why canting keel?

[freemanjunelee]

Hi folks,

I'm still wondering about the canting keel system.
It is said that the canting keel tremendously improve the boat performance.
I think this would be truth to a big boat like super maxi. but I'm not sure that this is truth to a small boat like mini open 650.

I need any information about the canting keel system, advantage, disadvantage or limitations.

Cheers.

FJL

[astevo]

how about instead of starting a new thread, you read any one of the ones already existing,

[Raggi_Thor]

CBTF(Canting Ballast Twin Foil)
for example, long discussion....

[usa2]

maybe he just wants a straight out answer rather than having to read through those threads.

[Raggi_Thor]

OK, but there are many opinions on this, here are my thoughts:

Canting keels in small boats let you tack faster than with water ballast.
Water ballast is cheaper than lead and also easier to build and operate.
Canting keels has the ballast lower than the water tanks so the boat is safer.

Take a look at Backman 21 for instance, there is a simple rope mechanisme, no hydraulics etc. www.backmanboats.com

For really small boats most of the stability is due to the crew and the ballast is there only to right the boat from extreme heeling angles or knockdowns. See our Backman 18 :-) http://www.mboats.no/B18/backman_18.htm
There is no reason to put a canting keel on a very small boat when the ballast is only 100kg or less.

There is a discussion on "should racing boats use stored energy or pure human power to move the ballast?". If no stored energi is to be used I think it's quicker to cant the keel than to pump water from side to side. Of course you can open the valves before you tack and let the water flow down to the lee side. You can also have water or other inside ballast moved mechanically, probably faster than by pumping.

So to sum up:
If the crew weigh (much) more than the ballast there is no need to move the ballast.
Canting keels put the ballast lower than water inside, so the boat is safer.
The same rightning moment (for a given heeling angle) can be otained cheaper with water (or other inside, moving) ballast than with a canting keel, but this moment vanish when you may need it most.

[Raggi_Thor]

forgot to mention that you can get rid of the water when you dont need it (in light conditions and on a trailer).

I am afraid we are starting a new discussion here :-)

This has been done before as well but: the biggest disadvantage for a canting keel when used on a boat expecting good upwind performance is the requirement for some form of extra lateral resitance as the keel cants.
There are numerous systems with varying degrees of real world experience:
1) single retractable daggerboard - some of these systems allow for a "gybing " daggerboard or use trim tabs on the board.It can be mounted in front of or behind the canting keel;sometimes called "TMF" (triple moving foil)-used a lot
2) twin asymetrical daggerboards- these are generaly mounted to the boat with a preset angle of incidence.-used alot especilly on Open 60 raceboats and similar smaller designs.
3)CBTF-this is patented system that uses twin fore and aft foils for turning and lateral resistance with low wetted surface keel strut.Uses "collective" control of the twin foils. Works best with high cant angles-50°-55°.(Used alot especially on race boats.)
4) Fixed wings- this system uses wings similar to the wings on IACC boats to generate lateral resistance on a canting keel. Used mainly in Australia so far on successful race boats like Atomic.Patent applied for..
5) KFOIL-patented system utilizing retractable wings; foils retract into the keelbulb. untested as yet.
I think a canting keel can be effective on any size boat where you currently find fixed keels-from 12' on up.

[usa2]

a canting keel will make your boat faster in any condition because it allows you to carry the rig more upright which results in more driving force. They are most effective on offshore boats that dont run the risk of getting into close tacking duels. The two 98' supermaxis in AUS are an example of canting keel versus fixed keel/waterballast. Konica Minolta is faster in lighter air and inshore than Skandia, who is exceptionally fast but can be outdueled inshore.

[John Perry]

Originally Posted by Lorsail

4) Fixed wings- this system uses wings similar to the wings on IACC boats to generate lateral resistance on a canting keel. Used mainly in Australia so far on successful race boats like Atomic.Patent applied for..

What!! that can't have a valid patent. Apart from anything else I did a detailed poster with drawings and description of such a system which was displayed throughout the London Boat Show on the AYRS stand many years ago, I still have it somewhere. After that I read in a magazine that Ed Dubois had applied for a patent for something that sounded similar so I rang him up just to let him know that he was wasting money and he told me that someone else had just called him to say the same thing.

So many patent applications, so few that are valid. Almost everything has been thought about from Victorian times onwards, but there is still progress to be made by actually making some of the ideas work on the water.

John

John, the information I gave was by no means enough to determine the validity or invalidity of any patent Andy Dovell has filed! You can't patent an idea only the specific way it is implemented.
That being said I have no idea whether Andy has received any patent protection yet. But his wings do work-apparently very well-upwind and downwind and could be an excellent solution for canting keel systems for owners that want a fast system with the minimum impact on the inside of a raceboat in terms of taking up space.

[usa2]

how is CBTF a specific way of implementing a fore and aft rudder configuration with a canting keel? Thats more of an idea rather than a specific way.

You need to read Alberto Calderons(with Bill Burns and Matt Brown) patents to understand ,even remotely, what CBTFco has protected. Thats a thing about patents: many peope will leap to conclusions they really don't have a clue about regarding what is protected in certain patents. People that make important decisions based on that kind of information can make serious mistakes.
There is no way that someone not skilled in patent law can tell you with any degree of certainty what is covered or NOT covered in a certain patent. When a technology such as CBTF is protected by more than one patent the level of coverage is even murkier for the average person.
The best way to find out how good any patent is is to violate it; the problem with that is if you lose.

[usa2]

so basically they are protecting something that may be a cnoncpet but it could be cleverly worded so it looks like its protecting something that is a specific implentation. damn lawyers.

Don't be jealous; CBTF has a proven race record-see the other thread.

[usa2]

oh i know that, im not criticizing the technology or how it performs on its race boats, im criticizing the move to patent it. It really is a concept because the canting keel was around beforehand and so was fore and aft rudders. of course the wording may suggest otherwise and probably on a technicality is what makes the patent stand, but thats okay. Waterballast is a concept, but no one has patented it, even though there are "specific ways of implementing it".