Strong Current Pulled Bulk Carrier From Its Moorings -NTSB

A strong current caused a bulk carrier to break free from its moorings at the Convent Marine Terminal dock in Convent, La., on March 27, 2023, the National Transportation Safety Board said Thursday.

The Panamanian registered Sirocco was loading a cargo of coal when it broke free and drifted a half mile down the Mississippi River, colliding with a barge moored at the Mosaic Uncle Sam dock. No injuries or pollution were reported. Damage to the Sirocco, the barge and the Mosaic Uncle Same dock was estimated at $5 million.

An examination of the winch brake liners on the Sirocco’s bow found they exhibited extreme heat and friction, indicating that the tension on the forward mooring lines exceeded the forward mooring winches’ brake capacity, causing the lines to slip in a strong river current, resulting in the vessel breaking away from the dock.

“To reduce the risk of a vessel breakaway, it is important for vessel crews to understand the forces that act on a vessel when it is moored into a strong current at a dock,” investigators said. “Crews should ensure that slack is taken out of lines as the vessel loads, especially as the forward draft increases and the bow begins to sit lower in the water, exposing more of the hull to the current. Continuously monitoring and taking up any slack from bow lines as forward holds are loaded can help to ensure that the bow does not come away from the dock.”

The NTSB also said that developing a response plan for a breakaway can ensure that crews are prepared to respond when one occurs.

“Vessel masters should also consider incorporating additional safety measures such as keeping propulsion, thrusters, and steering systems on short standby and having anchors ready for immediate use (even if not required by the loading facility),” investigators said. “Vessel masters should be familiar with how to request tug support on short notice.”