Nancy Glen — The Crane That Changed Everything
Nancy Glen
Fishing vessel — prawn trawler · Lower Loch Fyne, Scotland · 18 January 2018
Source: MAIB Report 6/2019
The Situation
You're the skipper of a small prawn trawler under 12 metres. Over the last few years the boat has had a Kort nozzle fitted, the prawn tanks moved up onto the upper deck, and now — just before Christmas — a new 1,500kg crane has gone in, replacing the old 700kg one. Nobody has ever asked you to get a stability assessment done for any of it, and no regulation requires one for a boat this size.
The Lesson
Cumulative vessel modifications — each individually appearing minor — can progressively and fatally erode stability margins. Any change that alters weight or its vertical distribution should trigger a stability reassessment, whatever the boat's size.
Human Element
Each modification to the vessel was treated as a routine operational decision, with no regulatory obligation to seek a stability assessment. The cumulative erosion of the safety margin was never visible because no assessment was ever done — and the final reduction landed just weeks before the accident.
Try the First Decision
The new crane is in and working. It's roughly double the weight of the one it replaced, mounted high on the same boat that's already had two other modifications since 2002. You could get someone to run the numbers on what this means for the boat's stability before you go back out fishing — or you could get on with the season.
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