Two dropped object near misses

During a voyage in good weather conditions, the Captain decided that the vessel would sail with the cranes secured on deck. On the second day of the trip, the Captain was looking at the main hoist block of the forward crane, which was secured at the same height and just behind the bridge, when he noticed a 30cm long piece of 10×10 timber lying on the side of the hook.

The piece of timber was most likely placed there during a re-reeving operation some months previously, although the investigation could not confirm this and it may have been there even longer. The piece of timber was immediately removed.

Whilst disconnecting lifting gear from a large piece of subsea equipment, which had been loaded onto deck, it was noticed by the crew that a securing pin on the load was more than half out of position. The lifting gear consisted of a large beam and two further spreader beams. The grommets used for these spreader beams were secured with the securing pin, in turn secured with a safety pin. A few minutes later, the securing pin was touched by a steering line attached to the main beam, causing the securing pin to fall out and drop 15m onto deck. No-one was nearby where the pin landed; the loose pin had been spotted and the area cleared beforehand.

After discussing this incident with the crew, it was clear that the pin was secured with a safety pin of the correct size. What was not known was if the safety pin was still in good shape and not bent open or damaged in any other way. Also not known was if the safety pin fell out of the securing pin by itself (gravity) or if the steering line somehow pulled/pushed the safety pin out.

There was no direct force on the securing pin by the grommets. Due to the rigging, the spreader beam was twisted; it was horizontal but twisted some 30 degrees around its axis. This caused the pin to slide out when the safety pin was gone. The safety pin was not found after the incident.