German Sub Types
"The first submarines to be built for the Kreigsmarine, the Type IIC, were small coastal vessels, unsuitable for the mid and eastern Atlantic operations envisaged in Donitz's strategy. They were mainly employed in the Baltic for training purposes (Source)."
"Mainstay of the U-boat fleet for virtually the entire war was the Type VIIC. With a surface displacement of 770 tons, and 1,070 tons submerged, they had a crew of between 44 and 56, and a maximum surface speed of 17 knots, and 4 knots when submerged. With a surface range at cruising speed of 8,500 nautical miles and 80 when submerged, the Type VIIC proved capable of carrying the U-boat war to the eastern seaboard of the United States. The Type VIIC had 5 torpedo tubes, 4 in the bow and one in the stern, and carried a total of 14 torpedoes (Source)."
"Introduced shortly after the Type VIIC, the Type IXC was also important in the Atlantic campaign. Larger than the Type VIIC, the Type IXC displaced 1,120 tons on the surface and 1,540 tons submerged. She carried a crew of about 48, and had a speed approximately the same as that of the Type VIIC. The main advantage of the Type IXC was her range, 13,450 nautical miles on the surface, though only 63 miles when submerged, because of her greater displacement. She was also more heavily armed than the Type VIIC, with six torpedo tubes and capacity for 22 torpedoes. The main disadvantage of the Type IXC compared with the Type VIIC lay in a longer submerging time (Source)."
"Though these two types were built in by far the greatest numbers, they were not the only U-boats to be employed in the war. Several variants of the Type IX were produced, and larger vessels, the Types XB and XIV, made an appearance in small numbers in the role of unarmed supply submarines or "milch cows" designed to refurbish the attack submarines with torpedoes, fuel and foodstuffs. Very vulnerable, especially to air attack, they proved easy victims to Allied forces and were steadily hunted down (Source)."
"Of great potential significance both for the course of the war and for future submarine development, were the various experimental types of U-boat introduced or planned, mainly in the later stages of the war. The U-boats commissioned up until about the end of 1942 were not in fact "submarines" in the modern sense of the term, vessels in other words capable of operating almost entirely under water. They are better described as "submersibles", which operated mainly, and often most effectively, on the surface. The new generation of vessels under development in the closing years of the war began to change the face of undersea warfare (Source)."
"Most revolutionary, if it had appeared in time, would have been the so-called "Walther" U-boat, named after its inventor, Helmuth Walther, a minor employee at the Germania U-boat works in Kiel, who in 1934 approached the Naval Command with plans for a radical new type of submarine. Powered by a geared turbine, running on a hydrogen peroxide based fuel, the proposed U-boat would be capable of submerged speeds of 25 knots, greater than many surface anti-submarine vessels. Apathy, lack of resources and scepticism in the Naval High Command meant that developments were slow, and production promised to be to complex and hazardous for mass production. By 1942 it was obvious that the "Walther" would not be available in time to influence the current struggle (Source)."
"A meeting between Donitz and Walther in November 1942 led to the decision to concentrate in the interim on the "electro" submarine. These vessels had much greater battery capacity than the conventional U-boats, enabling greater underwater speeds and endurance, and, with the addition of the "Schnorchel" device to replenish air when submerged, able to stay under water for long periods of time. The "Schnorchel" was not in fact a German invention, having been used by Dutch long-range submarines prior to the war, but it promised greatly to reduce the vulnerability of the U-boat. Testing began in September 1943, with conversion kits being built for existing U-boats, but the first few newly equipped vessels were not in service until June 1944 (Source)."
"The "Schnorchel" device could sometimes be detected by radar or keen-eyed lookouts in calm weather, but although virtually impossible to spot in rougher conditions, these same situations often caused problems of their own. The float valve which closed the "Schnorchel" if its intake became submerged often caused a sharp fall in air pressure in the U-boat as air was sucked into the diesels, with resulting breathing difficulties and sometimes injury such as perforated eardrums. On several occasions air inside U-boats became so foul that crews were actually suffocated(Source)."
"The outcome of Donitz's decision were the Types XXIII and XXI. The Type XXIII was a coastal U-boat, with a range of 200 nautical miles submerged at a cruising speed of 4 knots. The larger Type XXI was a potentially very formidable weapon, which had a range of up to 15,500 nautical miles on the surface, and 365 miles submerged at 5 knots, though it could reach a submerged speed of 10 knots for just over 100 miles. Though claims that, had they appeared in 1943, these vessels would have won the Battle of the Atlantic for Germany are probably overstated, even as late as 1945, their possible use caused the allies grave concern, and it was fortunate that the war ended with only a few Type XXIII and only one Type XXI operational (Source)."