Small trimarans under 20'

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That's interesting but depending on what you're testing rc models can be very beneficial according to Greg Ketterman, Dr. Sam Bradfield, Yves Parlier, Hugh Welbourn, the CBTF guys, Paul Larsen(SailRocket) and many others.
But the subject I brought up about flying the main hull early by using a wand controlled foil on the daggerboard and a trailing rudder foil has nothing to do with models-it is an absolutely proven technology used in a different way on all kinds of boats-it is not based just on model results it is based on full size proof of how a bi-foiler system works and on full size proof of how wand controlled foils work-not speculation-FACT.

 

But those guys are using / used very sophisticated tanks, highly accurate calibrated measuring equipment and incrediably detailed models made to high accuracies and can be repeated over and over again to rule out statistical inaccuracies. Without that repeatibility then testing such as that taken place with the Fire Arrow is almost meaningless.

Sorry but unless that model is built to full size and repeatibly tested then we should tend toward ignoring the results.

Yes foils with or without wands may bring about speed increases but at what cost to our 20 ft Tri ? reliability and useability perhaps, difficulties off the water perhaps when launching or trailering. Will they bring benefits such as smaller sail areas. They are a conundrum and perhaps need to be specifically put into a Thread all of their own to stop the subject running into the usual foil burn out.

 

I would like to see a real person-carrying tri with Doug's special foil system. Until then, I think the mini hydroptere boats like the broomstick, hydroptere proto and ( kotuku?) are the fastest around, especially since they are tried and true. Sizzors is not bad either, but I suspect randy and his skill has the most to do with it. If you want rugged reliable speed, like banque populaire V, I would dispense with all the foils you can and just keep rudders and foil assist daggerboards.

 

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Absolutely false! Your statement above is inaccurate and simply does not represent the facts.
1) I worked one summer with Doctor Sam model testing for his 40' SKAT. He told me that he considered the RC model that I designed and built and sold him for testing an excellent way to test a foil systems placement, balance, altitude control, pitch control, rig placement, weight and weight placement. RC models are not suitable to test the actual foil section but he found almost direct correlation between the model foil area and the full size foil area.
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2) When I was building RC models, I worked with Bill Burns who did numerous RC models to test CBTF.
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3) There is a paper somewhere under "Sailboats" that Greg Ketterman sent me with pictures of the RC model he built to test his foil arrangement and altitude control system, pitch control,weight placement and rig ideas.
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4)On the DSS website and in other places is the story of the invention of DSS-one of the first things done was to test on an RC One Meter and on other RC boats.
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5) Paul Larsen has done a great deal of RC model testing, see below, and he is in the process of working on another test model for his ocean going version of SailRocket.

Pictures,L to R, 1) Alain Thebault with his RC model of Hydroptere, 2) Yves Parlier's RC model of his planng hull cat, 3) Dr. Bradfields RC test model using a platform designed and built by me. Used to test foil/rig placement for the 40' SKAT,4) Paul Larsen with Sail Rocket RC test model:

 

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Foils have a long history on racing tris-they not only increase speed but improve the ride and allow the boat to be pushed much harder with more safety than boats without foils. Many tris above 20' now use ama foils as standard. Perspective boats is developing a 19' tri(Exocet 19, see below) using Uptip foils on the amas. Foils are a proven benefit when properly designed.
It's about time that the benefits of foil assist are used on smaller tri's-it would benefit a lot of people.
The foil system I was talking about in post 272(see below), is a system that can improve speed and handling in light and heavy air while at the same time making the boat more secure in pitch.
It's ludicrous to try to ban the discussion of foils as part of a thread I started about 20' and under tri's-there are proven benefits that can be used now-and the result would be a faster, easier to sail boat with a better ride and as much comfort as the designer wants to include. Foils have proven themselves and, like it or not, more and more boats-trimarans included-will be using foils to enhance peoples experience on the water in ways that haven't been possible until recently.
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POST 272:

Pictures,L to R, 1)Martin Fischers foil assisted Jessica Rabitt-the ama foils are designed to lift 80% of the weight. This kind of system would work well on 20 and under tri's., 2) The Exocet 19 being built in France uses an UptiP foil and rudder T-foil on each ama:

 

Abandon ship! This thread has become another soap box for Doug Lord. Kidding of course Doug, but I was more interested in the feedback rcnesneg was receiving for his design than hearing you defend yourself. We are all well aware of the other items you have posted. You've made us well aware in other threads that you worked with Dr. Bradfield, which must have been fascinating. Is it possible to bring the thread back to rcnesneg's boat? If there are more than three or three posters on this thread, he may actually get his design to a point that it gets built! Is that the point of this thread or were you going for something more conceptual?

 

I would certainly agree with you Doug that foils will have a place in the future of small Trimarans, but we have to bring reality into the equation and at this point of time, it would almost be pointless to incur the additional cost in both structural and financial resorces to warrant the extra speed foils will bring to sailing a small Tri.

 

Can you give us examples of the system in use anywhere else? Preferably more video footage.

 

Happy Feet

As far as I know there isn't trimaran using the system I suggested for the main hull of a trimaran except my test model-however, there are numerous boats that uses wands as altitude control singly or in pairs on cats.
There is one catamaran the uses a single wand controlled main foil and a single trailing rudder T-foil. It's called "Happy Feet" and their system was designed so that the mainfoil and rudder foil were mounted in such a ways that they could side sideways. The foil worked in basically the same way as mine when it was centered: 1) it maintained an angle of heel, 2) it would add downforce if required.In other words the foils did pretty much the same thing for Happy Feet as they would do for a tri-only on the tri they would work much better because of the beam of the boat. But the principle of using the foils to hold an angle of heel was demonstrated on this boat. The original "Happy Feet" design was supposed to allow the whole boat to foil when the foils were slid to leeward.

Pictures- the foils were mounted in the center pod which could slide sideways
Heres a video:
https://www.youtube.com/watch?v=bOCnQIci5G0

 

Another Happy Feet video where you can see the pod moved to leeward and clearly see the foils and wand:
https://www.youtube.com/watch?v=ZggxS6ZrVOw

 

Hmm. Seems to have worked very well there. Why don't you do the same thing, use a cat with a pod under the middle, but maybe with a single rig instead of biplane?

 

Because the tri works better.

 

Why? Catamaran obviously worked better for them.

 

why?

Because the trimaran has more beam between the main wand controlled foil and the lee ama which increases the effect of downforce as well as as increasing the power and potential speed of the boat. The use of this system on a trimaran designed for it allows low wind speed takeoff of the main hull(as it would flying the windward hull of the cat) but on the square or oversquare tri the benefits are exaggerated compared to a relatively narrow cat.
Unfortunately, we don't know the real benefits to the cat as might be indicated by race results-I've not been able to find anything. But as a proof of concept for using a bi-foil arrangement on a tri it is excellent because of comments made on the videos about the foils "holding an angle of heel" which a bi-foiler arrangement does on a tri but with greater benefits. This system works 100% perfectly on the Fire Arrow-or you wouldn't see video of the main hull flying since the wind was not strong enough that day to fly the main hull w/o foil assist.

click-

 

Why not ditch the center hull and have an oversquare catamaran?