Hecht (Pike)
These 3-man midget-submarines were of type XXVII of which 53 (U-2111 - U-2113 and U-2251 - U-2300) were commissioned into the Kriegsmarine. Designed in 1944 to attach limpet mines to ships at anchor but the vessel was required to do more tasks which forced a change in design which proved unsatisfactory in most aspects.
This boat really had too limited range (78 miles at 3 knots surfaced and 40 miles at 6 knots submerged) for successful torpedo attacks. The first of 53 boats was delivered from Germaniawerft in Kiel, in May 1944 and 3 of these boats were outfitted with one magnetic mine holder instead of a torpedo but none of those saw action. The Hecht boats were only used for training purposes.

