Pathos Miniatures said:
"So you mean that if i use not so "well known insignia" it woul be allright to do a "fiction" commander???
that does not make any sense cause every different insignia coresponds to actual persons and u-boat Crews."
Sorry - a bit of research could have helped!
The famous "sawfish-badge" for example, that at first - in green - only from U-96 (Kapitänleutnant Hinrich Lehmann-Willenbrock, the template for the movie "The Boat") was worn, was from 1942 to 1944 the insignia of the 9th Submarine flotilla (in Brest, France), as Lehmann-Willenbrock was appointed commander of this flotilla.
There it was in several different colors (black, green, red, white) from a number of different submarines worn - and also as a badge on the caps of their Crews and commanders.
This badge would have been far better suited, because it would have just given a number of alternatives for a "fictional" commander.
Cheers