A power trimaran is kind of an odd looking bird when you first
look at one. Long skinny hull with very short amas. We have gotten
used to seeing amas that are more than half as long as the main
hull in sailing vessels. But of course the power tri needs a much
smaller righting moment since there is no sail to rotate the boat
around it's axis.They are much more stable that the equivalent monohull
of course, and most of the recent long range power boat records
have been set by trimarans of this type. An unrefueled crossing
of the pacific was done several years ago with a pair of slightly
modified 9.9 yamaha engines. and the UK navy has had a development
program in place for some years and has begun to acquire a few.
Here is a picture of one. Built in australia, I believe.
A beautiful Nigel Irens design - 21 meters, built way back in 1988
And an Irens 35 meter went round the world in 1998.