First, ignore the green box, it isn't accurate. The docking module alone holds an 11x11x11 area centered on the ship's core, and the first enhancer boosts this to 15x15x15. All enhancers for the dock should be contiguous (touching another), having three lines running ftom the module will not work right currently, and each enhancer after the first that proceeds in a straight line along an axis will add 4 tiles to that axis (2 on each side of the core).
If your ship's core is not in the center of the ship, then even if the size of the docking area is the same as your ship's dimensions, it will not fit because the docking area is centered on your core - It doesn't just check your ship's size. Thus (non-tiny) ships with non-centered cores require more enhancers to extend the box to reach the rest of their ship (and at the same time are expanding it in the other direction away from the core into empty space).
11x11x11 test ship in a dock with no extenders:
Extenders should be in connected straight lines like this:
E
E
EEEEE
E
E
Or an L, etc. Like power.
This is bad:
EE
E
EE
This is also bad:
E
E
MEE
They do not need to be near or touching the module, just linked to it (c/v).
If your ship's core is not in the center of the ship, then even if the size of the docking area is the same as your ship's dimensions, it will not fit because the docking area is centered on your core - It doesn't just check your ship's size. Thus (non-tiny) ships with non-centered cores require more enhancers to extend the box to reach the rest of their ship (and at the same time are expanding it in the other direction away from the core into empty space).
11x11x11 test ship in a dock with no extenders:
Extenders should be in connected straight lines like this:
E
E
EEEEE
E
E
Or an L, etc. Like power.
This is bad:
EE
E
EE
This is also bad:
E
E
MEE
They do not need to be near or touching the module, just linked to it (c/v).