Hi,
my guess is Lemp's U-30. The emblem depicts Lemp's terrier "Schnurzl" and was applied on 10 Aug 1939, then moved upwards and forward on the turret sides, when the boat received her turm modification and had the L-shaped air trunks added. Curiously, the inignia sports a dark background on the port side and a white (i guess) background on the starboard side.
Cheers!
SG
PS Well done Kennoz, keep up the great work, am looking forward to seeing the boat weathered properly!