No Gelcoat Needed. Ceramic-Based Epoxy?

I don't know if my input will be of any help but here goes. As I understand it the resin in fiberglas is not really water proof. A barrier coat is applied to prevent water intrusion and the scourge of blisters (common on older boats). Below the water line, nearly all sail boats that remain for long periods in water especially warm salt water are painted with an ablative which helps to prevent barnacles etc. from adhering . Power boats require a harder version so as to prevent the paint wearing off at higher speeds. The ablative on my sail boat, a high end Petite product , lasted 5 years under tropical conditions and was still in good shape at our last paint. Above the water line the fiberglas is coated with gel coat, a protection from the uv rays. It couldn't be easer to maintain. A weekly washing, a wax job once in a while to slow oxidation and after 10 years it looks almost new. Scratches and dents caused by arguments with docks can be addressed by professionals with good results. Don't write off this proven technology. Much much harder to keep up are varnished wood, teak decks and surprisingly stainless steel.

 

Because your toilet bowl is made of ceramic with a fired glaze over it. If you want the same, you can make a ceramic boat with a fired glaze finish. It will be very heavy and rather brittle.