Some of these links point to the same things:
http://www.subsim.com/radioroom/show...659#post851659
an older thread from 2008 that didn't get updated much
http://www.subsim.com/radioroom/show...189#post790189
http://www.subsim.com/radioroom/show...83#post2204183
and the grandaddy of them all:
http://www.subsim.com/radioroom/show...613#post835613
which if you're going to do German Uboats in SH4, you've got to at least try it...