormy conditions is a lot like competing in professional Bull Riding. The competition has never been between one another. The real competitors to beat, are the WEATHER and the BULL. :p

[Richard Petersen]

Did any of the boats have strain sensors continously monitoring different points so we can tell how much more beef needs to be built in, where it is needed? It could SATAL. trans. without bothering the crew.-----------------------------Or scare the cra- out of them, if they saw the overloads they were putting on the boat.

[bobothehobo]

On his race and finishing Mike Golding said this morning:
"Vincent and Jean (first and second) just sailed so well. Even when we turned in Biscay there was only 50 miles to the lead and there was still a possibility of winning. We all know that sailing can be a very cruel game and things can change and Biscay presented one last opportunity and we were all pushing, pushing, pushing to see what we could break the hold that Vincent had but it was too strong. Yesterday I was going to come in to Les Sables d´Olonne disappointed with not being the winner, but happy with my race. I can´t complain abut my race. I´ve had a perfect race. I have a great boat, a great sponsor and a great team."
Having finished third, at one stage making up a deficit of 811 miles to lead the race for two rankings, Golding said “Everything about this race is excactly what I came back to it for. That is until the keel came off yesterday afternoon, which is a weird thing to say, and now I just feel lucky to finish. Lucky to be third and lucky to still have my boat. The boat has taken care of me. I’m just happy to be here.
Vincent and Jean (first and second) just sailed so well.

[amolitor]

This is getting a little off track, but I'm going to be a fanboy for a moment. All three sailed tremendous races.

Vincent showed himself a superstar meteorologist and strategist. He simply knew more about what was going to happen than anyone else, and used it correctly. Whenever he was doing something odd, it turned out to be the right solution.

Jean probably sailed better and harder, and kept up the slugfest with Vincent for the entire race, despite not always guessing right on the weather. I think Jean was out-thought by Vincent, but stayed in the race by out-sailing him.

And Mike, of course, a staggering record, simply sailed his brains out, made up a 4 day deficit, and then in the dramatic conclusion somehow managed to keep the wet side down for 50 miles without a keel! That's some seamanship. Nick did roughly the same stunt earlier, but he used his engine, if I recall correctly. It was impressive as hell both times ;)

All three smashed the previous monohull record to pieces. Any one of their three times would have been enough to make them the fastest monohull, and the second fastest solo sailor in any type of hull.

[asathor]

Keels always fall of if you don't attach them right. So do doors, the canoe on your cartop and the occational sailor who forgets why he quit drinking.]

I once killed a Hard Drive rated at 15G by dropping it 12 inches. Whoever invented that rating must not have known of the concept "intended purpose" (freefall at 15G is not really common in computers).

When a keel falls of, it it usually because one or more component, overstressed for an extended period of time, break. Getting the calculations right is an engineering task not a design task.

Maybe some of those teams need fewer architecs and designers and more engineers???

;)

[Richard Petersen]

If the engine said " More thickness and weight in the keel area. " I do not know if he would get a bonus for a better design. :eek:

[brian eiland]

Go Mike Go! I would hate to see him not make it 50 miles from finish....ughhh, 23,000 miles down, 50 to go....

It might have been a rather dejected and slump-shouldered Mike Golding that sailed across the finish line of the Vendee Globe in the early hours of this morning, if the keel had still been attached to his Open 60 yacht Ecover. But having been forced to nurse his boat for the last 14 hours across the Bay of Biscay - with only his flooded water ballast tanks and twin daggerboards as barely adequate stabilisers for the stricken yacht - it was an elated and jubilant Golding that reached Les Sables d'Olonne Friday. He is the first person ever to have finished an ocean race without a keel. (ed note: Well not exactly, most multihulls don't have keels ;) )

He thrust his arms aloft and fired off red flares, very much as Vincent Riou had done little more than 24 hours earlier in celebration of his Vendee victory. After what Golding had been through the previous afternoon, faced with the prospect of retiring from a 24,000-mile race just 50 miles from the finish, he too was celebrating victory - victory simply in having completed the course. "Having this happen to me has made me realise just how important third place is to me," smiled Golding at his press conference today. "It's made third feel pretty good."

Golding returned to rapturous applause in the French port Friday morning. The crowd hung on his every translated word as he recounted the extraordinary events of the previous afternoon. "I was sailing in 20 to 25 knots of wind, with two reefs in the mainsail and the Solent. So the boat was well loaded, well powered up. Suddenly I felt the boat lean over from what I thought was a gust of wind. I jumped into the cockpit to release the mainsheet." When releasing the mainsheet failed to bring the boat more upright, Golding was concerned. He went through the boat, trying to find the source of the problem. "I tried to dial the keel up, I checked I didn't have water ballast in the wrong tanks. Then I went to the edge of the boat to look for the keel and couldn't see it."

This is when Golding got really concerned. He went down below to peer through the endoscope that allows him to view the keel below the hull. "I looked through the endoscope at the top of the keel, but that was inconclusive. So then I opened up the escape hatch underneath the boat,put a diving mask on and put my head under water. That was interesting, because the boat was still doing six knots at the time. I looked under the boat and there was a keel there, but it was in a strange position."

Golding was scratching his head in bewilderment, not quite able to compute what had happened. "You expect your keel to be attached to the boat. It's something that you take for granted," he said. But when he looked underneath the boat again, the keel really had gone. In retrospect, Golding believes that the first time he looked the keel "was hanging by a thread". The next time he looked, it had snapped off altogether, almost flush with the bottom of the hull.

"Suddenly the boat was three tons lighter, and I thought 'Great, here we go,' joked Golding. The reality was that the skipper was seriously worried, not only for the boat but for his own safety. "My immediate thought was retirement. I thought there was no option about carrying on." But having dropped the sails and flooded the ballast tanks with water, Golding had time to weigh up other options. He decided to hoist some a staysail and a fully-reefed main - a virtual handkerchief of cloth compared with his normal sail plan.

To get his head round this new way of sailing, Golding said: "I imagined I was on a Thames barge with daggerboards and no keel, just that instead of carrying a cargo of 10 tons of coal I was carrying a few tons of water." Gradually the 'Thames barger' gained confidence with his new set-up and even unfurled the Solent sail to generate more power. The boat picked up in speed and was averaging 7 knots, even touching 9 knots at one point. When Golding crossed the finish line at 03 hours 17 minutes GMT, the relief was palpable, the reward immense. - www.mikegolding.com

Updated Vendee Globe gallery: www.sailingscuttlebutt.com/photos/05/vendee/

[brian eiland]

Vincent Riou, winner of the Vendee Globe, spoke exclusively to Sue Pelling from yachtingworld.com about the Vendee Globe Race and his views on the current keel dilemma. Here's a brief excerpt:

Avoiding weather systems is one thing but experiencing a disaster such as losing a keel is something that's surely on the minds of most yachtsmen as they head south. The recent spate of keel loses particularly during the Vendee Globe is a big issue right now and one that undoubtedly needs dealing with before the situation gets worse. Commenting on how the issue could be dealt with and whether there should be some sort of working party set up within IMOCA to address the situation, Riou said: "Interestingly they have tried to do that before. The architects agreed but the builders didn't want to do it. Maybe now after so many problems with keels in the Vendee Globe, they will. I too think they should work together using the knowledge of everyone, allowing everyone to talk about the various experiences and come up with an agreement.

"There is actually a rule in other classes such as the VO70s where they have to agree on certain coefficients. I say why not to that but I'm conscious that it's virtually impossible to check it and it would cost a lot of money because each competitor would have to give their keel plan to the IMOCA, and the IMOCA would have to pay someone to do the calculations in structure. "I think the architects should make the most of each other's experiences and we could force them to communicate where each one has to say the situation they are in to enrich the collective so we don't do anything stupid.

In an effort to defend his title and become the first ever two-times winner of the Vendee Globe Riou is adamant he'll do the next race in four year's time. Thoughts on a new boat? Riou concluded: "Yes, if I did it again it would definitely be in a new boat."
- Sue Pelling/Yachting World, full story: http://tinyurl.com/4nuk8

[Richard Petersen]

If a builder and a architect of a race boat can't agree, why would they accept a engineer, unless he was needed to hold the door open for them. :eek:

[brian eiland]

Nigel Irens on the keel problem....

The recent spate of keel failures particularly in the Vendee Globe where three boats lost their keels including the British sailor Mike Golding whose keel dropped off just 50 miles from the finish line in Les Sables d"Olonne last week, has led to debates about how to resolve the situation and whether a designer/boatbuilder working party should be set up set the ball rolling.

Irens added his view on the current keel situation: "I think we're in the equivalent situation we were in when we were learning about over-stiff panels on hulls. Clearly something is wrong, and clearly when there's a whole batch of boats with possibly the same problem something will have to be done. Obviously they [design teams] will go back to the drawing board and try and find out what it was and make it better for next time. The thing to remember is that we as designers do as best we can but sometimes there are failures. But in a way it's an advancement of what we're doing and we learn from when something breaks, so that input is very important and they just seem to have hit a problem on the keels."

from an interview with YachtingWorld

[Doug Lord]

So what do you think, Brian?

[brian eiland]

I wouldn't strike them out of the picture because of a few failures. I think you must be bold to advance the art, and sometimes that can get you in trouble, trying new things. But to have never ventured forth...nah.

Would I go out and sail one of these vessels across the ocean, with this big moveable lead weight under me, and all kinds of hazards to hit? I don't think so. I'll stick with multihulls.

I would point out to anyone interested, Nigel's comment, 'we were learning about over-stiff panels on hulls' of the ORMA 60's per my posting at http://boatdesign.net/forums/showthread.php?p=37049#post37049

Regards,Brian

[Doug Lord]

Yeah, I think the canters will improve but as for me-at least right now give me an unballasted monofoiler or a small multifoiler any time...

[Raggi_Thor]

mmmm, not a plenty of boats, considering that backman 18 is still on the drawing board .....

Mistral

We are now starting production of the Backman 18 as a kit for amateur builders. I know, it's not really a cruising boat (basic camping facilities) and it does not have a canting keel. I just wanted to mention it anyway :-)

[Vega]

Gentlemen, remember, this is about
production yachts !!



This is a production boat. It is an all carbon boat and it is not more expensive than the typical boat of this size, on the contrary.

It is an "OFF-LIMITS SINGLEHANDED PILOTHOUSE PERFORMANCE CRUISER" with an optional canting keel.

http://www.shipman.dk/articles/?m0=6&m1=91

About price: " Pricing considerations

Mainly the budgets in production boats is appr. 1 M Eu in the low-tech level and appr. 2 M Eu in the carbon/epoxy construction (like Swan 601 or Wallyno).
None of these boats, however, fulfill the brief for a shorthanded high/performance ocean flyer.
Shipman 63 should be placed competitively at appr. 1,2 M Eu ex tax including a retractable bow-thruster, a genset, A-C, desalinator but ex sails."

http://www.shipman.dk/

I like this one, but I have to say that when I will buy one:p , I will command the lifting keel option ( I am sure that the performance is enough for me). Of course a Gentleman racer (one that likes to win races in a comfortable way) will prefer the canting one.;)

[D'ARTOIS]

Paulo, I remember that the topic went about cantin keels.

The design looks absolutely gorgious and I believe the major part of claims that hey make. Although - for practical reasons - I would not opt for a canting keel but rather - as Paulo wants also - a lifting keel. In a boat of 50 - 60 ft that can be hardly an obstacle.

The price is something different

[stewi]

I’m not easily giving up on the canting keel for a cruising boat. I do agree that the cantilever mechanic impacts the interior. However, I came up with a design proposal.
1. The canting keel is activated by a ring shaped foil.
2. The ballast keel is directly attached to the ring shaped foil.
http://img378.imageshack.us/img378/4849/canting6vq.jpg

[Vega]

Baltic 56.01,that's another cruising production boat with a canting keel:

http://www.balticyachts.fi/graphics/pdf/B56-01_interior.pdf
http://www.balticyachts.fi/Yachts/56/index.php

This is not a racing boat. Look at this interior:

http://www.balticyachts.fi/Yachts/56/index.php?gal=1&pic=8
http://www.balticyachts.fi/Yachts/56/index.php?gal=1&pic=10

[brian eiland]

I posted this article under the Volvo 70 thread before I remembered this thread on canting keels in general
_________________________________________
RAM SHAM AT BOTTOM OF THE WORLD
The failure rate of the boats in the second leg of the Volvo Ocean Race,
from Cape Town to Melbourne, has reached an unacceptable level, with two
boats so badly damaged after three days' racing that they have had to put
into South African ports while the other five hurtle across the grey
wastes of the Southern Ocean, clocking off more than 400 miles a day.

Those who are close to the designers of these boats are critical of the
relatively short time that the organisers provided between issuing the
outline rules for the boats and the starting date of the first leg in
Spain - a matter of 12 months. They say that it did not provide adequate
time for them to design and test the complex systems demanded in these
ocean greyhounds.

Their complaints appear to be confirmed.

The problem for Ericsson Racing is in a broken hydraulic ram... it is
exactly the same damage that she suffered in the South Atlantic earlier,
and on which her shore team spent three intensive weeks of repair and
reconstruction in Cape Town.

Russell Bowler, the engineering partner and president of Farr Yacht
Design, whose firm designed the naval architecture for Ericsson Racing,
indicates that the demands of the sailors is in some ways compromising the
engineering of these boats and contributes to their failures. "Hydraulic
rams," he says, "are in daily use throughout the world in earth-moving
equipment and there are very few failures there."

Sailors are not content to use the chromed steel that is the usual
material for the pistons in the hydraulic equipment and demand lighter
materials, notably titanium. "It is not simply the difference in the
metal, but the way that some of these parts are machined," says Bowler,
"it is that that leaves a lot to be desired."

Bowler suggests that the double-ram system may well be a contributory
factor in the failures and suggests that extra time for testing the boats
may have disclosed this earlier, had the time been available.
-- BobFisher in the Guardian, the full article at
http://observer.guardian.co.uk/sport/story/0,,1681811,00.html

[D'ARTOIS]

Well Brian, with a little bit more knowledge and initiative they could have avoided their problems. But the Americans and other countries are lightyears behind the Russians in metallurgy and related topics. Furthermore, there are only a few alloy/types in the market and for the rest you have to go to other levels of industry.

You can play a few tricks with surface treatment of titanium but you must know what excist and what not. If you don´t have the knowledge, you won´t find it.

And that´s the way it is......

[brian eiland]

As I look back on that recent posting of mine I think Russell Bowler may be unfairly insinuating that the titanium rams are at fault. Correct me if I'm wrong, but aren't most the failures associated with the supporting structure(s)?

I do think he might be on to something with the idea that the double rams could have something to do with the problem, particularly if these powerful hydraulics were working at odds with one another on certain peak occassions.

[guit]

A 35-footer with CK (http://www.maxfunboats.nl/news.php?pos=0&nid=48) is going to be build in the Netherlands. Not exactly a cruiser anymore, but the basic maxfun 35 is said to be build as a racer/cruiser... I've seen one with fancy leather upholstery, but a cruiser? Okay, this is what they say themselves:"Racing is an option, but not a must." From:MaxFun Boats (http://www.maxfunboats.nl/boat.php?boat=7)

[D'ARTOIS]

Quit: very interesting - but, and you will agree with me, this is not a family cruiser as it is a VERY wet boat!!!

I am almost sure that the hydraulics are supplied by Holmatro and the system by Cariboni.

I will check this and frankly, the boat looks are super good. It is a very interesting opportunity to see the VPP outputs of both boats and also see the differences in the daily practice. Paper is very patient and you may feed people with formulaes and all kinds of teste but nothing is more unveiling as a real test!

[guit]

I can't say the thought had crossed my mind that this new MF35CK would be a family-cruiser. Same goes for the standard MF35. Interior looks nice, but the "cruising" will probably be sailing the boat from one race to another.
I'm quite interested in implementing new technologies (that is part of my study, how convenient), therefore this drew my attention. It may just be a boost for the large-scale use of the canting keel. But it could also prove that the canting keel is to expensive for use other than in high-tech one-off racers.
Keep us informed!

[Doug Lord]

Too bad they're not using CBTF. A fixed daggerboard in a canting system is just slow-particularly upwind. Even a CBTF/ripoff system such as that on Maximus would be faster than a system like this.
Maybe I missed something: does the "daggerboard" pivot?

[D'ARTOIS]

I will check this, also about pivottingdaggerboard. A mail has already been send.

[RHough]

Too bad they're not using CBTF. A fixed daggerboard in a canting system is just slow-particularly upwind. Even a CBTF/ripoff system such as that on Maximus would be faster than a system like this.
Maybe I missed something: does the "daggerboard" pivot?

Can anyone explain why CBFT should be faster than a canting keel with a fixed board?

A few numbers and some theory?

[usa2]

because CBTF (or any forward moving foil) can cancel out leeway. If theres a fixed daggerboard the boat needs to steer higher much higher to achieve the same degree of leeway.

Doug i am guessing they didnt use CBTF because they didnt want to have to pay the fee.

[Doug Lord]

One of the biggest problems with canting keels is the extra lateral resistance required with a canting keel since as the keel cants it loses it's ability to counter leeway. CBTF is the best system around for canting keels because it is a SYSTEM:
1) it uses a low wetted surface,fairly narrow hull.
2) it places the twin very high aspect ratio foils at points along the hull where they contribute to a reduction in wavemaking resistance.
3) It uses a high cant angle keel-50-55°.
4) It reduces the fin to just being a strut which further reduces wetted surface(see #5)
5) Last but not least it uses collective to control the two foils at the same time in the same direction as well as a rudder to turn both foils opposite directions. By using collective the boats' leeway can be reduced to zero so that the short thick strut chord section is not developing induced drag and so the hull goes thru the water straight as opposed to at some leeway angle. The collective can be used tactically to actually make the boat go sideways for short periods.
6) Because of the twin foils the boat has excellent downwind control and greater manouverability than any other system.
============================
2, you're probably right-the fee is generally 5% of the cost of the boat . Seems like they give up an awful lot to be so falsely frugal...

[BOATMIK]

Hi Lorsail,

Apologies for dropping out on you like that - I had to go outside into the real world for a bit. So have not been posting.

I think that our discussions

About whether canting keelers were a real breakthrough or purely within a restricted frame.
About whether they could ever be as fast as multihulls.

Was quite comprehensive - I even did some rough calculations to show the Righting Moment of a canting keel is miniscule compared to the righting moments acheivable by multis.

But I feel that I am not going to convince you.

And you are not goint to convince me.

I can't think of any additional arguments IN THAT AREA.

So I won't be pursuing it further until I do!

Thanks for all your hard work!!

And I am really pleased that you actually design and build boats too - there are too many spectators in this world!

I may pursue another argument or two though - probably not as extensively.

Michael Storer
www.ozemail.com.au/~storerm

[RHough]

5) Last but not least it uses collective to control the two foils at the same time in the same direction as well as a rudder to turn both foils opposite directions. By using collective the boats' leeway can be reduced to zero so that the short thick strut chord section is not developing induced drag and so the hull goes thru the water straight as opposed to at some leeway angle. The collective can be used tactically to actually make the boat go sideways for short periods.
6) Because of the twin foils the boat has excellent downwind control and greater manouverability than any other system.


Poppycock. The total lift requirement does not change. Altering the AOA of one element to reduce it's lift to 0 (thus reducing the induced drag of that element to 0) just adds to the lift required of the other elements. The Total induced drag remains the same.

I'll buy the reduced wave drag from reduced overall displacement, and I'll buy that the hull not side-slipping through the water may reduce drag.

Of these two, CBTF vs cant with a fixed foil only the second (reduction in hull drag due to angle) is a CBTF feature.

Off the wind you only need a small part of the lift that is required when sailing upwind. With CBFT you pay a drag penalty for area you don't need when lift requirements are low. Sure you can move the foils so the aft foil is lifting more than the front foil so you get stability, but you have more area in the water than you need. A retractable foil forward with a trim tab would allow drag reduction in both cases. Maybe someone should try it?

[usa2]

People do use daggerboards with trimtabs in Australia and New Zealand. Skandia, Nicorette, and Maximus are the notable big boats. Maximus is supposedly currently involved in vaguely defined legal proceedings CBTFco over her daggerboard/trimtab arrangement, though Skandia and Nicorette have not been noticed(?) by CBTFco.
Doug is there any reason why CBTFco is ignoring them?

[RHough]

People do use daggerboards with trimtabs in Australia and New Zealand. Skandia, Nicorette, and Maximus are the notable big boats. Maximus is supposedly currently involved in vaguely defined legal proceedings CBTFco over her daggerboard/trimtab arrangement, though Skandia and Nicorette have not been noticed(?) by CBTFco.
Doug is there any reason why CBTFco is ignoring them?

Rats! and there I thought I was on to something new! ... always a day late and a dollar short ... :(

[Doug Lord]

Actually, it's not. By using the collective the (whole boat)induced drag is substantially less than it would be if collective was not used. Thats the point. The twin foils "relieve" the fin and the hull of any function in developing lateral resistance.
CBTF boats can be sailed with the twin foils at 0° angle of incidence; in that configuration the two foils , the hull and the keel strut+bulb together develop the same lateral resistance(lift) developed by the twin foils alone(at approx. +3° angle of incidence)albeit at a much higher cost in induced drag. So the lift required stays the same but the use of the twin high aspect foils to generate all the lift required w/o assistance from the hull and the fin+ bulb reduces (whole boat)induced drag.
Again, if the twin foils are set at 0° angle of incidence relative to the cl of the boat then the whole boat, foils ,fin and bulb will operate at an angle of attack(AOA) to the water flow thus generating lateral resistance-with high drag. With both foils turned to an approx. 3° angle of incidence relative to the hull cl the foils are operating at an approx. 3° angle of attack (AOA) while the hull ,fin and bulb are at 0° AOA. While lift is the same in both cases drag isn't since in the second case all the lift is being developed by twin ,high aspect foils which are much better suited to developing the lift required at lower drag(than the whole boat doing it).
==========================
The Maximus system was one of the first prototype CBTF systems tried years ago-it is not as fast as the current version. CBTF does not ignore ANY infringers......

[BOATMIK]

The conservative yacht clubs always had a number of arguements against multihulls. Some of the arguments were strong, some were weak. The two strongest ...

One was safety

Second was that it would split the fleet. The multis would always come in first, so the monos would be forgotton except in terms of handicap results and would become irrelevant to the watching public.

SAFETY
I won't argue strongly either way here - I think that over the last 45 years multis have developed sufficiently to be reasonably safe with families and others using them for sailing extended distance.

And this discussion is about the upper limits of performance where the occasional crash is newsworthy but not taken to be too serious - a bit like formula one car racing. Some risk but all participants know the risk of using a cutting edge bit of machinery at high speed.

SPLITTING THE FLEET
As canting keelers - the larger ones only possible through power assistance - become more popular they will completely outclass conventional keelers.

As we saw with the press for the Hobart Race - TV, newspapers, radio - EVERYTHING WAS ABOUT THE CANTING KEELERS - less than 10 percent mentioned the other boats.

By the time the conventional boats were starting to get to Hobart almost 24 hours later the press and presumably the public interest in the race had faded away.

Canting keelers have split the fleet the same way the monohull clubs have argued that allowing multihulls would

They make non-canting keelers obsolete in racing terms. If they become more popular the huge number of conventional boats will be ignored.

So if both of the traditional arguments of the conservative yacht clubs (who are the power behind the international bodies) have been voided - why not allow multihulls?

Multihulls are faster - the arguments for canting keel boats is made on the basis of performance - so more performance is better - Yes?

This indicates the irrationality of the excessive hyperbole about canting keel yachts.


("irrationality of the excessive hyperbole" is not a bad case of excessive hyperbole itself!)
________________________________

Canting keels (made possible in larger sizes by allowing engines to be run) don't improve monohulls in any way except performance.

1/ They don't make monohulls safer
2/ They don't make them more user friendly
3/ They don't integrate into the existing fleet
4/ They don't make them cheaper
5/ They don't improve the suitability of the boats for a variety of uses.

1/ Without getting too deeply into the safety aspect - my position is that multihulls have proven themselves to be pretty reliable for general use - even some quite quick ones.

2/ Anyone can sail most of the production multihulls that are around - including some quite quick ones

3/ Multihulls and canting keelers both fail to integrate with the current fleet

4/ Are multihulls cheaper in every way? I would argue here, since we are talking about performance - that they are cheaper because you can build a smaller, less complex boat for the same performance.

5/ Multis - are used for a huge range of activities by average people. Canting keelers (at least the ones with large canting angles) will always require crewing at the highest level of skill to deal with tacking and gybing, and may need MORE THAN A SKILLED CREW IF THE CANTING MECHANISM OR POWER ASSISTANCE, OR ELECTRICAL SYSTEM, OR THE ELECTRONICS FOR CO-ORDINATION OF RUDDER AND CANARD FAIL.
________________________________________

So a disclaimer - Everyone can sail what they like. But there is a wider duty of care for all of us to discuss whether certain changes are good for the sport/recreation of sailing.

A second disclaimer - I am a dyed in the wool monohull sailor. However, there are two times in my experienc where multis are unexcelled.
1/ Ocean racing it makes sailing fun for even for those sitting on the rail. The speed makes ocean racing more tactical because of the speed available.
2/ Distance cruising it increases the distance that can be covered in a given time. These days most of us have restricted time available - so multis can give us an unprecedented variety in our cruising experience.

Michael Storer
my boat pages (http://www.ozemail.com.au/~storerm)

[Doug Lord]

1)Canting keels can reduce the number of crew required on almost any monohull-big part of the attractiveness of the Schock 40.
2) Canting keels can improve the "rightability" of some big monohull designs like Open 60's.
3) I think you said that I was of the opinion that canting keel boats would beat normal multihulls. I do but only if the canting keel boats can be equiped with effective hydrofoils AND effective increased RM thru the keel strut. I do believe that SDB(sliding deck ballast) boats along somewhat similar lines of the Langman/ Bethwaite "Maxi Skifs" AND USING HYDROFOILS(bifoil "Moth" arrangement) can beat "normal" multihulls and even have a chance against three foil multifoilers.

[RHough]

For a given lift, the total area (of all elements) and the span of the longest element are used to determine the A:R of the system.

A single foil of area "s" and span "b" has an A:R of b^2/s. Splitting the area into two or more panels has no effect on total induced drag.

That's why we don't see canard or biplane gliders. You also don't see the area of wing-sail catamarans split into two foils of half span. The A:R of the entire lifting area governs the induced drag.

Two equal span and area foils is about the worst combination for the lowest total induce drag per unit lift you could possibly design.

No amount of trim change will reduce the induced drag of the two foils. Only changing the span will lower total induced drag.

The reduction in drag due to aligning non-lifting surfaces with the local streamline is real, but because the hull and bulb produce little or no lift, they have little or no induced drag. they have form drag and skin friction drag, but not induced drag.

So yes, reducing total induced drag by changing the trim of the foils is poppycock. It does not happen.

Do a Google on Munk and look at the math yourself. This has been proved fact for years.

[RHough]

2) Canting keels can improve the "rightability" of some big monohull designs like Open 60's.


Not if the reason that they are upside down is because the ballast strut sheared off (as it is designed to do on the Schock 40). :)

[Doug Lord]

No claim was made by me or CBTF for reducing the induced drag of the twin foils by changing their angle of incidence. Simply that the drag of the whole boat is reduced by the use of collective.
===
There is no question that the total drag of a CBTF boat going upwind NOT using collective is higher that one using it-thats my point. And a proven fact.If a hull ,strut and bulb are moving at a leeway angle(angle of attack) they most certainly DO develop induced drag. On a CBTF boat when collective is used that induced drag is eliminated.

[RHough]

No claim was made by me or CBTF for reducing the induced drag of the twin foils by changing their angle of incidence. Simply that the drag of the whole boat is reduced by the use of collective.
===
There is no question that the total drag of a CBTF boat going upwind NOT using collective is higher that one using it-thats my point. And a proven fact.

Oh really?

Actually, it's not. By using the collective the induced drag is substantially less than it would be if collective was not used. Thats the point.

Just thought you should know that someone is using your log-in. :)

[Doug Lord]

One of us is missing something. Why don't you try to explain your point again in case it's me.
==================
Is this better?
If you (wrongly) assume that when the twin foils are at 0° angle of incidence the hull,strut,and bulb make no contribution to the production of leeway resistance then there would be no difference in the induced drag developed by the twin foils regardless of their angle of incidence.
-------
Don't confuse angle of incidence and angle of attack.
--------
But, IF the twin foils are set at 0° angle of incidence the hull, strut and bulb do,in fact, unload them to some extent since the whole boat is moving sideways(to some extent).
Now, when the angle of incidence of the foils is changed the angle of attack of the foils remains about what it was before or slightly increases and they are loaded more do to the contribuion to leeway resistance from the hull,strut and bulb being removed. So the induced drag of the twin foils would increase slightly from the 0° angle of incidence setting to the +3° setting. But the induced drag of the boat as a whole would drop.
------

[RHough]

One of us is missing something. Why don't you try to explain your point again in case it's me.

In one post you said that the induced drag was reduced, in the other post you said you didn't say that.

Either you made both posts and forgot that you said "the induced drag is substantially less" before you said "No claim was made by me or CBTF for reducing the induced drag of the twin foils by changing their angle of incidence. Simply that the drag of the whole boat is reduced by the use of collective."

So, do I conclude that CBTF reduces induced drag some other way? The span of the foils does not change, the area of the foils does not change, how then is induced drag reduced? As I understand the system the foils only have freedom of movement in one plane. Collective has been described as the ability to change the AOA of each foils in relation to both the other foil and to the hull. Thus, any reduction in induced drag must come from changing the angle of incidence.

One of the posts is in error, or was made by someone other than yourself.

Making claims that are not possible does nothing to promote the CBTF foil idea.

Given the task of reducing induced drag any first year aerodynamic student would come up with something better that two equal span foils.

My point is that for a given span and area the induced drag is independent of the number of foils. Thus the total area of the 2 CBTF system foils would generate exactly the same lift and drag as one foil of the same span and area.

[Doug Lord]

See #145. I think the whole thing comes down to the fact that when I've talked about induced drag(for the most part) I've used it in reference to the whole boat in the 0° angle of incidence(no collective) case and for just the twin foils in the +3° case.
My whole point is based on the hull, strut and bulb unloading the twin foils a bit(and producing induced drag) in the non-collective case and then loading up in the +3° case with the total induced drag(of the boat) dropping from the 0° case to the +3° case.
Switching from the one case to the other may be confusing you or you don't accept that the hull,strut and bulb create induced drag in the 0° case. The fact that the hull, strut an bulb DO create resistance to leeway(lift) and therefore do create induced drag is the central theme of what I'm saying. Because in the 0° case when they are doing that they do it much less efficiently that just the twin foils do when collective is used(+3° case). In other words, at the 0° case the hull,strut bulb and twin foils create more drag to develop the same amount of lift developed by JUST THE TWIN FOILS in the +3° case.

[RHough]

See #145. I think the whole thing comes down to the fact that when I've talked about induced drag(for the most part) I've used it in reference to the whole boat in the 0° angle of incidence(no collective) case and for just the twin foils in the +3° case.
My whole point is based on the hull, strut and bulb unloading the twin foils a bit(and producing induced drag) in the non-collective case and then loading up in the +3° case with the total induced drag(of the boat) dropping from the 0° case to the +3° case.
Switching from the one case to the other may be confusing you or you don't accept that the hull,strut and bulb create induced drag in the 0° case. The fact that the hull, strut an bulb DO create resistance to leeway(lift) and therefore do create induced drag is the central theme of what I'm saying. Because in the 0° case when they are doing that they do it much less efficiently that just the twin foils do when collective is used(+3° case). In other words, at the 0° case the hull,strut bulb and twin foils create more drag to develop the same amount of lift developed by JUST THE TWIN FOILS in the +3° case.

Wrong again.

If the hull lifts and produces induced drag, then the hull area below the waterline gets includes in the total. The total area and the maximum span are uses to calculate induced drag.

If the lift from the hull is reduced to 0, the lift from the foils must be higher. The total lift remains the same, as does the total induced drag.

You are confusing the added area of the bulb and hull due to the leeway angle with induced drag. The induced drag is a product of lift, if the lift is constant, the induced drag is constant unless the planform changes.

As I said before, I don't doubt that aligning the underwater bodies with the streamline reduces drag. It just does not reduce induced drag. Since induced drag is orders of magnitude higher than the form drag, the gain from aligning the bulb and hull with the streamline is small.

These are basic concepts, you cannot fool mother nature.

[usa2]

Dont two equal sized foils make more drag than 1 single foil that is twice the size of them? The wetted surface drag is the same, but thats not the only variable involved.

[Doug Lord]

"....unless the planform changes." There you go- right almost. In essence, the planform DOES CHANGE between the lift being developed in the 0° case and the lift being developed in the +3° case.
-------------------
In the 0° case lift is developed by the hull, the strut, the twin foils and the bulb.The portion of the total lift developed by the hull,strut and bulb is done very inefficiently compared to that developed by the foils but in this case they all contribute to lift.So there are five contributions to induced drag in this case:1) the forward foil,2) the aft foil,3) the hull,4) the strut,5) the bulb.
----------------------------
In the +3° case only the foils develop lift and very efficiently compared to the 0° case.Only the twin foils contribute to induced drag in this case.
----------------------------------------
The total of induced drag in the second case is less than the total of the induced drag in the first case.
==========================
The clearest possible explanation can be found by isolating the keel strut which on a CBTF boat is not designed to develop lift. But when the twin foils are aligned with the centerline of the boat thats EXACTLY what the strut is doing! It is being asked to operate at the leeway angle which gives the strut section an angle of attack which creates a large amount of drag! Same with the bulb ;same with the hull.In the 0° case,if you don't look at the hull ,bulb and strut as lift producing foils you're making mistake.

[RHough]

"....unless the planform changes." There you go- right almost. In essence, the planform DOES CHANGE between the lift being developed in the 0° case and the lift being developed in the +3° case.

The planform is the span and area. Since the neither the area or the span changes, the planform does not change.

In the 0° case lift is developed by the hull, the strut, the twin foils and the bulb.The portion of the total lift developed by the hull,strut and bulb is done very inefficiently compared to that developed by the foils but in this case they all contribute to lift.So there are five contributions to induced drag in this case:1) the forward foil,2) the aft foil,3) the hull,4) the strut,5) the bulb.

Correct, the total lift = Cl x Area x Density x Velocity^2

Since all 5 components contribute lift, the area of all 5 components is included in the area.


In the +3° case only the foils develop lift and very efficiently compared to the 0° case.Only the twin foils contribute to induced drag in this case.[QUOTE]

The total lift and total area have not changed, only the distribution of that lift. Some areas produce less lift and drag, other areas have to produce more lift and drag. The total lift and total induced drag do not change.

[QUOTE=Lorsail]The total of induced drag in the second case is less than the total of the induced drag in the first case.

Absolutely and totally wrong. To produce the same lift a given area and span will have the same induced drag. 1 area or 5 or 10.

Induced Drag = CDi x Area x Density x Velocity^2

The Area did not change, the Density of water did not change, the Velocity did not change. The Coefficient of induced drag (CDi) is the only thing that could have changed.

CDi = CL^2/(PI x AR x e)
Where
AR = Span^2/Area
e = Oswald efficiency factor

Lift = CL x A x D x V^2

So for the same lift force and area the CL does not change.

Pi does not change

The span and area did not change, so the AR did not change.

e is a factor that compensates for the gap between surfaces, since the gap did not change, e did not change.

Since none of the factors that go into induced drag changed, the CBFT boat will have the same induced drag at any trim angle of the foils.

Don't argue with me, call tspeer or NASA or anyone that has more than a basic grasp of aerodynamic theory. What you state cannot happen.

What happens is the total angle of leeway measured through the hull centre line changes. The high AR foils need only a fraction of increased angle to compensate for the loss of lift from the hull. The total induced drag remains the same only the angles are changed.

There is no free lunch.

If the CBTF crew have changed the laws of physics it would work, but I doubt that they have.


The clearest possible explanation can be found by isolating the keel strut which on a CBTF boat is not designed to develop lift. But when the twin foils are aligned with the centerline of the boat thats EXACTLY what the strut is doing! It is being asked to operate at the leeway angle which gives the strut section an angle of attack which creates a large amount of drag! Same with the bulb ;same with the hull.In the 0° case,if you don't look at the hull ,bulb and strut as lift producing foils you're making mistake.

Please do some math, pretty please?

Please provide some numbers that show the relationship between hull and or strut angle and drag.

Break it down into it's component parts:
Skin Friction Drag (changes linear with wetted surface)
Profile or Form Drag (Changes with cross section shape)
Induced Drag (Drag due to Lift)

Skin Friction going to change much? What effect does changing the angle of the hull have on wetted surface? The strut and bulb are under water (we hope) so their surface area remains constant.

Profile Drag? Assume the bulb and strut have low drag shapes. How much does the profile drag change when the AoA changes +/- 5 degrees from the minimum drag angle?

What portion of the total drag of the hull and appendages is due to each of the three?

How much will the total drag change by the change in angle of low drag bodies and any change in hull surface area?

You will find that profile or form drag does not change very much within 5 degrees of the ideal angle. The hull, strut and bulb never have a constant angle to the streamline for any length of time. Every gust heels the boat and the strut and bulb have an angle of attack while the heel angle is changing. Pitching movement through waves also changes the AoA.

Don't just quote what you've been told, do some math for yourself and try to prove what is claimed. It cannot be done.

Just because someone gets a patent based on their claim does not prove the claim. Anyone can get a patent. Take a look at the absurd patent thread

Enough with the smoke and mirrors.

[RHough]

Dont two equal sized foils make more drag than 1 single foil that is twice the size of them? The wetted surface drag is the same, but thats not the only variable involved.

Two equal area foils of span "x" will have the same lift and induced drag as a single foil of the same area that also has span "x"

If the two foils are combined into one foil that has eqaul area and span = 2X the AR will be higher so the induced drag for the same lift will be lower.

2x10=20 20x2foils = 40 each foil has A:R = 5:1 The combined foil of area 40 and span 10 has A:R = 2.5:1

A single 2x20 foil has area = 40 and A:R = 10:1

For the same lift the higher AR foil has less induced drag for the same surface area.

[Raggi_Thor]

If you use leeway to create the lift, then you have induced drag also from the bulb and it's strut. With minimized leeway this drag should be very small. I think this is the most important difference. Sometimes amateurs building boats with rotating keels claim that they will sail higher. That is probably not the case, but they will sail (a little) faster :-)

[RHough]

If you use leeway to create the lift, then you have induced drag also from the bulb and it's strut. With minimized leeway this drag should be very small. I think this is the most important difference. Sometimes amateurs building boats with rotating keels claim that they will sail higher. That is probably not the case, but they will sail (a little) faster :-)

Correct, they will sail no higher. They may sail at different leeway angles (point higher).

The total induced drag does not change, since the lift requirement does not change.

The major underwater drag producers are Induced drag from lift, Parasite drag from skin friction at speed/length ratios below 1, wave making drag at S/L ratios above 1, and the smallest drag producer is profile or form drag.

I suspect that wave making resistance of a hull is higher when it is moving through the water at a yaw angle to the direction of travel. I don't have any experience trying to quantify the effect of yaw on wave so I won't post an opinion on the possible magnitude of drag reduction available.

[Vega]

Back to Canting keels, it looks that the VOR70 have shown a set-back of the system (not mentioning reliability). It looks to me that when the boat is surfing down a wave, the almost horizontal foil of the keel will produce an enormous hydrodynamic force, pushing the bow down. That's dangerous.

The obvious way to solve that problem would be by using a pivoting keel which would allow to control horizontally that foil (the keel). That way you could have a very good control of the boat when surfing big waves.

Of course....that will be even more complicated....more electric engines, more power to run the boat..:rolleyes:

[D'ARTOIS]

Obviously, nobody thought of the bycoming effects just as Paulo just mentioned. En plus, I was thinking of another event that might be a source of problems within the construction of the canting keel suspension. ( Do we call it a suspension?)

The struts are designed and engineered in such a way that they have a minimal wetted surface. The pivot (hinge) is very high up leaving a long and tremendous heavy arm working against a short arm that is hydraulically powered to move the keel to the two boards.

The boat is without interruption subject to the violent movements of the sea and also the keel must transmit heavy vibrations caused by the thin fin (strut) finally causing damages to the hydraulic system.

Vibrations that also influenced negative impacts on the attachment of the webframe monted in the hull, with all the stresspoints located on 1,5 sq. metres; without an equal spread of all those forces along the hull.

[Doug Lord]

This discussion started to illustrate why a CBTF boat performs better upwind than a canting keel boat with a single fixed daggerboard. To illustrate this I chose the example of one CBTF boat with both twin foils on the centerline, the 0° case. The other example was the same CBTF boat with the twin foils turned to an approximate +3° angle of incindence. In the 0° case the whole boat contributes to the development of lateral resistance(lift) and consists of these elements:1) the forward foil, 2) the hull,3) the strut,4) the bulb and 4) the
aft foil. In the +3° case only the twin foils contribute to lateral resistance(lift).
Just for the hell of it lets give each of these components some numbers corresponding to their planform area:1)the forward foil=12 sq.ft.,
2)the hull=120sq. ft.,3) the strut 21.6'sq.ft.,4) the bulb 18 sq.ft. and the aft foil 12 sq.ft.. Total area =183.6sq.ft.
According to Munks theorem if you have multiple LIFTING surfaces lined up in the streamwise direction, the drag due to lift(induced drag) is the SAME as a single surface of the same span with it's lift distributed the same as the total of all multiple surfaces. Doesn't matter how the lift is distributed between the multiple surfaces or how far they are separated.(paraphrased from Tom Speer)
Effective aspect ratio is the max span(depth in both cases) squared divided by the total area.
---------------------------
0° case(hull+ foils +strut+bulb lifting) : total area 183.6 sq.ft; max span(wl to bottom of bulb)=16'. Span squared(256) divided by total area(183.6)= an effective aspect ratio of 1.39 .
-----------------------------
+3° case-(only the twin foils lifting) : total area=24sq.ft.; max span=10'. Span squared(100) divided by total area(24)= an effective aspect ratio of 4.16/1 .
==============
This shows ,again, that the 0° case has lots more induced drag than the +3° case since the higher the effective aspect ratio the LOWER the induced drag. This is an illustration of what actually happens in the real world between two identical CBTF boats going upwind ,one with the foils on the centerline and one with the angle of incidence adjusted so that the foils develop all the lateral resistance. It illustrates why a fixed symetrical, forward foil at 0° angle of incidence with respect to the centerline of the hull on a canting keel boat is the worst possible solution.

[RHough]

Just for the hell of it lets give each of these components some numbers corresponding to their planform area:1)the forward foil=12 sq.ft.,
2)the hull=120sq. ft.,3) the strut 21.6'sq.ft.,4) the bulb 18 sq.ft. and the aft foil 12 sq.ft.. Total area =183.6sq.ft.
<snip>
---------------------------
0° case(hull+ foils +strut+bulb lifting) : total area 183.6 sq.ft; max span(wl to bottom of bulb)=16'. Span squared(256) divided by total area(183.6)= an effective aspect ratio of 1.39 .
-----------------------------

To continue ...

Assume:

The total Lift required is 1000 pounds
The boat speed is 25 ft/sec (about 15 knots)
The span effeciency is 100% so e=1
The density of water is 1

Case 1

CL = 1000 (lift)/(183.9 (area) x 1 (density) 25^2 (velocity squared) = .00814

CDi (Coeffienct of induced drag) = CL^2/(pi x AR x e) or in Case 1

CDi = .00814^2 / ( pi x 1.39 (AR) x 1 (100% span effeciency) = 0.0000173

Thus induces drag = 0.0000173 x 183.9 (area) x 1 (density) x 25^2 (velocity squared)

Drag = 1.989 pounds



+3° case-(only the twin foils lifting) : total area=24sq.ft.; max span=10'. Span squared(100) divided by total area(24)= an effective aspect ratio of 4.16/1 .
==============

Lift = 1000
Area = 24
AR = 4.16

CL = .0667
CDi = 0.000339
Drag = 5.093 Pounds


This shows ,again, that the 0° case has lots more induced drag than the +3° case since the higher the effective aspect ratio the LOWER the induced drag. This is an illustration of what actually happens in the real world between two identical CBTF boats going upwind ,one with the foils on the centerline and one with the angle of incidence adjusted so that the foils develop all the lateral resistance. It illustrates why a fixed symetrical, forward foil at 0° angle of incidence with respect to the centerline of the hull on a canting keel boat is the worst possible solution.

Since the 0 degree case using your numbers and known formulas has 2 pounds drag and the 3 degree case has 5 pounds drag what is shown?

That twin foils more than double the drag?

Please check my math. :)

[Doug Lord]

Randy, thanks for your help in understanding this. I was certain that the induced drag between the two cases was different ; I just expected it to go in the opposite direction! Thats ok because I find this fascinating and will learn (soon) what the missing factor is. I know there is one because when two identical CBTF boats sail upwind together the one using collective is faster(+3° case). I just don't know how to show that yet but I'm learning.
I'm fairly confident that the Oswald span efficiency factor"e" is the missing link and I suspect that e for the 0° case would not be 1 but something between .5 and .7 since lift distribution for the majority of the area is poor.For the +3° case, at this point it appears that the lift distribution would allow an e of 1. May have to increase foil area a bit too I don't know yet. But the facts appear to be that induced drag can be different for two different systems producing the same lift which I've thought I understood for some time. But I've got a ways to go to find this missing factor so that the formula's results correspond to the facts on the water but I'm looking....

[RHough]

Randy, thanks for your help in understanding this. I was certain that the induced drag between the two cases was different ; I just expected it to go in the opposite direction! Thats ok because I find this fascinating and will learn (soon) what the missing factor is. I know there is one because when two identical CBTF boats sail upwind together the one using collective is faster(+3° case). I just don't know how to show that yet but I'm learning.


My guess is that at lower speeds the difference is not great. But as Wave making drag starts to dominate, the drag reduction comes from a combination of the hull making smaller waves and the change in pressure at the forward foil station reducing the size of the bow wave further.

Relatively simple Aerodynamics does not predict any change in the induced drag from lift. Altering the size and shape of the bow wave would have a huge effect. Since these boats are sailing upwind at S/L ratios of over 1.1:1, they are starting to push into the forced mode.

The whole hullform vs wave drag thing is WAY beyond my knowledge level. I know enough Aero to design planes that fly, but as someone stated in another thread, "Designing airplanes is easy compared to designing sailboats, airplanes only have to fly." :)

I do know that the ideal shape for a glider fuselage "looks" wrong and the nose should droop to align with the streamline of the upwash ahead of the wing, rather than align with the flight path. It could be that giving the forward foil an angle of attack puts the forward part of the hull more inline with the upwash ahead of the foil?

I'm stumpped. :(

[Doug Lord]

It's definitely complex but in the example above we're talking about two identical boats(and ,to some extent,about a fixed forward foil on a"normal" canting keel boat.) With two identical CBTF boats the foils are placed in the high pressure area of the hull(according to CBTFco) and the benefits of wavemaking drag reduction should, I would guess, accrue to both boats. Whereas only the +3° case eliminates leeway. I'm going to keep working on it....
edit: I tried running the numbers above with a different(.52 and .7) "e" in the 0° case and it makes the difference(also increased foil area ) . I have no idea what an accurate "e" factor for the 0° case would be-maybe CBTFco will help me with it.....

[RHough]

Hey Doug,

We're way off topic. I sent you a PM.

Randy

[Doug Lord]

Randy, the topic is a discussion of "Canting Keels in Production Yachts" and our exchange began more or less with the MF 35 when I wondered why they would have used a fixed forward foil -the slowest choice for a canting keel boat. We may be boring some but it just takes one person to bite into this and help explain the situation.The CBTF guys may even look in here so I think we're "on topic" just kinda heavy into the technical aspects. I think your PM has relevance- as does this discussion- to the original topic .

[guit]

Although your calculations require some attention while reading, I agree that it is not off topic. Since the CK is a nice way of enhancing performance and ballast distribution the techniques around it might be optimised as well. Any arguments are welcome here, and numbers are harder then opinions.

But in smaller production yachts in the (god save me...) cruiser/racer group, interior space is of some importance. The CK-mechanism is a problem, but might become quite flat so a slightly higher floor could solve that. Any lifting (daggerboard) mechanism will be far more costly when it comes to interior space.

Therefore I would recon that there is little future for a PRODUCTION YACHT with canting keel and movable daggerboard(s). I reason that a yacht big enough to accommodate such a mechanism is (semi-)custom and cannot be considered a "production yacht".
Any mechanism with daggerboard(s) might find it's way into smaller OD-classes, where interiour space is less important.
But hey, this is just what I'm reasoning here.

ps. The MF35 has a canting keel and a retractable (carbon fibre whoho!) daggerboard, I'm not sure if that was mentioned...

[Doug Lord]

I'm 100% convinced -at least for the time being- that CBTF is the fastest canting keel system. But for prodution yachts the kFOIL may offer the best solution: it using a retractable foil mounted in the bulb and requires no invasion of space inside the boat for an extra foil. Another solution (though not as good as the kFOIL in my humble opinion) is Andy Dovell's use of fixed wings on the canting keel bulb. Julian Bethwaite has recently changed the keel design on the 79er from a bulb molded in the shape of a wing(like Procyon years ago) to a bulb with fixed wings similar to Dovells pioneering work.Unfortunately neither Dovells nor Bethwaites wings retract but
and they can break off-it happened with Dovell.The new Backman 29 has foils on the bulb "that are controlled by hydraulics" but there is no info yet on WHAT (angle of incidence,sweep angle, retractability??) is controlled.
The kFOIL will retract if it hits something so it has current lateral resistance solutions beaten on room inside, safety, and retractability.
kFOIL™ :
http://www.sailinganarchy.com/editor/2004/edword_october2004.htm

[D'ARTOIS]

I owe Doug Lord an apology when I said that he was wrong and that the canting keel only just the last 3 years excisted.
This is not true.

Baltic seems to use this system considerably longer in their larger boats and so are there another small number of shipyards that use the canting keel in their production boats considerably longer than I actually thought to be true.

I came just back from Duesseldorf Boatshow where I had the time to talk to several yachtbuilders who confirmed that the canting keel is at least 7 years in use in some - larger - production boats and tend to have, or induce no problems.

So I was definately wrong in my earlier statements.

Therefore my apology to Doug Lord!

[Doug Lord]

Apology accepted, D'artois-but it's a lot longer than 7 years....

[zzmeyer]

The best part of a canting keel is when they fall off. Raced against a Schock 40 with for and aft rudder and a canting keel last weekend. When the keel fell off the boat went turttle and we beat the heck out of them - no one was injured.

[Doug Lord]

Too bad about that-been following the gibberish(mostly) about that accident on SA-do you know anything(factual) about what caused the keel failure?
Have you raced them before?
CBTF is good ,fast technology but Shockazulu had the exact same thing happen two or three years ago and ,I think, is the only Schock 40 to have such a failure.

[zzmeyer]

I don't. They were ahead of us and we just saw the results. Talked to one of the crew. Said they didn't hit anything. Boat went over "like a laser in a puff". Wind was gusty, but nothing over about 18knots.