the hatch to gain entry into the forward battery room in the middle of the officers room at around frame number 70 if you have a construction plan handy. there was a hatch above this room in the pressure hull which was bolted shut was used to lower in a new battery or remove a defective one. The pressure hull cover was rectangular in shape and since it was not used often it was bolted shut with alot of nuts,the studs were part of the pressure hull. The floorboard hatch near the captains room and the control room hatch was for the ammo magizine.