Published on Australian Maritime Safety Authority (

Safety Lessons from Marine Incident Investigation (AMSA Report) No.12 – October 2022

Work boat capsizes while relocating shifted mooring.


On the morning of 19 August 2022, a work boat attended a shifted mooring approximately 100 metres off a river’s beach. Upon lifting the mooring, securing the chain to the vessel’s winch via the bow roller and proceeding, the mooring snagged on an unseen underwater object and the chain was pulled out of the bow roller and down the side of the vessel. The vessel capsized with no resulting injuries.  

What happened 

The master of a Class 2C work boat was tasked to relocate a shifted mooring approximately 100m off the beach of a South Coast NSW river. The master pulled the work boat alongside the mooring, then slung and moved the mooring via the onboard crane to the bow of the vessel and over the bow roller. The mooring was raised to the point where the chain could be hooked to the vessel’s winch and the crane was stowed. Once off the seabed about 2m, the mooring was tied off on the port side lug, 1.2m aft of the bow roller.  The master proceeded with the mooring over the bow at about 2-3 knots. The master was in the cab 8m aft and a deckhand was 2m aft and starboard of the bow. The mooring snagged on unseen debris, pulling the chain off the bow roller and along the port side gunwale. The vessel was then pulled over via the port side lug and capsized in approximately 2-3 seconds. The deckhand inflated their lifejacket, exited the water, and sat on top of the upturned vessel. The master, who was not wearing a lifejacket due to the confines of the cab, swam to the surface and got on top of the vessel. The work boat was tendered by a passing recreational vessel with Transport for NSW and Marine Rescue vessels attended. No injuries were reported.  

Investigation findings 

The investigation identified the following contributory factors: 

Safety message 

Proper risk assessments always need to be carried out for events where the potential hazards have not been identified in the SMS, whether this is for the appropriate use of personal protection and survival equipment, such as lifejackets, or the timing and water conditions for the conduct of a task. Appropriate wear of lifejackets while onboard DCV saves lives. 

Last updated: 25 October 2022