Between 2005 and 2018, the TSB Canada received reports of 26 girding (also known as girting) situations resulting in 21 capsizings. Girding occurs when a vessel is pulled broadside by a towline force and is unable to manoeuvre out of this position. The TSB has produced a video to illustrate the factors leading to girding and the recovery methods that can be taken in this eventuality.
Girding happens quickly and is a high impact event. When it does happen, the consequences can be serious. According to the video, when the TSB is called to a scene when girding has occurred, they often see that few operators have received instructions on how to recognise the factors that created the girding situation, and how to avoid or deal with it.
Factors that can lead to a girding situation:
(a) Suitability of the tug: size, power, manoeuvrability, power, and visibility.
(b) Towline length: When the two is overtaking the tug it can affect the tug’s stability.
(c) Location of the towing point: A sideways towline force creates a negative stability force which can cause the tug to capsize.
(d) Tow features: size, weight, momentum and pivot point.
(e) Environmental conditions: wind, current, tide, water depth.
(f) Watertightness of tug: Watertight integrity must be maintained to ensure the tug’s stability.
When more than one of these factors is not taken into consideration girding can occur causing a vessel to capsize. Operators can reduce the risks of girding by educating themselves of the dynamics on the dynamic of girding and understanding the different factors that contribute to it.
1 Adjust towline length and reposition tug in front of tow;
2 Using assist tug to reposition the tow;
3 Flop alongside: when the tug allows itself to be pulled alongside the barge until it can safely reposition.
A tug’s abort mechanisms should be:
– Highly visible
– Similar in style
– In familiar locations
In conclusion TSB Canada feels it is important that owners and operators provide guidance, information and training to reduce the incidents of girding.