You read my mind about part 135A.
Having invested some real brainpower into this now, I’m reasonably certain the crane was attached to the breakwater as was the case on Dresden. In the images below you’ll see it as the case.
So, I guess I was wrong about the circle being a collapsible crane. There is one possible reason for it, and that is it’s supposed to depict the capstan brake wheel position, but they got it wrong. That’s the only other fitting that’s on the port side of the ship near the capstan. So, what am I gonna do? I’m gonna cover that damn circle and pretend it didn’t exist! That’ll show ‘em!