Help with a cross in gold winner

[John Brandon]

I know it's probably a long shot, but i am seeking any information on Kapitänleutnant Johannes-Martin Döpner.
Doepner was awarded the German Cross in gold on 9.9.1943. Kriegsmarine S boat commander. He was promoted to a Korvettenkapitän on 1.1.1945.

I cannot for the life of me find out what unit he served with, or what he won his decoration for.

Can anyone help, please

I have a presentation album given to him by his crew mates, but it is devoid of any names or units?

Any help would be gratefully appreciated..........Thanks

[Adrian]

I managed to find his name connected with: Flottilleningenieur in der 3. Schnellbootsflottille.

Döpner, Johannes-Martin - Kkapt.ing. 01.01.45. 3rd.S-Flot.ing.(05.40-06.43). "NURNBERG".(01.44-.

[John Brandon]

I managed to find his name connected with: Flottilleningenieur in der 3. Schnellbootsflottille.

Döpner, Johannes-Martin - Kkapt.ing. 01.01.45. 3rd.S-Flot.ing.(05.40-06.43). "NURNBERG".(01.44-.

I managed to get that far ade Thanks. Trouble is he is listed on the 3 flotila. But not commanding any s boats I can't find any pictures of him nor how he won his award. Frustrating!!

[Adrian]

I can't find him in the Lexikon der Wehrmacht either which is annoying.