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Southampton Marine and Maritime Institute

Wolfson stability method recommended for under 15m fishing fleet

Published: 15 July 2016
Fishing boat wreck
Photo credit: MAIB

The UK Marine Accident Investigation Branch (MAIB) has recommended that fishing vessels under 15m length overall adopt stability criteria put forward by the University of Southampton’s marine technology consultancy, the Wolfson Unit.

The application of the Wolfson method, as it is known, was discussed in an MAIB report into the capsize and sinking of the fishing vessel JMT, which occurred in July last year off Rame Head, near Plymouth and resulted in the loss of two lives. The 11.4-metre vessel was operating in benign weather conditions and in daylight.

The report concluded that the vessel’s stability had been adversely affected by structural modifications and by aspects of the vessel’s operation, and that its capsize was possibly triggered when releasing the catch on deck. It further states that ‘only the Wolfson method would have provided an indication of the vessel’s operational limits and when caution was required’.

The method is based on the vessel size and provides guidance on the level of safety from capsizing in various sea states by means of a ‘traffic light’ chart and a freeboard mark applied on the hull.

Currently, fishing vessels less than 15 metres in length do not have to meet stability criteria but five stability methods are available and are described in MGN 427(F) (which is the Maritime and Coastguard Agency’s stability guidance for fishing vessels under 15 metres overall length). One of these is the Wolfson method, which stems from MCA Research Projects conducted by the Wolfson Unit, and provides guidance to vessels without stability data – such as fishing vessel JMT.

In 2015 MAIB appointed the Wolfson Unit to conduct a stability assessment of the vessel in typical loading conditions and in the likely operational conditions at the time of its loss. The stability assessment included a lines survey on the wreck, an inclining experiment and the calculation of several loading scenarios using a computer model prepared in Wolfson’s hydrostatics and stability program (HST).

As a consequence, a recommendation has been made to members of the Fishing Industry Safety Group to ‘explore ways to encourage owners of fishing vessels of under 15m [length overall] that are engaged in trawling, scalloping and bulk fishing to affix a Wolfson Mark to their vessels and operate them in accordance with the stability guidance provided’.

Notes for editors

An independent unit within the UK’s Department for Transport, the MAIB investigates marine accidents involving UK vessels worldwide and all vessels in UK territorial waters. The MAIB report may be obtained here.

For more information of the Wolfson Unit’s vessel stability and safety services, please see here.

 

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