I want to build my own fiberglass riverboat. I have some experience fiberglassing and love building stuff, regardless if its cheaper. My thoughts are 21'x48"x18". I am kicking around the idea of a self bailing deck but I dont know, that would raise the deck quite a bit. I am thinking of making it a partial tunnel hull(3-4" deep, 3ft long). 4-5ft front deck, 3ft rear deck.