[Justin Prince]

There was no "common type" of US submarine (unlike Germany), but WWII subs fell into five basic varieties.

The oldest were the Coastal Boats. These were the O and R class submarines, used for patroling the panama canal and for training. The O's had 4 18in tubes, the Rs 4 21in tubes, and each carried eight torpedoes.

The Most prolific before the Fleet boat were the S class, five (actually eight) different classes of submarines that numbered 51 in all:

Holland/Electric Boat S-1, S-17 (S-17 to S-41) and S-42 classes (S-42 to S-47)
Government/Lake S-3, S-4 classes (S-4 to S-9, S-14 to S-16)
Lake built S-2
And the 5 tube Lake S-10 (S-10 to S-13) and S-48 classes (S-48-S-51)

Note also that following damage, in the 1920's S-20 and S-48 were rebuilt and differed from their sisters. Officially (and I hope that Ubi follows the correct S boat classes I posted) they were Divided into five groups:

3 Prototype boats: S-1, S-2, and S-3 built by Electric Boat, Lake, and to a Goverment design respectively)
First Group - Goverment Design S-3 (S-3 to S-16; S-10 to S-13 actually were redesigned with 5 tubes ala the fifth/S-48 type, but were cramped as their hull was not lengthened)
Second Group - Holland/EB Design S-17 to S-41
Third Group - EB design S-42 to S-47
Fourth Group - Lake Design 5 tube S-48 to S-51, not successful.

The next type of boats are the Cruiser submarines, encompasing the Argonaut, Narwhal, and Nautilus. Argonaut was a 4 tube cruiser minelayer with 2 6in/53 deck guns, and the two Narwhals were six tube cruiser subs with 2 6in/53s. They were slow and unwieldy, and though they had (relatively) successful patrols, the WWI style role they were designed to fill never materialized. Argonaut was originally named V-4, Narwhal V-5, Nautilus V-6, leftovers from the 1916 V boat program that encompassed four different classes (V-1 or Barracuda, V-4 or Argonaut, V-5 or Narwhal, and V-6 or Dolphin. Cachalot and Cuttlefish were originally named V-7 and V-8 in design, but by the time the plans were finalized us subs had been named.

The next type are the prewar fleet boats, ranging from the Barracudas, (6 tubes, by 1928 a 3in/50 deck gun [original carried a 5in/51]), the Dolphin (a small boat, which Mush Morton called a deathtrap), the two Cachalots, the "P's" which were actually three similar classes: Pike, Shark, and Perch, 6 tubes (4 bow, two stern as all 6 tube boats), the similar Salmon and Sargo classes (8 tubes, 4 bow 4 stern), and the Tambor (10 tubes, 6 bow 4 stern) which are in effect slightly smaller Gatos.

The final type are the wartime fleetboats, The nearly similar Gato, Balao, and Tench class. They are the same sans for internal arrangement, diving depth (thanks to heavier side steel), and authorizing dates (Gatos are known as FY41 boats, Balaos as FY42, Tench as FY43).

The Fleet type (From Pike on) subs started with a single 3in/50 deck gun, but by wars end could mount a 3in/50, 4in/50, 5in/51, or a 5in/25 DP gun. Some later Balaos and Tenches (maybe even a few Gatos) could also carry two 5in/25s. These "gunboats" as they were called could either be ordered to carry this armament, or it could be chosen. US Deck gun armament was at commanders descrestion, either being mounted fore or aft or the type of gun. The 4in/50 was only standard on the S boats, but as they were scrapped, refitted, or retired for training a limited number became available.

The O, R, and Barracuda classes were used only for local US water patrols, Panama Canal patrols, or training. The S boats were used heavily in the Pacific and Atlantic during the first part of the war, but by late 1943 were used mainly for training.

The S boats bore the brunt of the early part of the war in the Philippines, and then saw use in the South Pacific and the aleutians. While the oldest US combat subs, they were comparable in size the the Type VIIC. They were cramped, hot, and rusty, but they did score several victories. Starting in 1943, they were used for training.

Dolphin, Cachalot, and Cuttlefish each made a few "zero" war patrols, and due to being unreliable, short ranged, and ineffective, were all relegated to training. Their main defect was being to short legged for a Pacific war.

The P's, Salmons, and Sargos were used well into 1944, and then used as "school boats" as more modern fleet boats came on line. Some P boats (plus the Salmon class Stingray, from mid 1942 until early 1943) carried external tubes, but these were not practical.

Argonaut was not employed as a minelayer, she was used as a patrol submarine and submarine transport, and was sunk in 1943. The two Narwhals were used as patrol subs, then converted to transport submarines until retired in early 1945.

The Tambors saw frontline service directly until 1945, and then were slowly retired. A few (I think) survived into the '50s.

The Gatos and Balaos bore the brunt of the war from 1943 on. There fairwaters (conning towers) were cut away, and by 1945 a prewar Gato armament of a single 3in/50, 2 .30 cal MGs and 2 .50cal MGs was usually 1 (or two) 3in/50, 4in/50, or 5in/25, 1 or two 40mm Bofors, and two (or if two bofors) one 20mm Oerlikon AA gun, plus a host of radars.

The Tenches were similar to the Gatos and Balaos, but they did not come online until 1945-46, and only 11 were able to make war patrols before the war ended. The Gatos, Balaos, and Tenches later served as the basis for the Guppy SSK conversions which formed the basis of the early Cold War diesel submarine fleet, plus formed the submarine fleets of dozens of countries.

The only other classes of US subs I didn't Mention where the Electric Boat Mackeral and the similar Goverment type Marlin. These were small coastal boats similar in size to the Cachalots, but were not effective. They were used for training (the Mackeral being used to film the movie "Crash Dive" with Dana Andrews, Tyrone Power, and Henry Morgan). Their main contribution is in the 1950s six updated Mackerals with Guppy style sails were built for Peru, of which I know they survived until the late 1990s, they may even still be around today.