202031 Bow thruster sucks two lines

A tanker in ballast was berthing starboard side to in a strong current, running at nearly five knots. The Master was on the bridge and the vessel was under the guidance of a pilot. A small line handling boat was attending to help achieve the planned mooring pattern of three head and aft lines as well as two forward and aft spring lines.

To begin, forward and aft springs were set using the bow thruster at 70%, with the rudder at port 20° and the main engine running ahead as per pilot’s instructions, in order to keep the vessel close to the berth. Next, the three head lines were passed to the line handling boat forward.

Two of the head lines slipped off the bollard and more slack was payed out than needed. The lines floated on the water. Before they could be mastered by the launch personnel, they were entrained into the starboard inlet of the thruster tunnel, fouling the propeller blades.

Lessons learned

• Due care must always be taken with lines near a working bow thruster. Ideally, lines should not be allowed to float near a working bow thruster.
• Vessels in ballast have their bow thruster tunnels nearer to the waterline than loaded vessels and are at increased risk of mooring lines being sucked in.