I have found an answer! (Or at least a partial answer!) I went to a website called pt103.com and found a description of the "day cabin" which includes the following language (emphasis supplied by me):
Crew's dayroom.-Located above fuel tank compartment between watertight bulkheads, with nonwatertight door to forward quarters, and sound-insulating door and hatch in after bulkhead to engine room. This door shall be fitted with double fixed window and provided with gasket seal, and clamp dog from either side, but no lock. A roll-up canvas berth, with portable head-rail, shall be installed each side of cabin, with water repellent covered cushion over canvas for seating purposes. Day room shall be available as temporary infirmary as well as crew's quarters, and shall have crew lockers, medicine cupboard, and shelves worked into after end, according to plan. The floor of the day room shall be removable, as described in section 1-4. Portable steps shall be provided at forward and aft ends to accommodate center tank fuel filling and suction fittings, as well as to provide an access cover over the fuel valves and piping on forward side of after bulkhead. Access to the after machine gun turret shall be through a door cut in the part of turret wall rounding out from the port aft corner of the day room. A stretcher handling door shall be cut in starboard aft bulkhead of the cabin trunk just above the transverse deck coaming, and shall open outward. Access doors to the tank manholes shall be cut in the side panels of the day room between the floor and the deck. In effect, all furnishings above the day room floor shall be easily removable, so that flooring and tank side panels may be removed for inspection or service of the tanks. Above the deck line, the day room shall have 3 windows each side, and one in the forward bulkhead for bridge communication. All windows shall have black-out panels (section. R-7). A fore and aft cabin top stiffener each side of the center line shall be shaped to form an overhead handrail. In the starboard forward corner, a hatch of at least 22 inches square shall be cut, with a hinge back top, to provide an exit from the day room, using a steel ladder with tubular rungs mounted on the house side. The entire center section of the cabin roof shall be mechanically removable, to facilitate the extrication of the fuel tanks.
The sides and top of day room trunk shall be constructed as described in section O-1, and shall include the after port .50 cal. machine gun turret, with main and depressed firing floors, limiting stops, exit door, and adequate drainage, as per plan.
