Quote:
Originally Posted by Snestorm
Surprise.
The exhaust went into the main balast tank, filling it, and providing posative boyancy.
The germans didn't use compressed air for this. Smart idé. No smoke. Everything eventualy goes out the bottom. Makes for a good muffler too.
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You are referring to the KM method of blowing the residue out of the Main Ballast Tank after surfacing. This was a specialised function designed to avoid unnecessarily depleting the high pressure air banks. The RN and USN used a separate low pressure air blowing system to do this.
Ordinarily the engine exhausts did vent into the atmosphere. They can be seen ( above and in between the two rows of rectangular hull vents ) in the following photographs:-
http://www.uboat.net/gallery/index.h...95D&img=15
http://www.uboat.net/gallery/index.h...505A&img=8
http://www.uboat.net/gallery/index.h...534A&img=6
All in all I don't think the KM were unduly concerned about noise suppression on U-Boats. They weren't particularly noisy (even when running on diesels) and the amount of smoke generated during acceleration was minimal on a properly maintained engine.
However they did have a different attitude to the S-Boote where the later models did feature underwater exhausts. Mind you they did have three engines apiece and operated in packs.
