Lack of Baseline Measure of Stability Sinks Vessel

Fishing vessel Nancy Glen

In a recent, accident investigation report, the Maritime Accident Investigation Branch (MAIB) of UK showed how a lack of proper stability measures can capsize a vessel. Here’s the detailed report as published on their website.

The Incident

  1. At about 1750 on 18 January 2018, the prawn trawler Nancy Glen (TT100) capsized and later sank in Lower Loch Fyne, Scotland. Weather conditions were benign, and rescuers were quickly at the scene; however, only one of the three crew survived.
  2. Nancy Glen was trawling at the time of the accident and the combined effect of a turn to starboard at the same time as the starboard net filling with mud caused the vessel to rapidly heel to starboard, then capsize.
  3. Through life modifications to the vessel had reduced its stability, increasing its vulnerability to capsize.
  4. Realizing the seriousness of the situation, one crewman dashed to escape. However, the darkness, disorientation, rapid nature of the capsize event and inrush of water to the wheelhouse will have denied the other two crew members the opportunity to escape.

Safety lessons

  • It is critical that fishing vessels have sufficient stability to meet their operating profile. Nancy Glen’s stability was insufficient to overcome the circumstances of a net digging into the seabed concurrently with the vessel turning.
  • Recent modifications to Nancy Glen had a detrimental effect on the vessel’s stability but no checks had been carried out to assess the effect on stability.
  • Although voluntary guidance was available, there was no mandatory requirement for owners of small fishing vessels to carry out stability assessments.


A safety recommendation (2019/109) has been made to the Maritime and Coastguard Agency (MCA) to ensure that the stability of all fishing vessels under 15m is assessed and regularly reviewed.

The Chief Inspector’s Statement

The capsize and sinking of Nancy Glen, which resulted in the tragic loss of two respected Tarbert fishermen, has again demonstrated the consequences of not knowing how stable a boat is. Too many of the UK’s small fishing vessels have no baseline measure of their stability, so their operators cannot assess the effect of material modifications or changes to fishing methods.

The MAIB has recommended that the Maritime and Coastguard Agencyimplements changes to legislation to require both new and existing small fishing vessels to assess their current stability and to continue to monitor this throughout the life of the vessel.

In parallel with this report a safety flyer has been released to the fishing industry highlighting the key lesson of the importance of measuring stability and notifying the MCA of proposed changes to a fishing vessel.

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Source: Maritime Accident Investigation Branch, UK



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