I thought you might like a few pictures of U47 that I have been gifted by a relative.
The Sky remote is to give you some idea of the size of this model
The two pictures above show the motors, servo and battery compartment it looks to be ready for the water just requiring batteries and a remote control handset.
Last pic
U47 torpedoed HMS Royal Oak at her moorings in Scapa Flow
Wikipedia
http://en.wikipedia.org/wiki/German_submarine_U-47_(1938)