Submarines ("U-Boots") were and are built at HDW dockyards at Kiel, Type 202 (Atlas Werke AG , Bremen) and the Type 207 ( Rheinstahl-Nordseewerke , Emden)
350 tonnes surfaced
450 tonnes submerged
Functions - They were designed to defend coastal (or littoral) Baltic-North Sea areas and with a total of 8 torpedoes or 16 sea mines
They were built out of a magnetic steel to counter the threat of magnetic naval mines, but this steel had been insufficiently tested and proved to be problematic in service with the Bundesmarine. Microscopic cracks in the pressure hull forced the cancellation of 9 of the 12 ordered submarines and the early retirement of the three completed boats. This led to the need for the Type 205s.
100 tonne surfaced
2 built for West Germany at Atlas Werke AG , Bremen, in service 1965-1966 then scrapped
205s mainly differed from the 201s in hull steel used. Various steels were tried in different 205 hulls. The most acceptable steel was found to be PN 18 S2, which was developed by the steel company Phoenix Rheinrohr . PN 18 S2 (is ST-52 the same steel?) has been used for all subsequent submarines for the German Navy up to Type 212A .
The Eleven Type 205s for West Germany were launched from 1962 to 1968 and operational between 1967 and 2004. The last 205 in service was U 12 eventually used as a test bed for new weapons systems until its retirement in June 2005.
Functions - Up until the fall of the Berlin Wall (1989) major peacetime functions most probably included providing a deterrent and electronic and special forces intelligence gathering missions against Warsaw Pact countries. If war broke out the 205's main function was to operate within the NATO structure specifically to defend against Warsaw Pact landing ships and other naval vessels threatening the Baltic and North Seas.
450 tonne surfaced
The following types were German designed and built but for export customers only - Type 207 (Kobben-"Seal" Class) and the Type 209
The 3 Gal ("wave") Class submarines for Israel (similar to the 206s) in service 1976-2002, 540 tonnes surfaced, 600 tonnes submerged, were German designed but for political reasons built in the UK at Vickers Shipbuilding and Engineering Ltd , Barrow-in-Furness
The first batch of Type 212 submarines used the Kongsberg-MSI-90U combat system. The Kongsberg system was used due to contra-trade obligations with Norway.
The second 212 batch use a Atlas Elektroniks combat system - perhaps the ISUS 90 or the more advanced ISUS 2000) .
The DM2A4 heavy weight torpedo (export designation SeaHake mod4) is in service with the 212s, has been delivered to the Pakistan Navy for service in Pakistan's Agosta 90B submarines and has been selected by the Spanish Navy for its new S80A submarines. The DM2A4 torpedo's sonar system has a wide angle array and the torpedo utilizes an at least 50km long fiber optic cable. Due to the bandwidth of optical transmissions the torpedo works as an additional sonar sensor for the submarine.
Wikipedia-English sources used so far
Wikipedia-German sources being used
Thankyou MHalblaub for drawing my attention to Wikipedia-German and other websites translated into English which have much more detail on German submarine matters :-)
Other German sources being used
http://seefahrer.blog.de/tags/uboot/ Seafarer or Sailor blog