So I was thinking of building a catamaran out of two pieces of PVC pipe, either 6 inch or 8 inch. I don't know how long it would have to be to support me or maybe others. Does anyone know of a buoyancy calculator I could use to try to figure this out? Or maybe I could use ABS plastic. This is very easy to heat and bend. This way I could actually shape it a little more, instead of having it just be round and less controllable.