MAIB Calls for Closer Attention to Snapback Safety at Svitzer

The chief investigator at the UK Marine Accident Investigation Branch (UK MAIB) has written a warning to tug operator Svitzer to express concern that towline parting has become "normalized" in the company's operations, despite the risk to crewmembers when snapbacks occur.

The warning comes after damage to a Svitzer harbor tug and one crewmember in a rope-parting incident at Bristol. In July 2024, a tow rope on the tug Svitzer Avon (based out of Bristol's Royal Portbury Dock) parted after it had been used about 800 times. The crew rotated the parted line end-over-end and put it back in use, without conducting a residual strength test to determine its suitability for safe operations. The firm's towline risk management policy relied upon visual inspection and line rotation for safety.

On February 4, 2025 - about half a year later - Svitzer Avon was tasked with providing a ship assist to a car carrier, the Auto Eco. The Avon got under way shortly before 2000 hours, joined by fleetmate Svitzer Brunel. The relief master for Svitzer Avon was supervising the mate, who was at the helm.

The tug got in position astern of the Auto Eco at about 2003, and the crew passed over the towline. It was about the 1,100th time that the line had been used, having seen another 300 uses since its last rotation.

The towline was made up, and the tug got in position to provide braking force if required. The pilot instructed Svitzer Avon to provide "25 percent straight back" at about 2009.

Auto Eco then made a turn for a lock approach, and the mate aboard Svitzer Avon attempted to maneuver to maintain position astern while the car carrier was turning. The mate overcorrected, causing the tug to heel and imposing excessive forces on the towline. The line parted, recoiled and struck the wheelhouse of the tug, shattering the glass. Fragments of broken glass hit the mate and the relief master, causing minor injuries.

The mate and master determined that they were not seriously injured, then traded their tug's position with the Svitzer Bristol in order to complete the berthing maneuver. Only once the ship was safely docked did they return to their pier and seek medical care.

MAIB had previously reviewed a similar incident aboard Svitzer Mercurius in 2019 and had advised the company to undertake a fleetwide risk assessment of towline failure hazards and flying-glass injuries. In the Mercurius incident, MAIB found that the tug's windows were not designed to withstand a towline impact, and that the towing pennant broke at half its rated strength.

After the new incident on Svitzer Avon, MAIB's chief inspector called for the company to revisit its risk analysis and do more to minimize towline failures and reduce the risk of injuries in the event of a snapback. MAIB also noted that Svitzer has formalized its training practices; reviewed all towline parting incidents across its business; and taken steps to make sure that the right line is used for each application. It has closed the investigation.

Top image: Svitzer Avon (Marko / VesselFinder)