Sounds feasible, and working with wood-such an easily modifiable material-almost anything can be accomplished.

One thing you might at least think about is whether you'd like to move the hatch such that it had to be installed from the outside/bottom of the hull. Of course it would require creating a sealing lip/ring for it to press against, and could be designed such that the outer side of the hatch was flush with the hull.  The reason I'd give this some thought is that the water pressure (granted, 6" of depth or so is minimal pressure) would be tending to seal the hatch against the gasket, much less relaince on fastener hold-down pressure to create the seal.  With a hatch installed from the inside, I'd fear anything less than a good solid sealing surface, strong, flat hatch that never warped, good gasket, firm fastener pressure, etc. might lead to leakage.

You'll obviously not be pulling the motor well waterborne withe either design, so an exterior hatch could work, but you'd also need ot consider a little more fussing about how you'd access it to install - sitting on trailer, rolling boat on its side, whatever.

   Bubblehead,

Great food for thought.  If I could install from the top side it may be easier,  but I appreciate your point regarding the seal.

Thanks