Boat had no chance.
The crew of seven on the Harvest Hope barely had time to scramble into a liferaft before the vessel capsized and sank.
An official report revealed yesterday that the 91ft vessel's nets had caught on a huge pile of boulder clay left over from burying a North Sea oil and gas line.
The Marine Accident Investigation Branch of the Department of Transport also found that the line - from Shell's Goldeneye development - had not been marked on any official charts.
The trawler sank in August last year as it fished around 40 miles off Peterhead.
The crew were picked up unharmed by another fishing boat.
Shell said last night they were trying to remove the obstruction.
SANK: Harvest Hope