Crane Hook Strikes Diver's Helmet

• During subsea spool tie-in operations, a crane hook unexpectedly struck a diver's helmet.
• Published 6 March 2025
• Generated 6 March 2025
• IMCA SF 04/25

What happened?

• Divers were working on the seabed in poor visibility during subsea spool tie-in operations.
• The Diving Supervisor instructed the crane operator to lower the crane hook to the seabed after landing the pipe handling frame (PHF).
• The instruction was to allow the diver to disconnect rigging from the crane.
• The crane operator reported 'no weight' on the crane wire.
• The Diving Supervisor then assumed the hook had reached the seabed.
• The supervisor instructed the diver to disconnect the PHF from the crane.
• The crane hook unexpectedly struck the diver's helmet while positioned beneath the PHF and moving up to disconnect the rigging.
• The diver was unharmed and returned to the dive bell, and the dive was aborted.
• The reclaim helmet was damaged beyond repair, but maintained integrity.

What went right?

• Diver 2 promptly assisted Diver 1, ensuring no injuries were sustained.
• The divers returned to bell safely.
• Both divers and the crane block had locating beacons fixed to them enabling accurate tracking.
• All procedures, lifting plans, and Job Hazard Analysis (JHA's) were followed throughout the operation.
• The protective equipment did its job, and the diver was uninjured because the impact was absorbed by the helmet.

What went wrong?

• The crane hook rested on the top beam of the PHF when lowered for PHF rigging disconnection.
• The resting resulted in a 'no weight' reading, leading the crane operator to assume the hook had reached the seabed.
• The hook slipped off the beam and struck the side of the diver's helmet as the diver approached the disconnection point.

What was the cause?

• Inadequate length of crane pennant/stinger did not provide sufficient distance between the divers and the crane hook.
• Poor visibility hindered the ability to accurately observe the position of the crane hook.

Lessons and actions

• Ensure adequate distance between divers and crane hook.
• The length of the crane pennant/stinger should be sufficient to maintain a safe distance between the divers and the crane hook during subsea operations.
• It reduces the risk of accidental contact with the hook, particularly in limited visibility conditions.
• Enhance visibility aids and monitoring by considering alternative methods in environments with poor visibility.
• Alternative methods involves additional locating beacons, underwater cameras, or sonar to better track the position of critical equipment like the crane hook.
• Improved monitoring can prevent misjudgements about the location of the crane hook.
• Reinforce communications and challenge assumptions.
• Assumptions regarding equipment position should be minimised.
• Clear communication and confirmation procedures between the dive supervisor, crane operator, and divers should be reinforced.
• Every party should be fully aware of the equipment's location at all times.

Member actions

• Updated project procedures to specify minimum pennant lengths for different operations.
• Conducted pre-operation inspections of all rigging and lifting equipment, including crane hooks and pennants, to ensure they meet safety standards and are appropriate for the operation.
• Updated the Job Hazard Analysis (JHA) to incorporate lessons learned from this incident, particularly regarding safe distances, visibility, and communication requirements for subsea lifting operations.