Thanks Charles and everyone else for the useful advice.

The remit for my design is for a car toppable cat, that when packed up it can be carried down to the water in one go. I also want all assemblies to clamp together without the use of any bolts. (There was a cat called an ALLEY cat that had a similar design, however there were too many bolts involved, making assembly a little too long winded.)

I am also keen to use windsurfer style planing hulls. Apart from the wish to experiment with such a hull shape, by using flatish hulls, I can pack up the whole assembly so the rigging, rudder etc sandwiches between the two hulls for easy stowage and transport.

The main design problem I am experiencing is in developing a light weight method of raising the trampoline and cross beams to give enough clearance between water and sailor. (This cat will only be used in an estuary so not too much clearance should be required.)

Anyway, I'm having great fun thinking through the individual problems.

By the way I have already built the first hull using a plywood underbelly and Styrofoam SPX that I have shaped. Once happy with the hull shapes I will lay them up with some fibreglass.

And yes, I will be wearing a crash helmet, whistle, flares, radio on the initial test