Fantastic skin

This is the dark "Schlickgrau 51" in which U-Boats like U-47 were painted.
Since you seem to have a taste for painting U-Boot skins, this article might help you a lot:
http://www.rokket.biz/models/modelsw...7/ubrass.shtml
Scroll down until you find "U-Boat colours and markings by Doug Martindale", it is probably the best info available nowadays on the subject.