Ugh!
Give this a try?
Rescue Sub mod:
http://www.subsim.com/radioroom/down...o=file&id=3539
What mods are you using? How far into your career are you?
In Real Life, you could return on two engines... Or even one engine. Or use a radio. Or make sails out of the mattress covers and rig them to the periscope. Or swim for it. So I wouldn't consider it cheating to try to salvage a buggered save.
Either way you're going to have to violate "realism".