How big were our submarines in WW2?

Most of our submarines were about the same size as the Pampanito. The boats built during the war were almost 312 feet long (311 feet and 9 inches) and 27 feet wide at the widest. The pressure hull (sometimes referred to as the people pipe) is 16 feet in diameter in most places, around 275 to 280 feet long and is tapered at the ends. The conning tower is about 20 feet long and 10 feet in diameter. Surface displacement is about 1,550 tons and submerged is about 2,400 tons.

These newer boats had 10 torpedo tubes – six forward and four aft – and a full complement of torpedoes was 24.

They had four main engine/generator combinations, plus a smaller diesel in the lower flats of the after engine room. The main engines produced around 1,500 horsepower each, whether they were built by Fairbanks-Morse or General Motors Winton.

The 40 or so “fleet boats” that were most of our submarines at the outset of WW2 were about 10 feet shorter than the Pampanito, a bit narrower and lacked the hard bulkhead to divide the engine rooms.

Some fleet boats had only eight torpedo tubes and others had ten. Generally, they only carried 20 torpedoes but some could carry four more in external containers. Their speed and range were comparable to the Gato/Balao/Tench boats. Many of them served throughout the war. These older boats had a higher loss rate than the Gato/Balao/Tench boats, due to the length of time they were in combat.

Initially, one significant drawback to these pre-war boats was in the engines. Some of these boats were outfitted with 9-cylinder Hooven-Owens-Rentschler (HOR) diesels. These engines turned out not to be reliable. (The sailors thought they lived up to their name –HORs.) The main problem was the failure of the timing chains. After a while, these engines would be removed and replaced with the larger diesels being used in the Gato boats.

The few S-class boats still in use at the beginning of the war were significantly smaller and had less range. That is why they became training boats as soon as we could afford to do so. They varied in size. Length was generally from about 220 ft. to 240 ft. Beam was 21 to 22 feet. Displacement was 850 tons to 903 tons on the surface. Submerged displacement was 1,060 to 1,230 tons. Maximum speed on the surface was 13 to 15 knots. Range was 5,500 nautical miles at 6.5 knots.