The Type XIV U-boat was designed to resupply other U-boats, being the only submarine tenders built which were not surface ships. It was nicknamed the "Milchkuh/Milchkühe (pl.)" or U-Tanker.
U-459 sinking after being attacked by Vickers Wellington aircraft.
The Type IX U-boat was designed by Nazi Germany's Kriegsmarine in 1935 and 1936 as a large ocean-going submarine for sustained operations far from the home support facilities. Type IX boats were briefly used for patrols off the eastern United States in an attempt to disrupt the stream of troops and supplies bound for Europe. It was derived from the Type IA, and appeared in various sub-types.
U-505, a type IXC U-boat
An engine order telegraph dial located in the engine compartment of U-505. "MT" is Maschinen Telegraf, (Telegraph Machine), and "Bb", indicating Backbord, (Port).