Near-miss: ROV broke free of cargo strops during heavy seas

A member has reported an incident during bad weather in which an ROV which had been tied down broke free when the vessel was rolling heavily. The ROV started swinging on its supporting crane winch wire and narrowly missed personnel working nearby. No-one was injured; the ROV suffered slight damage.

The incident occurred whilst the vessel was waiting on weather in approximately 4m seas and 36 knot winds. The vessel was manoeuvring close to a floating production storage and offloading unit (FPSO) at the time and made a sudden turn, which caused an extreme roll. The stands upon which the ROV was stood slipped and the ROV itself moved, which caused its cargo strops to loosen. As a result the ROV began to swing on the crane winch wire, which was supporting the weight of the vehicle.

The ROV hit the bulkhead a number of times and narrowly missed two crewmen nearby. The crew managed to get the swinging ROV under control; the crane was started and the ROV lowered onto the deck, where it was properly sea-fastened and an assessment of possible damage then took place.

It was found that there had been some slight damage to the hydraulic hoses on the torque tool, which was attached to the ROV.

An investigation revealed the following:

  • The immediate cause of the incident was that the existing fastenings were not adequate to hold the ROV against an extreme sudden movement of the vessel;
  • Contributory factors were poor communication between bridge and back deck, poor judgement of sea conditions, and loss of concentration.