The skipper of a fishing vessel had left the wheelhouse unattended before a collision with another boat, marine investigators have found.
The Peterhead-based Guiding Star sank following the incident with her sister vessel Guiding Light off Fair Isle near Shetland on 6 October 2022.
The eight crew were evacuated to a life craft which then capsized.
Five crew were then taken on board the Guiding Light and the remaining three were winched from the water by a coastguard helicopter.
The Marine Accident Investigation Branch (MAIB) has now published the findings of its investigation.
It says the two trawlers collided during a routine fish transfer.
The MAIB says the operation required the vessels to be close to one another, but rough seas and strong winds caused them to be pulled together and they collided.
A key safety issue identified by the report was that Guiding Light’s wheelhouse had been left unattended, which meant the skipper was unable to prevent the collision.
Floodwater immediately entered Guiding Star’s hull and the ship sank around an hour later.
The MAIB also found that the crew were unaware of the potential consequences of flooding, and that lifejackets and immersion suits were not accessible because they were stored in crew cabins which had flooded.
The Maritime and Coastguard Agency has been recommended to review its flooding prevention guidance to ensure the consequences of flooding on fishing vessels are highlighted appropriately.
The managers of Guiding Star and Guiding Light have been recommended to evaluate the impact of fishing operations on watchkeeping and make sure its crews are prepared for flooding emergencies, including making sure survival equipment is readily accessible.