There was a fiberglass
Hobie 11, that would sink with more than 130# of crew. It is just a question of displacement
; if you want to float something that weighs 130#, you need to build something that takes the same amount of room as 131# of water!
Picture a long piece of foam with a triangular cross section with the ends tapering to a point over a two foot length. They look like a very tall three-sided pyramid. If you l;ay them head
to toe, they will together displace the same amount of water
as a two foot length of untapered hull
. The total displacement
of your two hulls is now pretty easy to calculate, and the result would be a useable approximation of a hobie hull
. You do the math!