Near miss between ro-ro ferry Stena Superfast VII and Royal Navy submarine

Marine Accident Investigation Branch

July 15
23:00 2020

Accident Investigation Report 13/2020

Investigation report into marine accident including what happened, safety lessons learned and recommendations made:

MAIB investigation report 13-2020: Stena Superfast VII and Royal Navy submarine

Submarine periscope as seen from ferry

Submarine periscope as seen from ferry (photo: Stena Line)


At 1256 on 6 November 2018, Stena Superfast VIIs officer of the watch took urgent action to avoid a submerged submarine after its periscope had been spotted close ahead of the ferry. Post-event analysis showed that, prior to the ferrys course alteration, there had been a serious risk of collision. This near miss happened because the submarines control room team had underestimated the ferrys speed and overestimated its range, resulting in an unsafe situation developing. However, the submarines control room electronic tactical display presented a picture of a safer situation than reality; this meant that safety-critical decisions made on board the submarine may have appeared rational at the time.

Safety Issues

  • safety-critical decisions need to be made based on accurate information

  • passage planning should identify all potential hazards and effective mitigations

  • maintaining a good lookout is vital for the safety of all vessels


The Royal Navy has taken a series of actions in response to this and similar previous accidents. As a result, a safety recommendation (2020/124) has been made to the Royal Navy to undertake an independent review to ensure that the actions taken have been effective in reducing the risk of further collision.

Statement from the Chief Inspector of Marine Accidents

MAIB Report 20/2016 collision between a dived Royal Navy submarine and the fishing vessel Karen.

Published 16 July 2020