U-boat Projects and Proposals
Similar to type IA but with more additional storage space aft of the torpedo tubes for a total of 21 torpedoes or 42 TMA mines. 5 torpedo tubes (4 at the bow below the CWL and one at the stern), two 105mm/45 deck guns aft and fore of the conning tower. No contracts were granted for these boats.
Type III (modified 1934 project)
Originally known as the type VII, again similar to the type IA but with larger outer hull which could house 48 TMA mines. The design called for a large pressure-tight hangar for two 10-ton LS-boats. The project was abandoned due to its great expense and limited operational value.
Project for a supply and workshop boat for front line U-boats (similar concept to the Milk cows). No contracts granted for these boats.
Redesign of the type IA but with a steam propulsion, based on a suggestion by Schmidt-Hartmann. No contracts granted for these boats.
A 1937 design for a ocean-going minelayer U-boats. 4 mine-shafts like the XB with additional dry storage for mines and two mine launching tubes in the stern for SMA mines. 4 torpedo tubes at the bow below the CWL. One 105mm/45 deck gun. No contracts granted for these boats.
Type XI U-cruisers
Huge U-boats, designed in 1937-1938, with 4 127mm deck guns in two gun-towers (one fore and aft of the conning tower). 6 torpedo tubes (4 in the bow and two at the stern, all below the CWL). One Ar 231 small aircraft in a watertight 2.6m in diameter container shaft. These boats were to have a crew of about 110 men almost double that of any constructed German U-boat. 4 contracts (U-112 thru U-115) were awarded to the AG Weser yard in Bremen on Jan 17, 1939 but wisely cancelled at the outbreak of war in September that year and none of the boats had been laid down at the time (some sources mention U-112 as being laid down but that does not make sense).
These boats are often claimed to not only have been completed but sailed, usually on very clandestine missions and for good measure words like SS, Hitler, Bormann and the like are thrown into the mix. None of this is true and they very certainly not black as some suggest as it is somewhat hard to paint something that does not exist black.
Type XII Large U-boat project
A fleet U-boat design from 1938. 8 torpedo tubes, 6 at the bow and 2 at the stern, all below the CWL. This boat was to carry 20 torpedoes and no mines. The gun armament was to be the same as for the type IX boats. No contracts granted for these boats.
Type XIII Small U-boat project
Designed in 1939, this was a further development of the type II coastal U-boat types, with 4 torpedo tubes, all at the bow and below the CWL, one 2cm AA gun. No contracts granted for these boats.
Type XV and XVI large transport and repair U-boats
A preliminary design for very large (5000-ton and 3000-ton respectively) for transport and repair boats who would carry torpedoes, food and oil as cargo. The engine layout was to be the same as for the VIIC. No contracts granted for these boats.
Type XIX freighter U-boats
Designed by the OKM from the XB plans in late 1942. Those large vessels were nor armed with any offensive armament, only AA guns, as they were only for transportation of material. Those plans were preliminary for the type larger XX U-boats and no contracts were awarded.
Type XX freighter U-boats
Designed in 1943 by AG Weser and the OKM (German Navy High Command) as transport U-boats to carry material from the Far East. They were based on the type XB mine layers. They could carry 800 tons of material and they had no torpedo tubes and no deck gun, only AA armament. They were to have a crew of 6 officers and 52 men. 30 contracts granted, 15 to Deutsche Werft in Hamburg (U-1601 thru U-1615) and 15 more (U-1701 thru U-1715) to Vegesacker Werft in Bremen-Vegesack. Of those 30 contracts only 3 (U-1701 thru U-1703) were continued after 15 Aug 1944, but none was completed and their construction was halted in early 1945.
Type XXV small coastal U-boats
These vessels were to be a pure U-boats with electric-only propulsion and to operate as coastal U-boats. Roughly 160-tons with a similar hull to the of type XXIII. With a crew of about 58 men the would have 2 torpedo tubes fitted at the bow below CWL, 2 torpedoes only, no other armament. No contracts granted for these boats.
Walter type designs
Here I list only 4 of over 10 Walter-type designs that were drawn up 1937-1945 as the others had no hope of ever being built, let alone fight.
Project for a fast U-boat based on the Walter design. No contracts granted for these boats.
Type XXII coastal U-boats
Designed as coastal and Mediterranean boats by H. Walter GmbH. These was small Walter turbine boats with a crew of 2 officers and 10 men. They were to have 3 torpedo tubes, two at the bow (below the CWL) and one aft of the bridge (above the CWL). 72 contracts were awarded to Howaldtswerke (36 to the yard in Hamburg and 36 in Kiel), of those 72 only two actually ben laid down and had received U-boat numbers (U-1153 and U-1154) before they were all cancelled in the autumn of 1943.
Type XXIV project
A 1943 design to a ocean-going U-boat using the Walter turbine. It was to have 14 torpedo tubes below the CWL, six at the bow and 4 each side trailed aft (The Schnee Organ). 14 torpedoes, AA guns the same as for the XXI. No contracts were granted.
Laid down as high-seas U-boats propelled by the Walter turbine, they were to have a crew of 3 officers and 30 men. They were to have 10 torpedo tubes, 4 at the bow and 6 in a so-called Schnee organ, no AA guns. 100 contracts were awarded to the Blohm & Voss yard in Hamburg (U-4501 thru U-4600) and sections were under construction for U-4501 thru U-4504 when the war ended, the other contracts had been cancelled at the time.