Originally Posted by boatman61
Rather than attack the bottom I'd go for the cockpit floor.. just leave a couple or 3 inches all round to sit then epoxy and screw the new floor on.. run timber raisers/braces at the bulkheads..
Glass in either aluminum
plate or encapsulated plywood
around the lip of the cut out floor, and through bolt it by getting a small person or a larger child to hold the nut while you bolt it snug from above. This will tie the boat and the "lid" together. If you are worried, reinforce from below if you can to a tabbed in bulkhead.
You may have to glass a better lip around the cut out unless you are very
fastidious with your sawing.
Of course, another option, one which is more expensive but less destructive and labour-intensive, is to cut a square for an access hatch
in the floor of this type: