Grounding on uncharted bank of jack-up barge Octopus while being towed by tug Harald

Location: Stronsay Firth, near the Orkney Islands, Scotland.

Accident Investigation Report 18/2007

Read our marine accident investigation report, which includes what happened, actions taken and subsequent recommendations:

Harold&OctopusReport.pdf (2,518.51 kb)

Annexes (1,026.33 kb)


The jack-up barge Octopus was being towed from Kirkwall to Seal Skerry Bay in the Orkney Islands by the tug Harald, to act as a platform for the installation of a prototype tidal turbine. The tug and tow altered their route to pass to the west of Little Green Holm Island, due to the strong tidal streams experienced during the passage, a route not usually used by deep draught vessels. As the tug and tow rounded the south of Little Green Holm Island the barge, which was being towed with its legs extended to a depth of 13m, grounded on an uncharted bank of 7.1m.

Safety Issues

  • the tug skipper and the tow master relied upon 19th Century leadline surveyed charts for the passage of a deep draught vessel outside of a recognised traffic route
  • the passage plan and execution underestimated the effect of tidal stream on the tug and tow
  • depths that are significantly less than charted might exist around the UK coastline. The hazard of the bank was not identified as this was not charted


Recommendations were made to multiple organisations as a result of this accident investigation.

This report was published on 14 August 2007.

Updates to this page

Published 23 January 2015