Two of the bow thruster motors need to be taken out of the Oosterdam, inspected and repaired. They are bow thrusters 2 and 3. A hole needed to be cut in the side of the ship, as the motors cannot exit the ship any other way. After inspection and repairs, the motors will be installed back on board and the piece of the hull that was taken out will be welded back in position. One can also see what the thickness is of the hull.
The white signs on the hull (circle with a cross in it) indicate the location of a bow thruster. One can see the Oosterdam has three.
The hull plate.