You may want to check out about Oskar Kusch:
http://www.ijnhonline.org/volume1_nu..._uboat.doc.htm
http://www.uboat.net/men/kusch.htm
(Prost to Oskar, who stayed a thinking man!)
Kusch's fate may have inspired Buchheim for the person of the 1.WO in Das Boot
Even if the approach towards nazi ideology may have seem a little more lax on an u-boat, there were no branches of the forces taht were an island in the brown swamp.