The after torpedo room carries 8 of the submarine's 24 torpedoes. Torpedoes were stored in the 4 tubes, with 4 reloads lashed to special racks called torpedo skids. The torpedo
tubes are made of bronze and the 4 polished breech doors for tubes #7 - #10 can be seen
in the after section. A torpedo tube is basically a large air gun that ejects a torpedo; the torpedo's own engine then carries it to its target. The 3,000 pound torpedoes were loaded into the tube by hand operated block-and-tackle. A storage skid was
pulled in line with a tube on the track and locked in place. Then the weapon was rigged into the tube with block and tackle. Amazingly this could all be done within just a few minutes.
Located on the skids are Mark 14 steam torpedoes. Each warhead contained 643 pounds of a high explosive called Torpex. A Mark 14 torpedo could travel over 4 nautical miles at a low speed setting of 31.5 knots, or more than 2 miles at its maximum speed of 46 knots. Steam torpedoes left a visible wake of exhaust gasses that pointed back to the submarine that fired them. The Mark 18 electric torpedo became available in 1943 and it had the tactical advantage of leaving no visible wake, although it could only travel at less than half the speed of the Mark 14. Pampanito was one of the first boats to carry the Mark 18.
Although the Mark 14 torpedo was an excellent torpedo at the end of the war, it was a fiasco at the beginning. At the start of the war the Mark 14 torpedo had 3 major flaws that made it difficult to isolate the problems that were leading to little damage being done to the Imperial Japanese Navy. The Mark 14 torpedo ran about 15 feet deeper than it was set. It also had a flaw in the contact exploder that caused it to not blow up even though it had hit the target. Finally, there was a flaw in the design of the top secret magnetic exploder that was supposed to blow up under a ship and break its back. After 18 months of work these problems were finally corrected, and the Mark 14 torpedo became a very dependable weapon. Who knows how much sooner the war would have ended if the torpedo had been properly tested during its development.
Imagine this compartment during a war patrol with 4 torpedoes on
skids, 4 torpedoes in the tubes, up to 15 bunks, the crew's personal
lockers, the bosun's locker, and storage for spare parts and tools. Men could be found sleeping, reading, studying, writing letters, or on watch - all simultaneously, all in this small compartment, all crammed together and yet all operating independently.
See a view underneath the submarine (in drydock).
Other Features of this Compartment:
Hydraulic Steering Rams: These operating rams are located outboard
of the torpedo tubes port and starboard. They are linked to the rudder and cause it to follow the movement of the helm. Helms or "steering wheels" are located in the Conning Tower and Control Room and are connected hydraulically to the steering rams.
Stern Plane Tilting Mechanism: The mechanism is located in the overhead between
the torpedo tubes. The stern planes were hydraulically controlled by a large, manually operated wheel located in the Control Room immediately aft of a similar arrangement used to control the bow planes.
After Escape And Rescue Hatch: This hatch has an emergency air connection for charging breathing lungs to allow escape to the surface. It was necessary to flood the entire compartment before this hatch could be used for escape.
Enlisted Head: Located on the port side of the watertight door forward. This was one of 4 toilets used by the 82 men. This one is special in that it ejected directly to the sea instead of into a storage ("sanitary") tank.
Enlisted Bunks And Personal Lockers: This compartment had normal bunks and small lockers for 12 men, and 3 additional bunks could be rigged if needed. In addition, after torpedoes had been fired the empty skids might be used as bunks.
Mark 18 Torpedo Gear: There is a battery charger located in the aft starboard
overhead and a hydrogen burner, to eliminate this explosive by-product of charging, located over the starboard torpedo tubes.
Gyro Angle Setter: Located against the after bulkhead between the torpedo tubes, this device received information from the torpedo data computer in the conning tower and automatically set the gyro angles which determined the course of the torpedo run.
Access To Main Ballast Tank #7: A manhole cover is located in the deck at the base of the visitor stairs. The top of this tank forms the deck of the compartment. Vent piping can be seen on both sides of the compartment. This proved to be problematic because the vents have full sea pressure in them when submerged and if they ruptured the compartment would flood. The Tench class submarines that followed the Balao class (Pampanito is Balao class) eliminated the vents inside the pressure hull.
Oxygen Cylinders: One is located in the overhead forward of the escape hatch, and two are located on the starboard side. They are painted green and were used to bleed oxygen into the atmosphere to extend submergence time or to charge escape lungs.
Signal Flare Ejector: Located on the port side forward of the torpedo tubes, this brass 3" diameter tube is operated similarly to a torpedo tube and was used to launch surface pyrotechnics. Various colored flares were carried that signaled different conditions to friendly surface ships and aircraft.
Fresh Water And Alcohol Tanks: Two large square tanks in between the frames on starboard side were used for fresh water for Mark 14 steam torpedoes. Alcohol, used to power steam torpedoes, was stored in similar tanks on the port side.
Storage Locker: Large locker on starboard side forward that contained emergency breathing lungs, life jackets, and miscellaneous storage.
Ladder: The large ladder and the hole above it were added when Pampanito became a museum. During her service there was a 21" round hatch here, angled down, and just big enough to pass a torpedo for loading. There was no ladder leading to this hatch because it was not used by personnel for access or egress.