The best, and most authentic way, is to download Hitman's Kreigsmarine Whiz-Wheel that you can find in this thread:
http://www.subsim.com/radioroom/show...ght=whiz+wheel
Here are a couple of pics of the one I built just to whet your appetite:
Just download the files in that thread, print them out, and put it together.
Strickly, all you really need is the back side, which will let you calculate speed and AOB given two observations of distance and bearing.
It works well, and is how they would have done it.