Squidly-Diddly: hull showing default hatch openings, and deck-bolts
the openings have rims, for strength and splash-defection.
the hatches could be simple covers with skirts, and not hingled but "loose" and thus able to be dogged-down with simple foolproof methods.
to open the hatches, the covers would be un-dogged and then slide towards the middle and stored between the cross beams, just under the deck.
the grey area on the side of the hull is vertical and flat, and would thus mate with other hulls flat section when trailing. also, a flat section might help simplify mounting of equip inside the hull.