Nautical German War Ensign, so called Kriegsschiffsgösch, 1933–1935 (and up to 1945 ceremonially). The Iron Cross on this flag is 2/3 width of flag. The Iron Cross is offset "a little bit to the hoist" (quoting FOTW). For a more rigorous treatment of the height of the Iron Cross across German flags see FOTW: Proportions of the War Ensign and Jack 1871-1935 (Germany)
Flag construction data from FOTW:

Proportions: [1]
Design: ibid. &amp; [2] (no black-red-gold canton)
Own work
Greentubing