CBTF(Canting Ballast Twin Foil)

I'm interested in hearing as many opinions as possible about this new technology. Seems like a real breakthru in monohull speed....

[SailDesign]

Doug,
Since your company (microSAIL) has an "ongoing" relationship with DynaShip (the "Originators" of this technology), why don't you ask them about it? They have far more experience than we do...

If you've lost the link, here it is:
http://www.microsail.com/innovate.html

Steve "no patience today..."

Thanks for the suggestion Steve. I'm curious what opinion others have of the technology......

[Stephen Ditmore]

I think the marketing is a litte gimicky, though I suppose they're just trying to recoup their investment and make a little like everyone else. I don't see any advantage over the canting keel / bilgeboard combination now used on many open class singlehanders, and I see what could be a disadvantage. When surfing downwind I'm more comfortable knowing the center of lateral area is well aft. While I'm sure the realtively narrow hulls of the DynaYacht designs make them directionally stable most of the time, I'm thinking you don't see canards on boats that surf downwind in the roaring 40s because there's a high speed trip, broach, & crash potential, or at least a likelihood of a serious canard failure. Then there are the issues the rest of us deal with, like groundings and catching weeds. I give the designers credit for being early into canting keels, and for working through the control problems experienced by Blackaller in Perth (A.C. 1987) and the Swiss in America's Cup 2000. The canting keels are catching on, but I remain a skeptic concerning canards, especially when the result is a center of lateral area (rudders included) forward of the center of the hull's waterplane (the LCF).

If they want to prove me wrong they should design an Open 60.

And so they make a monohull faster; who cares, it's still a lead sled no matter what. Wild Goats is not competitive with a 60' tri, and the keel takes up some space inside. I also know designers who prefer water ballast because you can dump it when it's not needed.

I love monos, because they are fun to sail. But they are not fast, and reducing some of the mono's benefits (lots of similar boats to race against, reliable fast tacking, close safe racing without major problems in low-speed collisions, ease of slipping etc) while trying to turn a leadmine into something fast seems to me a bit like making the world's biggest bonsai tree, or the fastest motorhome.

If you want fast, don't sail a ballasted mono. Sources as diverse as racing against the Open 60s and the French national handicaps and British racing experience of Mini 6.5s indicate, btw, that they are not rocket-ships around a closed course considering the size of the rigs, so not even water ballast makes a major difference in that respect.

Hamilton Island results show that Another Duchess (Bob Oatley's other boat, Davo 60 (-ish) now fitted with CBTF, was often only aboout 3 min faster than her conventionally-keeled sistership Aftershock. I don;t know whether Duchess had other alterations done, though - can anyone fill me in?

I do like the foils on Goats, from an aesthetic viewpoint when they are out of the boat; high aspect and elegant.

Well, you did ask for opinions

You're so right: I did ask for opinions and that was one; thanks....

[nico]

I dont think Another Duchess is CBTF. Just a trim tab on the keel.
See last Seahorse.

Nico is 100% right; Another Duchess is a "standard" fixed keel though the keel has a trim tab and the fin/rudder /ballast package was recently optimized by Reichel-Pugh....

[Stephen Ditmore]

In the new (October 2003) Sailing World there's an article on the new Volvo 70 class by Perotti and Van Gorkom that includes drawings of a CBTF design with dual rudders aft, making it a Canting Ballast Triple Foil I suppose. I'd regard a Volvo 70 racing 'round the world a test as valid as an Open 60. To calculate the design's center of lateral area I'd count both aft rudders (though only one aft rudder is visible in the profile drawing). Because the lateral area is effectively farther aft I'm more hopeful that this design might behave predictably. Ability to rake the mast forward downwind might also help.

Phil Bolger has designed several (inexpensive plywood) boats steered with canards including one for himself with a daggarboard aft. He found that increasing the size of the daggarboard improved the boat's manners considerably. During the Louis Vuitton Cup in 2000 I wrote to Peter Van Oossanen of the Swiss design team proposing they fly Bolger out and give him a shot at correcting their control problems. Van Oossanen responded, assuring me their concept was theoretically proven. Yes, but...

Let me add that I'm a fan of Doug's remote control models, some of which are based on Whitbred 60s (predicessor of the Volvo 70). Like Bolger, Doug has experimented with things at a reduced scale and cost, and I don't doubt has learned much. I'm interested in your thoughts, Doug, but I'm sticking with my rule of thumb, CLR should be aft of LCF, unless/until I'm proven wrong.

Cheers,
Stephen

P.S. - I do find it odd, Doug, that in reading about CBTF on your web site the name Alberto Calderon seems to have dropped away when he was one of the primary people involved in the development of this concept, some might say THE inventor or the driving force. Also, there was a well known sailor who drowned in San Francisco Bay racing one of the prototypes. It would be classy to stop the breathless promotion long enough to memorialize him.

Stephen, on my rc model website I don't mention ANY of the original designers that have pioneered CBTF but I do have a link to the CBTF,inc site that does . Your comment is the first time I've heard of anyone dying while testing a CBTF prototype.I've written Bill Burns to get the story...When preparing to introduce a new technology to a skeptical audience it is important to provide the most information possible. "Breathless promotion" may befit the description of WHO is doing our rc model CBTF design but as to CBTF itself we've tried to specifically discuss what it is and how it works--which when you realize what it's potential is could possibly leave you breathless.....

UPDATE: Stephen, I'm aware that there is a lot of BS circulating about CBTF but I am dismayed that anyone would pass along a rumor of this magnitude with so little to go on!
I just talked to Bruce at CBTF,Inc. and there has NEVER been a death associated with racing any CBTF boat!
The only possible connection that you could be referring to is the tragic death of Larry Kline in San Francisco Bay sailing Green Hornet. Green Hornet was a heavily modified Hobie 33 owned by Alberto Calderon and had a TANDEM KEEL CONFIGURATION put on the boat for an America's Cup campaign--NOT CBTF!!!!
The boat was outfitted with racks ; a weld failed and Mr. Kline was dumped into San Francisco Bay and died of a heart attack. Tragic, sad, but in no way -by any stretch of the imagination- related to CBTF......

[Paul B]

The person who died was Larry Klein. He owned J World in SD at the time.

The boat in question was a modified Hobie 33 with CBTF and hiking racks (Green Hornet). A weld on those racks broke and the crew was dumped into SF Bay. Klein apparently had a heart attack and died.

The problem did not have anything to do with the CBTF system on the boat.

CBTF has some promising ideas, but also some problems. I think it is still on the steep part of the development curve. It is nowhere near as great as some people try to pump it, and nowhere near as dangerous as some others try to paint it.

EDIT: I just posted this and apparently Lorsail posted the exact same info while I was typing. I would disagree about the Green Hornet not being a CBTF boat. Follow the link to see the modified Hobie 33 (with transom extension to 38 feet) Green Hornet with CBTF.

http://www.dynayacht.com/designs/pro...ypes_index.htm

Paul, just a clarification: at the time of Larry Klines death Green Hornet had racks and a tandem keel.
After that accident the boat was modified to be a CBTF prototype.....

[Stephen Ditmore]

I never said or implied that CBTF caused Larry Klein's death. Unfortunately, however, his death is neither a rumor nor BS, and is part of the history of CBTF development.

Doug, your web site contains the statement:

CBTF = Canting Ballast Twin Foil technology was invented some time ago
and patented by Veteran America's Cup deisgners Matt Brown and Bill
Burns of Dyna Yacht Incorporated.

US Patent #5622130 lists the following inventors:

Calderon, Alberto A.; La Jolla, CA
Robinson, Charles W.; Santa Fe, NM
Burns, III, William F.; San Diego, CA
Brown, Matthew B.; San Diego, CA

in that order.

US Patent #5163377 lists the following inventors:

Calderon, Albert A.; La Jolla, CA
Robinson, Charles W.; Santa Fe, NM
Brown, Matthew B.; San Diego, CA

in that order.

I checked the DynaYacht web site and found no mention of Calderon, Robinson, or Klein. I maintain that it would be classy to mention these contributors by name somewhere in the multiple web pages devoted to the this approach to underwater appendages, and to include a link to a bio for each. This is not an attack on the technology; it's a suggestion for your web sites. My reservation about canards was spelled out separately and in detail in response to your request for opinions, and I gave you credit where credit is due. I request that you be fair to me in characterizing what I've said. If you have a problem with something I've posted please quote it specifically.

Stephen

It is simply NOT TRUE that Larry Klines death is "part of the history of CBTF development"
That is a false statement and should be retracted-please.....

[Stephen Ditmore]

I'm not convinced it's entirely false. Green Hornet was modified from its production Hobie 33 configuration and I have to suppose was being used by Alberto Calderon and others associated with CBTF development to test steering geometry variations. It may not have had a canting keel at the time of Klein's death, but people were aware even before that tragic event that Green Hornet was part of the Calderon team's development effort.

Dave Hubbard employed a canting keel on Red Herring about 20 years ago. The more recent innovation related to CBTF was the canard/rudder combination pioneered by Calderon on Tom Blackallers's USA in the 1987 America's Cup. I therefore see all of Calderon's activities since 1987 aimed at refining this concept as part of the history of CBTF development, even if combining a canard with a canting keel came later (first prototyped using a Soling hull I think, and Green Hornet subsequently).

You seem to be suggesting, Doug, that I cast the net too far. Perhaps. I don't know if Burns & Brown knew Larry Klein or were associated with Green Hornet at the time of his death. I'd like to see enough CBTF boats built for the concept to be given a fair shake, and don't mean to be casting aspirtions beyond my reasons for favoring a conservative approach to directional stability/control. I'm just telling you that in the mind of this east coast former marine industry professional Klein is associated with CBTF, and I doubt I'm unique in that impression.

I fully accept that it was the failure of the rack and other circumstances not associated with CBTF that led to Klein's death. I just want to see Calderon and perhaps others acknowleged for their contributions, and I think including Klein would be a classy and graceful way of dealing with the perception that I believe is out there, fair or not.