A recent IMCA Safety Flash focuses on an incident in which a lift bag got released unintentionally from crane hook.
What happened?
During a saturation dive, the deck crew connected a lift bag to the crane to send it down to the diver. When the crane hook went through the splash-zone, the lift bag came free from the crane hook and floated on the surface. As the vessel was in DP mode there was the potential for damage to the vessel´s thrusters and potential loss of the vessel’s position – while divers were subsea. No damage or harm occurred, but the event had the potential to cause considerable damage.
What went right
Deck crew noticed the danger and informed the bridge and dive control immediately. The current pushed the lift bag away from the vessel.
What went wrong
- The lift bag was not correctly attached to the crane:
- The lift bag was not folded correctly;
- It was connected to the crane through one of its webbing slings instead of being connected in such a way that would prevent the lift bag from being positively buoyant;
- The positive buoyancy of the lift bag allowed it to slide out through the safety hook passing the self-locking latch.
What were the causes
IMCA member identified the following causes:
- Lack of awareness: Inadequate safe rigging practice;
- Procedures not implemented: Double-check rigging before sending it subsea;
- Low-risk perception of the task.
Lessons and actions
Ensure thorough risk assessment and double-checking of the means for subsea lifting, before starting work. Our member recommended the use of a tool basket.
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Source: IMCA
