You can sail between Scapaflow and Scotland just fine (sector Am14, right?) as long as you take some precautions:
Stay submerged during the day time, unless the weather is really bad. This will keep planes from spotting you.
Get through there as quickly as you can, but watch your fuel.
If you're surfaced, have a good watch crew on deck! It's important that they spot any ships as soon as possible, so you can take action.
Dive once in a while and see if you hear any ships (especially warships) that your watch may not be able to see. Adjust your course to avoid them.
Shallow water + Detected by Destroyers = Dead U-boat!
Once you're detected, your only hope is to try and become a hole in the water. That's impossible to do if you can't dive deeply. 60 meters and going flank is like saying "Here I am! Over here!"
Remember, some of the destroyers are capable of speeds up to 36 knots!! You will never out run a DD while submerged.
Basically, your situation was hopeless once you had 3 ships after you. So try to make that situation not happen again.
Good luck!
