UK MAIB Investigation: Girting and capsize of tug Biter

UK MAIB has issued an investigation report on the incident of the girting and capsize of tug Biter with the loss of two lives while assisting passenger vessel Hebridean Princess in February 2023.

The incident

At about 1527 on 24 February 2023, the twin screw conventional tug Biter girted and capsized off Greenock, Scotland while attached to the stern of the passenger vessel Hebridean Princess, which was making its approach to James Watt Dock. Biter’s two crew were unable to escape from the capsized vessel and lost their lives.

The investigation found that Biter girted and capsized because it was unable to reverse direction to operate directly astern of Hebridean Princess before the tug’s weight came onto the towing bridle and, when this happened, the tug’s gob rope did not prevent it from being towed sideways. The investigation also found that Hebridean Princess’s speed meant the load on Biter’s towlines was between two and five times greater than at the port’s recommended speed range. Thereafter, given the tug’s rapid capsize, it was unlikely that Biter’s crew had sufficient time to operate the tug’s emergency tow release mechanism. Once the tug was inverted, the open accommodation hatch might have prevented air from being trapped inside the wheelhouse, potentially limiting the crew’s chance of survival.

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The investigation also found that the master/pilot and pilot/tug information exchanges were incomplete and that the opportunity to correct the pilot’s assumption about Biter’s intended manoeuvre was lost. Further analysis indicated that the training provided had not adequately prepared the pilot for their role and that it was likely the tug master did not fully appreciate the risks associated with the manoeuvre.

UK MAIB Investigation: Girting and capsize of tug Biter — Credit: UK MAIB

Conclusions

Safety issues directly contributing to the accident that have been addressed or resulted in recommendations

Biter girted and capsized because it was unable to reverse direction to operate directly astern of the passenger vessel before the tug’s weight came onto the towing bridle and when this happened its gob rope did not prevent it from being towed sideways.
Given that Biter’s emergency tow release mechanism was found to operate correctly post-accident, with just 10 seconds between the tug girting, flooding, and inverting, it is likely that its crew had insufficient time to release the tow ropes before the situation became irretrievable.
Hebridean Princess’s speed of 4.6 knots meant that the load on Biter’s towlines was between two and five times more than it would have been at the recommended lower speed of 2 to 3 knots. The higher speed meant that there was significant load on the gob rope securing arrangement, which almost certainly contributed to the gob rope rendering and the subsequent girting.
It has not been possible to determine exactly why Biter’s gob rope rendered; however, the practice of securing its gob rope to a samson post was untested and, combined with the low friction coefficient of the HMPE rope, might have allowed the gob rope to render more easily than if it had been secured by other means.
The configuration of Biter’s gob rope, anchored over a metre from the vessel’s transom and about half a metre above the tug’s deck, increased the tug’s vulnerability to being towed sideways and girted.
Biter’s watertight integrity was compromised when it girted and capsized because the accommodation hatch was open. This meant that it is highly unlikely that any air was trapped in the wheelhouse when the vessel inverted, limiting the crew’s chance of survival.
Although Hebridean Princess’s master was responsible for the safety of the passenger vessel, they relied on the pilot’s specialist ship handling and tug management skills to safely complete the passage and ensure that the actions of the ship did not endanger the tugs. This meant that a shared understanding between the master, the pilots, and the tug masters was essential for the safe manoeuvre into James Watt Dock.
Hebridean Princess’s master and the Clydeport pilot’s master/pilot information exchange was incomplete and did not discuss the capability, limitations, and hazards of operating the two conventional tugs.
The Clydeport pilot did not conduct a pilot/tug information exchange in line with the port’s towage guidelines. As a result, the two tug masters did not have a timely opportunity to influence the pilot’s intended plan for their employment.
The Clydeport pilot believed that Biter was operating in the same manner as an ASD and therefore did not understand Biter’s intended manoeuvre to take station astern of the passenger vessel.
Although Hebridean Princess’s master periodically reminded the pilot of the vessel’s speed during the passage to James Watt Dock, without a detailed understanding of the pilot’s plan for the tugs, the master was unable to effectively challenge the pilot’s directions to Biter.
Biter’s master started the peel off/drop back manoeuvre, judging the speed by eye, without challenging the pilot. This indicated that he did not perceive excessive risk to his tug.
The Clydeport pilot’s training had not adequately prepared the pilot to work safely with conventional tugs employed in ship assist towage.
The recently qualified Clydeport pilot had been allocated Hebridean Princess’s move because the passenger vessel was less than 100 meters in length and the complexity of the pilotage act and the risks associated with employing conventional tugs were not considered relevant. Had the move been assessed using the same criteria as a dead ship tow, then a more experienced pilot would have been allocated to this job.

Safety issues not directly contributing to the accident that have been addressed or resulted in recommendations

Had the tug master held a formal towage qualification, such as a Voluntary Towage Endorsement, he might have had a better understanding of the implications of the critical importance of the assisted vessel’s speed during this manoeuvre.
Biter’s deckhand had not completed the required induction training and this was his first day towing on a conventional tug at CMS. As a result, it is likely that his confidence in the role was limited.
Clydeport’s Towing Matrix assigned tugs within the port solely on the basis of bollard pull, rather than matching the capability of the tug to the intended task to ensure that the most appropriate tugs were assigned.
The guidance on the back of the seafarer’s medical fitness certificate (ENG1) was unclear and probably led to the decision by Biter’s master not to inform the approved doctor of his codeine use or hospital treatment.
There was no evidence that the tug master’s medication affected his ability to operate the tug.
Biter was not fitted with an AIS. As a result, the investigation was unable to accurately reconstruct the tug’s movements when outside CCTV coverage. Further, the lack of AIS in workboats and tugs meant that Clydeport’s Local Port Service and other mariners operating on the River Clyde and Firth of Clyde were unable to identify and monitor the movement of these tugs.

Action taken

Actions taken by other organisations

The Maritime and Coastguard Agency has issued Marine Information Note 701 (M+F) MLC49 and ILO50188: Reportable medical conditions during the validity period of a medical certificate. This provides further guidance on medical conditions that must be reported to seafarer medical certificate issuing authorities.

Clydeport Operations Limited has advised towage and workboat operators within the port that it intends to publish a General Direction for the port that requires all tugs and workboats to carry AIS transponders. It has also commenced a review of its towage risk assessments and guidelines.

Recommendations

Clyde Marine Services Limited is recommended to:

Review the company’s safety management system to provide clear guidance on the safe speed for conducting the peel off/drop back manoeuvre and the rigging of tug gob ropes.
Adopt an appropriate training and qualification scheme for its tug masters that is demonstrably equivalent to those specified in MGN 468 (M) and MGN 495 (M+F).

Clydeport Operations Limited is recommended to:

Commission an independent review of its tug training for pilots within the port.
Formalise the conduct of pilot/tug information exchanges and ensure that they are routinely carried out within its port.
Conduct a risk-based review of the Pilot Grade Limits and the Tug Matrix within its waters.
Consider requiring all tugs and workboats, that routinely operate within its statutory harbour area, to be fitted with and operate AIS transponders.

The UK Maritime Pilots’ Association, in conjunction with the British Ports Association, UK Harbour Masters’ Association, British Tugowners Association, and The Workboat Association, is recommended to:

Develop guidance for inclusion in the Port Marine Safety Code’s Guide to Good Practice and other appropriate publications that emphasises the importance of conducting a pilot/tug exchange, in addition to the master/pilot exchange, to ensure that the pilot, bridge team, and tug crew have a common understanding of the intended arrival/departure manoeuvre, the potential hazards, and their respective roles in managing them.

The UK Harbour Masters’ Association, in conjunction with the UK Maritime Pilots’ Association, British Tugowners Association, and The Workboat Association, is recommended to:

Develop for inclusion in the Port Marine Safety Code’s Guide to Good Practice, best practice guidance on matching the capability of the tug to the intended task to ensure that the most appropriate tugs are assigned.
Develop for inclusion in the Port Marine Safety Code’s Guide to Good Practice, guidance that harbourmasters require tugs and workboats that routinely operate within their statutory harbour area to be fitted with and operate Auto Identification System transponders.