The Kapitänleutnant had to serve an average of 5 years or longer before being promoted to Korvettenkapitän (Dönitz needed almost 8 years in the twenties). During the war this time also became shorter.
In 1942 'Teddy' Suhren got his promotion after only 8 months!
The Korvettenkapitän wear the plain braid shoulder-strap (see left), the Korvettenkapitän (Ing.) has a cog-wheel on the shoulder-strap.
They had a broader stripe on the shade of cap. On the arm they wear three broad stripes and the star (engineer officers also wore the cog-wheel).
Commander of U-37
Korvettenkapitän 'Ali ' Cremer
Commander of U-333