The following extract concerns one of the first "Exoplanes" and comes from "Faster! Faster! - The Quest for Sailing Speed" by David Pelly, (ISBN 0688023894) pp 168,170. The B&W image is by Guy Gurney and appears in the David Pelly book.
Didier Costes...A quiet, charming nuclear physicist, he has spent a number of years playing around with a collection of pieces of bent aluminium which come together annually to form the extraordinary "Exoplane". This is the kind of craft which attracts a small crowd of puzzled looking people who don't quite like to admit that they are trying to work out which direction it sails in. They will be wrong in either case because "Exoplane" is a symmetrical proa which reverses direction rather than tacking.
The boat itself, with
its curved, reversible hydrofoils is intriguing enough but the real interest lies in the
rig, which represents at attempt to completely eliminate heeling force. The sail is
set something like an umbrella, set to leeward of the boat on the end o f a spar at an
angle of something like 45 degrees to the horizontal so the heel is exactly balanced by
lift. It is a very impractical craft which spends 95 per cent of the time on the
beach being repaired but just occasionally Costes gets everything right for a few minutes
and goes skipping away at an impressive rate - usually in the wrong direction. Like a
lot of the 'wild' Portland competitors, "Exoplane" is a failure as a boat but
serves to demonstrate a very important idea: that of the no-heel rig.