IMCA provides lessons learned from an incident that involved damage to bulwarks, during the overboarding of a mattress stack using a mattress frame.
The incident
During the overboarding of a mattress stack (3x 150mm mattresses) using a mattress frame, the mattresses made contact with the port side bulwarks causing damage. Before and during the lift, the weather conditions were suitable for the operation.
As the load was lifted outboard, a swell caused vessel motion which led to a pendulum effect on the mattresses. The mattresses then hit the port side bulwarks causing damage. No-one was injured.
Probable cause
The immediate cause of the damage was that the mattress stack made contact with the port side bulwarks during vessel motion due to swell as the load was overboarded.
