Ludovic,

The "crew" emblem as you refer to it is the emblem with the crossed marine daggers. It is the emblem of the class (kommandanten lehrgang) in wich captain Marbach got his "captainsdegree" Every "lehrgang" had its own emblem. The emblem in front of the conningtower was the Boats emblem. It is the portait of a black kat sitting on the bow of a submarine with on his head a white commanderscap. On his feet he wears (red) sea boots.In his left paw he holds a a raised pistol and in his right paw he holds two bottels of "Schnapps" (gin) It refers to the task of U-953 as "Flakfalle" or flakboat. The thougt behind this emblem was that one had to be intoxicated with alcohol (liquid courage) to fight back at airplanes on the surface. In other words, you had to be slightly mad to stay on the surface to fight airplanes off. U-953 became a "flakfalle" after the occasion that Marbach stayed on the surface on two occasions during one patrol when he was attacked by airplanes this in total negleckt of orders givven by the BdU that all U-boats had to dive when thy were attacked by airplanes.
The nickname/radiocallsign for U-953 was "U-Kater"

Kind regards,

Wiljan