Canting Keel Monos vs Multihulls

Discussion in 'Multihulls' started by brian eiland, Aug 31, 2006.

  1. Doug Lord

    Doug Lord Guest


    ONCE MORE:For those that say I hijacked the thread-you are JUST PLAIN WRONG. See the highlighted question below and note that in almost EVERY POST I've made I attempted to answer that question. You may not like or agree with my answer but the fact is that it is RELEVANT to this thread and further, that I provided information showing that others are working along the same lines I proposed.
    The initial reaction was -canting ballast has no chance against multihulls-well I beg to differ! I apologize to the intelligent readers of this forum that any mention of "foils" in any context draws obnoxious personalattacks and just plain silly BS from a small group that couldn't intelligently discuss the subject of this thread if their lives depended on it.

  2. Chris Ostlind

    Chris Ostlind Previous Member

    The Hijacking Gambit

    You haven't shown that anyone is actually "working on the issue" as presented. What you have shown is that there have been a few pretty pictures of hypothetical boats drawn and that's it. Much like the overly hyped and non-existent AeroSKIFF project, there is absolutley nothing to show for the references to the two illustrations. The Out95 is the only working craft that has even any remote resemblance to the process and it's not exactly a screamer in competition, now, is it? I'm sure it is fun to sail, but at what cost and to what delivery of dominant performance? Go look at their race results to get an idea as to how dominant the boat actually isn't.

    The Out95 does not wear foils and all there is to talk about is the hypothetical potential of the addition of foils out in the future at sometime. How that plays as germane to the thread is beyond my logic stream. I would suggest that you are reaching for straws on the topic.

    Right now, it looks like the boat is suffering from the same thing that has beset the AeroSkiff... too much hype and not enough substance. BUT... at least they have a boat to sail and they are learning what works and what doesn't, which is already miles ahead of anything not happening on that other wispy project.

    So, you want to put foils on a boat with a heavy, canting keel and call that the solution? I say it's a bundle of technical stuff just asking for a huge onset of problems. The foils are going to lift the hull, rig and the crew and their gear, but also the canting bulb. Maybe we should be asking Ilett how big and how strong the foils will need to be on that type of boat and whether the drag from the appendages that are sized appropriately for the task will actually be able to lift the boat under sail power?
  3. Doug Lord

    Doug Lord Guest

    Foiling Canter-"future of canting ballast development?"

    Langman says words to the effect that someday even his 98 footer will sail on foils.
    Sailing Anarchy InnerViews Sean Langman 2005
    Address: Changed:11:02 PM on Sunday, October 23, 2005
  4. RHough
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    RHough Retro Dude

    Let's add some documented facts:

    Up to 60 foot.
    1994 "Primagaz" 60ft Tri, Laurent Bourgnon, FRA, 540nm. 22.5kts
    2006 "Mediatis-Region Aquitane" 60ft Cat, Yves Parlier FRA and 5 crew 597.81nm. 24.91 kts
    2006 "Brossard" 60 ft Tri, Yvan Bourgnon SUI, 610.45 nm. 25.76 kts

    Monohull, up to 60 foot.
    2000 "Union Bancaire Privee" 60ft, Dominique Wavre, FRA, 430.7nm. 17.94kts
    2003 "AT Racing" 60ft, Alex Thompson, GBR, 468.72nm. 19.53kts

    Equal length = 60ft

    Multi 141.73 nm further in 24hrs
    Multi 6.23 knots faster (24 hour average)

    That would be 31.89% faster.

    I include the 1994 number to show that a 60 mono has yet to best the speed. The 2003 mono is only 15% slower than the 1994 multi ...

    2006 "Orange II" 120ft Cat, Bruno Peyron, FRA, 766.8nm. 31.95kts

    2006 "ABN AMRO TWO" 70ft, Sebastien Josse, AUS, 562.96 nm, 23.45kts

    Multi is 8.5 knots faster (24 hour average)

    That would be 36.25% faster.

    Please cite sources for the 40+ knot speeds of a VO70 or G-Cat.

    They certainly do not reach those speed for any significant length of time.

    40+ knots for less than the 90 seconds it take to cover 1nm? Those boats are recording data all the time. If the data track showed 40+ for 90 seconds they would qualify for the 1nm speed record.

    The 500 metre record is 48.7 and the 1 nm record is 39.97, if either the VO70 or G-Cat could prove 40+ knots they would be record holders. They hold no such record.

    As I said, at some small size, under some conditions, a foiling mono might be faster than a non foiling multi. But so what? In any racing environment the rules should not favour one design over another. Thus, if the mono is allowed foils, the multi should be allowed foils and the multi will be faster.

    Rulemakers have been writing rules to favour pet designs for years. Doug's rule: I want the moving ballast, foiling (or foil assited) boats I like to win, so I won't allow multi-hulls to use foils.

    In any open rule race, mono's just don't fare well. It has been proved time and again. The only way mono's can win is if multi's are not allowed to play.
  5. Doug Lord

    Doug Lord Guest

    Open 60 canting keel monohull

    Read the previous posts for sources of speed information. On page 62 Sail mag Sept. says that top speed hit by an Open 60 is 30 knots-appears that some 60' mono's are already faster than some 60' cats....if you believe Sail Magazine, of course!
    Too many brilliant people are working on the combination of foils and canting keels for someone at some point not to prove what I've been saying in this thread and for years....
    And it damn sure answers the question posed in the first post of this thread.
  6. RHough
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    RHough Retro Dude

    That boat doesn't qualify ... it's a Trimaran. Your rule is that multi hulls are not allowed foils.

  7. Doug Lord

    Doug Lord Guest


    Multi with a canting ballasted keel, huh?
    Geez, those are buoyancy pods used only for emergency backup and are not sailed on at any time. Of course, it would be smarter to make sure the pods did not in any way resemble hulls for the sake of being classified as a mono-I'll grant you that. He could design pods that effectively did the same thing but were more similar to the buoyancy that is class legal in the Moth class.
    Even though the boat is a monohull keelboat- that particular incarnation of buoyancy pods is an open invitation for people like you (and rule administrators) to call it a trimaran. But as you will soon see it doesn't have to be done that way.....
  8. Chris Ostlind

    Chris Ostlind Previous Member

    Let's try this again

    That is not a real boat, Doug. It's not even close to becoming a real boat any more than the two illustrations shown below. Hypothetical is not the same thing as actually doing it.

    Since you live in Florida and are smitten by all things technical, perhaps you can remember when scientists promised us that one day we will travel to the stars that are millions of light years away? They even drew-up some fancy renderings of just what such a ship should look like. Well, billions of dollars later and a world of well wishing Trekkies in their jammies haven't brought us any closer to warp speed sessions with bubble hairdo'd mommas in heels.

    I really do like that you have a such a kid-like quality about you that you can continue to hold-on to the dreamy prognostications of a twelve year old's mentality, but it isn't really gonna happen just because someone out there took the trouble to do a rendering. You need to get over that day dream and get on with it, my boy.

    Go look at the pages of to see a world of stuff that has flown out of some dudes noggin in an attempt to worship at the alter of high technology. Some of them even progressed to the sorta-working prototype stage because they had access to money and no sense as to how to use it. Of those that did get that far, just how many are out there as successful commercial representations of world shaking ideas?

    Dude, get yourself grounded and your nose out of the pages of Popular Mechanics Magazine. Take your enthusiasm and direct it towards a venue that works in this time and place and most of all... do something with your time on this planet besides beating the same note on the same tired little drum.

    You have a lot to potentially offer the boating world, but this obsession with all things being solved through foiling and technology is not the way to get it done.

    Along those lines, it's time for me to go to the shop to finish building the trimaran that is already sold.

    Attached Files:

  9. Dan S
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    Dan S Junior Member

    Doug this is the same old shi* you did back on the rc sailing forum. You post what ever mindless drivel you come up with, and then expect everyone to take your word for it. Should i go and find some wonderful exapmples to prove my point?


    just because you read someones opinion in a magazine, a blog, a website, etc. doesn't make you an expert on a subject. So the fact that you "beg to differ" has no bearing, because you opinion is worthless.
  10. RHough
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    RHough Retro Dude

    Yup ... to slow it down. Kind of like the foil on Langman's Grundig:

    "The bow foils we fitted to what was then Grundig were really a mechanism to try and stop the boat from nosediving. The boat is quite wide-sterned and quite straight, once she accelerates to planing speed she tends to nosedive into the wave in front. This is really a function that waves basically go at 20 knots and the boat is trying to do faster than 20 knots, so we were looking at means to try and keep the bow out of the water. It’s more of a speed limiter than making the boat go faster. "

    If they used the weight of the lead, strut, and the machinery that moves it to make the amas bigger, the boat would be faster. Hauling lead around is not a speed producing feature ... unless rules require it (by banning multi-hulls).

    The limit to canting keel speed will be draft. Since the keel has to swing from side to side. 50 feet or so would allow the boats to sail in all the same places that are open to container ships.

    Can we agree that SCP to total weight is the indicator of speed potential?

    If so, our two equal length boats will weigh the same and have the same sail area. The boat with the higher RM will win.

    Lets build a Retro 98 foot Cat.

    Weight 35,000#
    Beam 60 feet

    One hull maybe 40% of the total? 14,000#

    So we have 14,000# at 60ft plus 7,000# at 30 feet(crossbeams and rig) for a total RM of 1,050,000 lb/ft

    Let's say the 98foot Mono has a 14,000# hull and a 2,000# rig, that leaves 19,000# for ballast

    To equal the 1,050,000 lb/ft of RM that the cat has, the ballast must move 55 feet to windward. At 45deg cant, the ballast strut has to be 78 feet long. The boat would need 80 feet of water just to tack.

    How is a canting keel boat with reasonable draft ever going have the power to beat a multi?
  11. marshmat
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    marshmat Senior Member

    RHough, I noticed in your little example you are accounting only for weight and ability to carry sail. In practice, drag will be a big factor too. The multi will have one narrow hull, one rudder and possibly one daggerboard in contact with the water. The mono will have one wide hull, at least one rudder, and in the case of a canter, both a daggerboard and a ballasted keel in the water. More stuff in the water = more drag.
    Now put both boats on foils (it wouldn't be fair to put only one on foils). The mono now has the added complexity of moving ballast in air, or else has the added drag and complexity of moving ballast in water, and still doesn't have the RM of the cat.
    For outright speed, multis rule just about everything. Monos have their advantages elsewhere- living space, ability to self-right, cheap marina fees, etc. that make them great cruising boats, but as far as maximum velocity is concerned, cats and tris inherently have a big advantage.
  12. Doug Lord

    Doug Lord Guest

    Question: "What is the future of canting ballast technology?"

    Juan K chose to answer that question socio-politically I guess you'd say; I've tried to answer it technically. What some here don't seem to get is the word FUTURE in the question. While it is impossible for anyone to know the future some of us who have spent years studying multihull design, canting keel technology and the application of hydrofoils to monohulls and multihulls can make educated, well informed GUESSES as to what the future of canting ballast technology might be. That's why the work of Sean Langman , Andy Dovell and Julian Bethwaite is relevant to this discussion. Bethwaite has designed a Maxi Skiff that has tremendous potential using on-deck movable ballast on a 60 footer giving much greater RM at less weight than than using only a conventional fixed or canting keel. Langmans Maxi Skiff utilizes not only a canting keel but , with Andy Dovell, he is looking at the application of hydrofoils to large monohulls.The Out 95 guys have proven in their first few months that their unigue boat at 32' is the match of 40 and 50 foot boats such as the Libera class-at least some of the time and not using foils any of the time. As their program progresses their plan is to experiment with foils- a two foil bifoil system. This kind of thinking and exploration is bound to lead to a whole new generation of monohulls and quite possibly to speeds at least equal to current multihulls the same length. Remember, Sail magazine says that the gap in top speed between the VO70(70') and a 100'+ G-Class cat is only 5mph so mono's with canting keels are already almost as fast as multies-at least some of the time....

    Mr. Hough, in my opinion, the first premise of a canting keel monofoiler is that it is defined -by everyone- as a monohull. That probably means "poitically correct" buoyancy pods that don't look or function like hulls. It most certainly means that the boat must be selfrighting from a capsize or pitchpole. The ballast located in the canting bulb/strut combination must be enough to right the boat but no more. Additional RM as needed to sail in the same pressure an ORMA 60 sails in to fly the main hull must come from on -deck sliding ballast(such as a sliding water tank) as proposed by Bethwaite.
    SCP to total weight is NOT a good indicator of multihull to monofoiler performance as proven time and again by the Moth; multi's with numbers well over the Moth number are routinely beaten by the Moth in conditions suitable to both boats.
    A 60' monofoiler can be shown to have more(40%) SA per sq.ft.of wetted surface than an ORMA 60 tri that is flying the main hull and itself supported 60% by a banana foil and 30% by the leeward ama even though the monofoiler is heavier.The monofoiler has a much greater margin of superiority in SA/wetted surface compared to a conventional multi not using "foil assist" as does the ORMA. The downside is that off the foils the ORMA tri would reverse that advantage. However, the monofoiler would probably fly in 8-10knots of wind. And the monofoiler would be selfrighting...
    All the information that's been posted here regarding the combination of foils and movable ballast proves that ,at the very least, this is an area fraught with potential in any consideration of "the future of canting ballast technology" as the question was phrased in post #1 of this thread.
  13. RHough
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    RHough Retro Dude

    Doug, just once compare apples to apples.

    If a canting keel, moving deck ballast boat can foil in 8-10 knots of wind (a VERY big IF), so could a foiled multi hull.

    Once foiling, the SCP/Drag ratio is the speed limiter. The question would become: Would a hull and two foils plus the surface piercing ballast strut have more or less hydro drag than just the two foils? You have stated in no uncertain terms that adding a third surface piercing element increases the drag 33%. (I don't believe it, but that's what you said).

    With greater SCP available and less drag the multi has to be faster.

    The other drag component is aero drag. The aero drag of the ballast outrigger and support structure would have to be about 3% of the cross beams and windward hull of the multi (since water is much denser than air).

    Since the multi has less hydro drag and greater SCP, the rig could be smaller than the canting/sliding mono, another reduction in aero drag.

    It is also time to define "self-righting". Self righting to me is that from a capsize in any sailing configuration the boat will self right without any action taken by the crew. I very much doubt that the canted keel, sliding deck ballast boat could be made self righting by that definition.

    Once we allow the crew to take an active role in righting the boat by shifting ballast or whatever means, the multi could be made "self-righting" also.

    The fact remains when you compare two 98 foot boats, the combination of canting ballast and deck ballast has to at least equal the 1,050,000 lb/ft of the cat. Assume that 5,000# is enough to provide "self-righting". Lets assume a 45deg cant angle and 15 foot draft. That gives about 53,000 lb/ft of RM leaving only 997,000 lb/ft to be provided by the sliding deck ballast of 14,000. Lets take your word that the "mono" can be heavier and faster and give it 20,000# of sliding ballast ... now all you have to do to get the same RM is move 20,000# 50ft off the side of the boat.

    Give the boat a target of going from full power on one tack to full power on the other tack in ... 12 seconds ... assume zero friction ... how much HP will it take to move 20,000# 100 feet in 12 seconds?

    This is very simple math, we have not even started to look at the engineering that it would take to move that much ballast and the structure needed to support it.

    How many gallons of water does it take to get 20,000# ? 2500? That means rolling 45 55gal drums 100 feet on each tack?

    No one wants to talk about the wave height issue? What happens to the foiler's drag advantage when waves start hitting the hull?
  14. Doug Lord

    Doug Lord Guest


    In my comparsion above I showed that the sa/wetted surface ratio of a 60' monofoiler compared to a 60' ORMA tri was in the favor of the heavier monofoiler when both were going near max speed in approximately 2lb. pressure( approximately the pressure required to fly the main hull of the tri). And I believe that's realistic.
    The ORMA is designed to have part of the ama immersed because the ama immersion is what most of the ORMA boats rely on for pitch stability-only one or two use a rudder t-foil. In these conditions on the monofoiler the canting strut would be at max cant and completely out of the water.The ORMA has part of a hull, parts of two rudders, a lifting foil and part of a daggerboard in the water. The monofoiler has just the two main foils, part of one rudder and part of one daggerboard in the water.The rudimentry evidence suggests that the monofoiler would have 40% more sa per sq.ft.of wetted surface than an ORMA Tri. .And that SA/wetted surface comparison is with a heavier monofoiler with 16% less SA than the ORMA tri.(which is part foiler and NOT a conventional multihull)
    My point is that a canting keel+on-deck ballast monofoiler stands a real good chance of being at least equal in speed to a conventional multihull-and maybe faster but definitely NOT faster than multifoiler!
    The suggestion was made early in this thread that a canting ballast boat could never be as fast as a multihull-that's just not true, in my opinion. If what I say(and many others believe as well)is true then multihull speeds with the added advantage of self-righting may be just around the corner.
    Most especially if you believe what Sail magazine says showing the Vo70 with a canting keel is just 5 knots short of the top speed of a 100' G-Class cat! That means that a 70'canting keel monohull would only have to go 12% faster to EQUAL a much large multi....
    I think it's possible to do that with carefull state of the art design combining canting keel technology with on-deck movable ballast and hydrofoils-time will tell.

  15. RHough
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    RHough Retro Dude

    What draft? At 15 feet of draft for the canting strut and a 45deg cant angle you need to get the hull 11 feet off the water to dry out the bulb. The T-Foils would have to be deeper than that to stay immersed with the bulb out of the water ... now add 6 foot waves ... just what are the foils going to be made of? All they have to do is support a 35-40,000# boat 11+ feet off the water at 35+ knots ... should be easy ... :rolleyes:

    The numbers don't add up Doug.

    You talk about in the future ... like when we can harness anti-gravity? When the laws of physics are repealed?

    I have a very active imagination too, but I cannot come up with a design that meets the criteria you bandy about that also obeys the laws of physics on the surface of planet earth.

    Until you can come up with some numbers that support your claims I'll remain a skeptic.

    A foiling multi with only two foils in the water would have the same wetted surface to SA ratio as the "Monofoiler" it would only be a "Multifoiler" when the windward foils are immersed ... kind of like Langman's boat being a mono-hull except when the training wheels are wet ... :D

    By your own twisted logic it is fair to compare boats in conditions that they don't always maintain. I love the hair splitting ... calling a boat with two foils a mono-foiler and calling boat with 3 or more foils a multi-foiler ... The "Mono-foiler with the ballast strut in the water has three foils, thus is a "multi-foiler" by your definition, it only becomes a "Mono-foiler" after the ballast clears the water. How is that different from a catamaran configuration that is only a "multi-foiler" until the windward hull and foils are flying ... then it becomes a "Mono-foiler".

    The ballast bulb will be fully canted clear of the water only a small part of the time, just as the windward hull of the foiling multi will be clear of the water some portion of the time.

    Since you keep repeating that the as yet un-built future CKSDBMF (Canting Keel Sliding Deck Ballast Mono Foiler) MIGHT be as fast or faster than current non-foiling multi-hulls, what's the point? Are you saying that a dog with three legs can outrun a dog with two legs? Then we have no argument.

    Why don't you put your considerable talent (no joke, as I've said before I think Doug is a clever guy) to making multi-hulls self righting rather than trying to come up with new ways to move lead around?
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