So, I searched everywhere for something, anything on building an engine hatch on an old jet boat but only found like 2 things. There is really not that much info on size, shape, design, material or weight. I figured I would post some stuff about how I ended up doing it. I do not know if it's right way or even if there is a "right" way, but at least it'll give someone some ideas if needed. I wanted people to be able to walk across it so I went with mostly 2x4 framing with the exception of the starboard and port outside most framing, which i used 3/4 in plywood. The intake and carb stick up quite far from the compartment so I designed a cowl induction type scoop that is actually a second piece. After framing, I wrapped the hatch with polar fleece and applied poly resin to get the shape of the hatch. I stapled the fleece where there was frame to staple to, to ensure a good bond. After that I applied 2 layers of 2 oz chop mat and then finalized it with 1708 bi-axial. I haven't finished it yet and I will update if anyone is interested in the finished product. I know I'm leaving some steps out, so feel free to ask any questions.