Passing vessels still relevant hazard for offshore installations?

We hear from time companies and individuals claiming that visiting vessels represent the only collision scenario to worry about for offshore installations in the Norwegian sector. Passing vessels, i.e. commercial shipping such as tankers, freighters, cruisers, etc. to or from Norwegian ports, or servicing northern Russian ports, may represent a threat to offshore installations in case of navigational equipment failure and/or failure to keep watch according to international rules and standards.

Such a scenario has never occurred in the Norwegian sector, although a Danish small freighter without watch on the bridge impacted the former Norpipe H7 compression platform in the German sector 20 years ago this month. Luckily this was a ‘glancing blow’, with minimal damage to vessel and platform. A dozen or so collisions have occurred in the UK sector, although the most recent was almost 15 years ago, none of the impacts caused severe damages to installations. But in the Gulf of Mexico there have been collapse of installations due to passing vessel collisions.

Petroleum Safety Authority has revised the definition of risk in January this year, placing more emphasis on uncertainty about what may occur. Especially in the light of this focus, it would not be prudent to neglect the threat of collision by passing vessels, merely based on the fact that such a scenario has never occurred in the Norwegian sector. We know of several anecdotal cases where just luck has prevented a catastrophe, when the vessel passed just a few meters to the side of the installation, without being identified and never responding to radio calls (before AIS became requirement).

In the Marine Technology Department at NTNU we have a Phd student with the task to update the COLLIDE collision model, which was established through a former PhD study more than 25 years ago. The revised model will still focus on passing vessel collisions, which we believe is not a hazard that can be neglected.

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