Before I order the hatches, I wanted to try out which size I need. Firstly, I made a hole in the smallest size I was considering.
I could fit through it, but I’d better go for a bigger one.
That way I can get through the bulkhead easily.
Another detail: I made rails on the bunk-sides. They keep the mattresses in place. The holes are for attaching lee clothes (piece of cloth or net that is fitted between bunk side and roof, to stop me rolling out of bed when the boat is heeling).