Sport sailing in multihulls: to fly or not to fly…

To fly, of course!

by Malcolm Gefter

Malcolm is a member of the New York YC, a racing enthusiast and also one of the first owners of the TF10 trimaran, the famous foiling tri built by DNA (which we tested in Multihulls World 160).

My opinion about foiling is quite simple : if you are NOT foiling while sailing, you are not sailing in the modern world at the highest level. it could be argued that the art and science of sailing requires one to attempt to get from point A to Point B as fast as possible. Aside from tactical considerations (which are important ) such as seeking the best wind and current conditions to get to the goal, speed, is by far the most important. Foiling is not a discontinuous feature of sailing mechanics, it is on a progression line of a body of physical features that strive to reduce weight, reduce drag, and increase righting moment for a given platform, in order to increase speed. The continuum of drag reduction  in multihull sailing goes from flying a hull, to flying a hull and skimming with the hull in the water, to lifting the leeward hull out of the water , and "sailing" on the foil. Righting moment increase with less overall weight is moving the mass outboard from the CG which justifies multihull sailing as an improvement on RM relative to a monohull. In a foiling multihull, one can also increase RM by applying downforce to the windward rudder So foiling is just a more efficient way of sailing then not foiling. The fact that the boat must be sailed level in both dimensions, and the speed increases dramatically, imposes some changes to the details of sailing, but the principles are the same. Speed increasing also requires more aerodynamic considerations to speed in addition to hydrodynamics.

Speed also imposes new challenges such as cavitation and ventilation of foils, but these are details, and the details required to improve performance is a REQUIREMENT of sailors to embrace when foiling.-Going back to non-foiling while sailing is like going back to full keels and wooden boats. There will always be a place for the sentimentalists who prefer the "comfort" of the familiar pre-foiling days. they will shrink to the minority. 

A fast ‘Archimedean’ trimaran rather than a foiler

Herve’s playground is the north coast of Brittany, as far as Cherbourg, with the Channel Islands and thousands of rocks, and the south coasts of England and Ireland. He is a racer (skipper of Rush Royale Perros-Guirec in the Tour de France à la voile), has had the opportunity to sail regularly over these last few years with an Echo 36'V2 (one of the latest Dick Newick designs), and previously had just a few occasional experiences in cruising trimarans: Telstar 26, VAL 38 Elle… He loved it!

I took part in the submersible/insubmersible float debates (André Allègre, Derek Kelsall…) before Eric Tabarly's foiling trimaran Paul Ricard made another controversy public in 1979: foils or no foils? My point of view as a sailor is to go ...