Concrete mattress beam lowered close to divers

What happened?

Subsea lifting operations were ongoing.

Two saturation divers were deployed on the seabed at 156 metres sea water (msw) to assist with a concrete mattress recovery.

A 696kg (1534lbs) mattress lifting beam attached to the vessel’s main crane was used for the task.

The mattress lifting beam was lowered too close to the divers.

The incident was not properly recorded and reported to management at the time it occurred.

Drawing of a concrete mattress lifting beam attached to the vessel main crane

Why did it happen?

The dive team lost sight of the beam during descent:

Lack of care and attention while the load was being lowered.
Remote operated vehicle (ROV) was on the seabed and did not provide eyes on the load from the short mark.
Poor visibility.

Failure to stop the job when the operating conditions weren’t safe (acceptance of risk).

What did they learn?

Ensure that:

Divers are clear of moving loads and maintain a safe distance at all times (NOT under the load, NOR in the ‘DROPS cone of exposure’).
Divers can see the mattress beam and are in a position to control the lowering of the load (by instructing the load operator via the dive supervisor)..
There is a ROV to determine water depth and height of subsea assets, locate the mattress beam and confirm its status.
The lifting beam is fitted with appropriate lighting (mini beacons, sticks, strobes etc.) and is lowered to the short mark above the assets or the seabed.
Beam deployment is conducted at a minimum distance from workers or equipment.
The crane line out meter is zeroed when loads pass through waterline.

Confirm all workers are aware of the incident reporting process.

Ask yourself or your crew

Have you ever been involved in a near miss like this? What happened?

What are risks associated with subsea diving operations?

What measures do we have in place to prevent this from happening during today’s subsea lifting operations?

What should you do if you saw someone working in an unsafe manner?

What is your incident reporting process?

What happened?

Subsea lifting operations were ongoing.
Two saturation divers were deployed on the seabed at 156 metres sea water (msw) to assist with a concrete mattress recovery.
A 696kg (1534lbs) mattress lifting beam attached to the vessel’s main crane was used for the task.
The mattress lifting beam was lowered too close to the divers.
The incident was not properly recorded and reported to management at the time it occurred.
Why did it happen?
The dive team lost sight of the beam during descent:
- Lack of care and attention while the load was being lowered.
- Remote operated vehicle (ROV) was on the seabed and did not provide eyes on the load from the short mark.
- Poor visibility.
Failure to stop the job when the operating conditions weren’t safe (acceptance of risk).
What did they learn?
Ensure that:
- Divers are clear of moving loads and maintain a safe distance at all times (NOT under the load, NOR in the ‘DROPS cone of exposure’).
- Divers can see the mattress beam and are in a position to control the lowering of the load (by instructing the load operator via the dive supervisor)..
- There is a ROV to determine water depth and height of subsea assets, locate the mattress beam and confirm its status.
- The lifting beam is fitted with appropriate lighting (mini beacons, sticks, strobes etc.) and is lowered to the short mark above the assets or the seabed.
- Beam deployment is conducted at a minimum distance from workers or equipment.
- The crane line out meter is zeroed when loads pass through waterline.
Confirm all workers are aware of the incident reporting process.
Ask yourself or your crew

Have you ever been involved in a near miss like this? What happened?
What are risks associated with subsea diving operations?
What measures do we have in place to prevent this from happening during today’s subsea lifting operations?
What should you do if you saw someone working in an unsafe manner?
What is your incident reporting process?