TMF versus CBTF

[usa2]

what are peoples thoughts on the Triple Moving Foil system Nicorette uses versus the conventional CBTF or the canting keel/daggerboard systems? Nicorette seemed to be performing exceptionally well for a 90 footer against the 98' Skandia before Skandia had her crisis and Nicorette slowed down to stay in one piece.

I've heard some comments about TMF but never a clear cut explanation. Can you explain it?
From what I gather they move the rudder canting keel and the forward "cannard"(small rotation) .
So does CBTF except that the twin foils are linked together to provide superb manouverability as well as to allow "collective" use upwind.
Seems to me that a boat with a non rotating canard or even a canard with limited rotation is going to be at a disadvantage compared to a CBTF boat.

[usa2]

Triple Moving Foil consists of a deep aft rudder, the canting keel, and a forward canard that has a trim tab on the trailing edge. This forward canard is semi-retractable so unlike CBTF boats, off the wind when it is not needed it is pretty much out of the way. It looks like a good idea that gives you both the ability to cancel leeway with the trim tab, and the flexibility to pull the forward canard out of the water when not needed. The CBTF boats have their forward canards designed with the possibility of collision in mind. This eliminates that problem to a certain degree.

[usa2]

apparently Skandia also had this arrangement I just found out....

Are you sure about the flap?

[usa2]

yes, it was an article on scuttlebutt europe that had an interview and staed that skandia had a retractable daggerboard with a trimtab that was designed so it would make the board seem asymmetric, therefore being more effective than a symmetrical forward canard.

The trim tab may be one of the only ways they can get around the CBTF patent....
And by the way I think it would be possible to retract a CBTF forward foil using the VARA rudder system but I doubt you'd gain anything since part of the benefit of a CBTF installation is better downwind tracking (according to the CBTF guys) as well as the fact that the correct placement of the CBTF foils reduces wavemaking resistance-something that does not occur with other systems.(see www.cbtfco.com under "technical" )

[usa2]

you are probably right about trim tab being a way to get around the CBTF paptent. However, it seems rather efficient, and off the wind a foil that is farther forward of amidships tends to sometimes create a lot of drag. In CBTF boats this drag helps suck the bow wave down. In boats such as Nicorette and Skandia, instead of sucking the bow wave down, they just will ride up over their bow wave. And the better downwind tracking is questionable....

So the forward foil on a CBTF boat causes the boat to not plane because it "sucks the bow wave down" while Nicorrette and Skandia ride up over their bow wave??!! I would guess you're saying that theory applies to the Schock 40, Pyewacket and Morning Glory among others?
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What about the picture on the right on the first page of this website:
http://www.santanasailboats.com/boat...0/schock40.htm

[usa2]

no. I didnt elaborate on it. CBTF boats will plane. They will just plane later than a similar TMF boat. Also, if you are in surfing conditions off the wind, that forward foil is going to act like a brake..Possibly that is a reason the TMF boats were designed for the Sydney to Hobart race, as it is often off the wind in large seas.

Why would Disney and many others spend millions of dollars on ocean racers that had a forward foil that acts like a brake?
Why is it that this incredible design flaw hasn't been brought to the attention of more people in the various forums ,magazines ect? I would think you'd have to be nuts to invest in ocean racing technology with a flaw like that....

[usa2]

A) because its not a huge problem as the CBTF maxis dont even bother to race the Sydney Hobart as they would get killed(Genuine risk might have a chance..) B) How many times have Pyewacket, Morning Glory and/or Genuine Risk been racing in conditions that would cause the forward foil to act like a brake? Not many, because they would have to sailing deep angles in large waves and heavy wind. They dont sail deep angles, and as far as i know, they havent been involved in any races that made it necassary for them to do it.
By the way, both Morning Glory and Pyewacket are for sale....maybe someone realized why Nicorette and Skandia went the way they did on the forward foil. Save money and just as fast.

[Paul B]

Originally Posted by Lorsail

Why would Disney and many others spend millions of dollars on ocean racers that had a forward foil that acts like a brake?
Why is it that this incredible design flaw hasn't been brought to the attention of more people in the various forums ,magazines ect? I would think you'd have to be nuts to invest in ocean racing technology with a flaw like that....

How many Volvo 70s will have this unbeatable technology in the upcoming race? Don't you think that Bruce Farr and the Argentinian Alphabet know at least as much as YOU do about CBTF? Do you think maybe they are getting their info from more reliable sources than websites and magazines?

If you were half the insider as you try to portray yourself as then you would be able to tell us what some of the major design firms have to say about offwind drag on the foil setups available, and why they're making the choices they are.

From your vast experience sailing CBTFers, what's the feeling in the helm when you hook up and surf down a large wave in big wind conditions?

Better yet, have you ever sailed a real CBTFer, or seen one sailing (outside of the toys you play with)?

Yeah "Paul B", you must be right- after all, who would want to spend the big bucks to use such an unproven system on a race boat especially since as "2" points out the system has a built in brake when surfing in offshore conditions! Astute observations such as yours and "2"'s contribute mightily to the greater understanding of this obviously defective technology-too bad I didn't read all this first-live and learn ,I guess........

[usa2]

the Volvo Open 70 designers have been saying that CBTF is not suitable for southern ocean off the wind surfing conditions. Thats why the VO 70s have twin daggerboards instead. For boats like the MZ86's that need to go upwind a lot, and arent as fast as the VO 70s off the wind, its fine for them to have the system. You obviously believe the CBTF technology is something akin to the holy grail...However, it is apparent that there are some flaws.