Girting and Tug Capsize
The girting failure mode, the investigated casualty record, the controls that work, and why conventional tugs dominate the statistics.
Girting, which the Transportation Safety Board of Canada calls girding, occurs when high athwartships towline forces pull a tug sideways through the water. If the tug cannot manoeuvre clear, the deck edge and bulwarks submerge, the heel increases and the tug capsizes. The tug Biter sank in less than ten seconds after capsizing off Greenock on 24 February 2023.
The casualty record is consistent. MAIB Safety Bulletin 1/2026 records that the Biter investigation was the eighth investigation involving the capsize of a conventional tug since 1998, a series that has cost nine lives. The Transportation Safety Board of Canada received reports of 26 girding situations resulting in 21 capsizings between 2005 and 2018. MAIB report 17/2024 quantified the controlling variable: the assisted vessel’s speed put towline loads two to five times greater than at the port’s recommended range of 2 to 3 knots.
The full article will set out the mechanism, the tow point geometry that decides exposure, the gob rope system and its limits, emergency release and why reports find it unusable in the seconds available, watertight integrity as the survivability factor, and each investigated casualty with its report number and date.