CORRECT!!! it is Otto Kretschmer. the highest scoring U-Boat captain of the entire war. he sank 51 ships equalling about 310,923 tons of shipping and warships sunk. he also survived the war, living untill 1998 when he died as a result of a car accident in Bavaria.
PS
Erich Hartman was in the Luftwaffe. Luftwaffe Personel were not allowed to grow beards. duh.