Nobody got it.
The answer was: A cargo hatch!
This is the location of the starboard section of Cargo hatch #4, with the other hatch in the corresponding location on the port side. The hint was the small crane on A deck above, used with these small hatches.
Cargo hatch 4 stopped at G and Orlop decks, where all the food was stored. The fact that these hatches were for loading food is also why the hatches and corresponding cranes were smaller than those on the rest of the ship.
Anyone can go next.