Robj250: You are a true submariner! If i were you, i would go for the eastern approach. Try entering during night, watch out for those shipwreks. sail between the, and when you enter the main "basin of scapa flow, dive to PD. run at 2-3 knots, and silent (dont want to wake those bad destroyers....Zzzzzz-Zzzzzzz) Hug the right shore on your way to the port (check depth, dont run aground..) Use periscope often. If you are detected, run like H*ll out the same way you came. The water is too shallow to survive i DC attack, so make your engines sing! And most important: Take the time you need, be tactical, dont stress anything! You will do this just fine! And then, you will no longer be a scapa-virgin....! Good Luck, fellow kaleun, i'll see you over a beer when you get back to port!
SH3Gen would probably be to no use, remeber: THE SAFEST WAY IS THE EAST APPROACH!