MAIB reveals tug boat sinking in 10 seconds due to safety system failure 

The Marine Accident Investigation Branch (MAIB) has published its accident investigation report into the capsizing of the 16.25-metre tug Biter while towing the 67.1-metre passenger vessel Hebridean Princess towards James Watt Dock in Greenock on 24 February 2023. 

Claiming two lives – tug master George Taft and deckhand Ian Catterson – the incident occurred during routine engine and equipment trials of the Hebridean Princess. The tug sank in less than ten seconds and, according to the MAIB, was due to a “breakdown of systems that should have kept them safe.” 

The MAIB revealed several critical failings. The tug was affected by ‘girting’ forces and capsized when unable to reverse direction to operate astern of the Hebridean Princess. The crucial safety mechanism, the ‘gob rope,’ failed to prevent the vessel from being towed sideways. Additionally, an open accommodation hatch compromised the tug’s watertight integrity, limiting the crew’s chance of survival. 

Andrew Moll OBE, chief inspector of Marine Accidents, comments:  “Tug Biter’s accident was another cruel lesson of how rapidly things can go dreadfully wrong.”

The investigation also uncovered inadequate training of Clydeport marine pilots for working with conventional tugs like Biter and incomplete communication between the pilot, vessel master, and tug master. 

The MAIB has issued recommendations to Clyde Marine Service Ltd. to review its safety management systems and risk assessments, particularly regarding gob rope rigging and safe manoeuvring speeds. Clydeport Operations Ltd. has also been advised to commission an independent review of marine pilots’ training. 

“Small conventional tugs remain an essential part of UK port operations. However, the vulnerabilities of these vessels must be understood by those who operate and control them. 

“Harbour authorities, ship and tug masters, and pilots should collectively own this risk. Pilots and tug crews must be suitably trained and experienced for their roles and share a detailed understanding of the towage plan before starting the job. Speed, which exponentially affects towing forces, must be carefully controlled and the lines correctly set. Everyone involved must then monitor the execution of the plan and, if needed, act to keep everyone safe,” adds Moll. 

MIN regularly reports on MAIB’s marine accident conclusions. Further details about the Biter tug and Hebridean Princess are available to read and download online.