The POST WORLD WAR II PERIOD

If World War I demonstrated the potential of submarine warfare, World War II demonstrated the potential of anti-submarine warfare. The later stages of the war and the immediate post-war period were probably the only times that the ASW forces enjoyed an advantage over the submarine. The only attempt to answer this vigorous ASW challenge lay in the developments of the German TYPE XXI, because it brought the submarine's preferred operating environment back underwater. It could be said that the history of the modern submarine begins here. All submarines before this time lacked underwater mobility; even Admiral Dönitz described his earlier U-Boats as little more than intelligent mines! The TYPE XXI was the first to employ high sustained underwater speeds during submerged maneuvers and attacks. It could defeat surface ASW escorts due to its high speed, deep-diving capability, and high maneuverability. It could essentially remain submerged all the time since it was equipped with a schnorkel.

However, the atomic age was here. Not yet the age of atomic propulsion, but the age of the atomic bomb and the sticky issue of whether or not the new bomb would make surface fleets obsolete. (The Bikini tests however, demonstrated that surface warships could survive an atomic blast.) So, what should be the role in the U.S. Navy in this post war period? Possibly some direct support to the surface strike forces, especially in the radar picket role or possibly an ASW role of submarine-versus-submarine to counter the increase in Soviet submarine? Plus, there was the problem of what should be done with the large number of now obsolete subs. Much of the immediate postwar submarine development activity was to determine new submarine roles and new missions.

Once again, after a major war at sea, where for the second time the role of the submarine had been so clearly defined, the post war period saw the submarine develop into way quite different from that of a general commerce raider. The reason that the WW II role of the submarine was so soon cast aside was the question of whose commerce would we raid? Whose sea lanes of communication would we interrupt? Russia was still a big land power with little ability for or apparent interest in, controlling the seas immediately after WW II. This led us to search for new uses for the submarine. If you thought the diverse designs following WW I were strange, just look at what the post WW II design programs generated:

Radar Picket Submarines (direct support of carrier task forces)
Hunter-Killer Subs (designates SSK and used for ASW only)
Cargo Submarines
Transport Subs (carrying troops and their equipment/vehicles)
Minelaying Submarines (project quickly dropped)
Submarine tankers (to refuel seaplanes)
Training and Target Submarines (one was a hit-shot target for exercise torpedoes))
Research Submarines (related to acoustic and sonar research)
Auxiliary Subs (a way to keep submarines yet not have them 'charged' against the Navy's attack submarine force levels
Midget Submarines
Guided Missile Submarines (more about these later)
and finally, the general purpose attack submarines (GUPPY, Fleet Snorkel modified and the new TANG Class)

With so many, now obsolete, submarines left over from the war, Congress was in no mood to outfit the Navy with a new generation of submarines. So the only alternative was a conversion program to make 'GUPPIES' from many of the existing fleet boats. It took about $2.5 million to convert a fleet boat into a GUPPY (for Greater Underwater Propulsion Power). And the result was a boat that could match the performance of the TYPE XXI except for the diving depth. Among the changes made were batteries with a 75% greater energy storage capacity and discharge rate, which resulted in an underwater speed of 17 knots for one hour. Whereas, a typical fleet submarine could only attain about 8 knots submerged, a properly streamlined GUPPY with high capacity batteries, could sprint up to 19 knots. Other new features (many adapted from the German TYPE XXI) included the snorkel, a more streamlined bow and fairwater (sail), new electronics and sonar systems, and the removal of all deck guns. To provide power to the new electronics systems and sonar transducers, one of the four diesel engines was sometimes replaced with a motor generator set.

The TANG class was our rough equivalent to the TYPE XXI. In order to increase the space for the batteries, the engine room size was reduced. But to compensate for this new (but not very successful) high power density 'pancake' diesel engines was installed. There were no deck guns nor was there a conning tower (the attack center being included in an expanded control room). The stern tubes only fired 'swim out' anti-escort acoustic torpedoes. This reduced armament (fewer torpedo tubes and no guns) was rationalized by the greater underwater maneuverability; how very different from the U.S. submarine operations of just a few years before. Another switch was that the submarines were now to be faster underwater than on the surface, which resulted in slow surface speeds during the long hours of battery recharging. They were designed specifically for snorkel operations and deep diving, 700 feet rather than 400 feet. Note - these fast submarines had to be designed to dive deeper to provide a safety margin during high speed maneuvers.

The need for very deep diving and long submerged endurance were in response to the ASW tactics of WW II where U-Boats were forced under, kept there by the extended allied air patrols and hunted to exhaustion by ASW hunter-killer groups. Now, in the postwar period there was a shift toward greater underwater maneuverability; necessary to evade modern ASW sonars and homing weapons (i.e. ASW torpedoes - rather than depth charges). Another change in design concept was in the amount of reserve buoyancy a submarine must possess. The large amount of reserve buoyancy, so important for surface seakeeping during World War II now became so much excess baggage as the postwar submarines tended to cruise underwater more and more ( which accounts for the limited freeboard and small ballast tanks of today's submarines).

More U.S. Submarines: A Technical History

S-Class (#111)
Pre-WWII Build-up and WWII Developments (#112)
Radar and Countermeasures (#113)
Post WWII Period (#114)
Missiles, Subs, and the USS Albacore (#115)
Early Nuclear Propulsion (#116)
Boomers and Fast Attack Submarines (#117)
Polaris and Other Missiles (#118)
Trident Missiles and Attack Subs (#119)