These foils allow automatic altitude control of the ama with no moving parts.

Trimaran ama shapes. This trimaran is the perfect preppers unsinkable escape vehicle. Most trimarans use symmetrical hulls port starboard as does the Cross but contrary to catamarans where symmetry makes good sense trimaran amas are not both in the water at the same time and the one that is significantly immersed is typically always to leeward so it presents an interesting opportunity to be asymmetrical IF indeed there is seen to be any advantage. The high buoyancy planing geometry is highly resistant to burying the bow at any speed.

There is a video of 2 of these small trimarans sailing along. Construction continued until 1981 with some minor modifications to the main design and then stopped. His amas were designedprimarily just to aid static stability but as you can see in the picture could help a bit at other times.

Trimaran Performance vs Hull Form. The ama shapes especially on the smooth hulled variation borrow other design cues from the modern performance dedicated French designs of VPLP as well as the very cool work of Nigel Irens. MARPLES 35 CC35A TRIMARAN.

Amas are the outer hulls of a trimaran sometimes referred to as outriggers or the smaller hull of a proa. While the first 2 AB are primarily potential designs for a narrow trimaran amas the last 4 CDEF could work within limits for either the main hull or ama though I do not personally recommend shape D for the reasons given below. Typically a trimaran hull is the principal displacement supporter as well as the main accommodation area.

The transoms are nudged in the direction of a triangular shape while retaining some of the typical beach cat flat-topped U-form feeling. Inefficient underwater and keel shape often with either a fixed keel or no keel at all. Nevertheless every trimaran will occasionally bury the ama bow.

So you pick a hull shape that might be a compromise at certain speeds but will work ok at others. The line has been designed and built by Tony Smith with the initial design created in early 1970s. Unladen weight is approx 80kg for the 16ft Osprey double outrigger.