Unless I've missed it, I'm surprised nobody has mentioned "San Demetrio London", one of the most moving films from WW2, which my Dad took me to see during the war.
It's about the oil tanker
San Demetrio when hit by enemy fire, the crew abandon ship. But after several days adrift in a lifeboat, some of the crew find the ship miraculously still afloat. With courage and determination they steer the tanker home.
Couple of links here for anyone interested.
http://ww2today.com/6th-november-194...ard-their-ship
http://www.screenonline.org.uk/film/id/457226/
But then, perhaps you're all too young..........................
