Canting Keels In Production Yachts

[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/...1_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...hp?gal=1&pic=8
http://www.balticyachts.fi/Yachts/56...p?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...681811,00.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 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

[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!

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]

Originally Posted by Lorsail

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.

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]

Originally Posted by Lorsail

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?