I've noticed in reference photos (at least accordng to the caption dates) German sailors wearing the flat top sailor hat up until the end of 1939; sometime in early 1940 this hat seems to be replaced by the German sidecap, or 'wedgie', and no photos show both caps being worn at the same time. Does this reflect a uniform change at the end of 1939? Gotta get my headgear correct for my 1/350 crews!