The fact that no more comments are to the contrary doesn't mean that Frenchie is right.

Also it is not very likely to see much development in foiling craft as these designs often lack speed at the lower spectrum of the windspeed range to be all-out regatta winners.

Of course a good regatta boat has the optimal compromise between light wind speed and strong wind spped, it does not necessarily need to have to be fastest in one of each conditions.

What also strikes me as odd is that 27 knots claims made by displacement boats are branded as inaccurate but that a 32 knot by a cruising tri of similar length called catri is presented as dependable.

Very often people forget that foiling is certainly NOT drag free. Unlike planing , foiling is noticably best near its design speed. Catri's trick to overcome this is to have aiding foiling which is basically a displacement craft of which part of the weight is carried by foils. So the catri is a cross between both technologies. However it would be strange that a say 400 kg's cruising tri of 22 feet would outperform a 170 kg tornado of 20 feet because the displacement of the catri is reduced to say 200 kg's by the foils.

Yes the aided foiling system is expected to improve the performance of a given craft when design well, but that is something else than being all-out faster than all others.

And ofcourse the catri system will never become fully foiled as that would make the whole system unstable. The simplicity of the catri system is dependend on the fact that the (lee)hulls are never lifted away from the watersurface. Only then can the tail foils act like arrow stabilizers and keep adjusting the angle of attack of the main foils to an optimal angle. Without it teh system could go into a run away proces and try to put boat on its tail and be alot slower due to massive drag. With systems like these one always need a good margin between normal operation and full foiling to prevent a freak condition from upsetting this balance and pitching the boat.

So to be able to attain higher top speed the design maximum speed with it's maximum foiled weight (say 75%) needs to be as high as possible. Downside of this is that at lower speeds the amount of foiling is reduced thus reduceing gain there. Set the the speed of maximum foiling to low and the top speed is limited by it's limit to not be lifted free of the surface.

And ofcourse there is the cavitation problem. Use a powerful full foil to achieve noticable foiling at low speed and you are sooner limited in top speed by cavitation. Other way around and in light and medium conditions you will hardly notice any improvement and you'll have made a "go fast only in heavy wether boat" = bad regatta boat.

In this respect foiling is alot more difficult to get it right than planing. But than again foiling can be made to less held back by chop and other not flat surfaces. But the compromise system of the catri is not the best foiling system in this respect. The rave system is better in this, but than again this system is full foiling and thus requires more complex control systems.

Now aftyer this neagtive remarks I would like to say that the catri system is a very neat system that I expect to achive great results with a rather system setup. However this does not immediately translate into being a superiour system likely to be incorporated into many different other designs in the near future.

Please lets not forget that displacement system are still the most simple systems, among the least affected system by seastate with a rather good compromise between low and high wind speed velocities. Especially given their light overall weight of today. This last aspects makes sure that sizeable partions of drag are not the direct result of displacements. A sail rig in a airflow of 30 + knots does indeed created alot of drag too and so do the human bodies hanging from the trapeze. Therefor a large reduction is displacement related drag may only result in a far more limited reduction in overall drag and thus limit the speed improvement. And catri/tornado = 32 knots/23 knots = 40 % speed improvement doesn't seem logical in this respect.

But then again I do not have the full picture of the Catri design yet (sail area, mast hight, aspect ratio, etc)

Wouter