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 how to recognise the factors that create a 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 this 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
Concluding, it is important that owners and operators provide guidance, information and training to reduce the incidents of girding.