The Republic of the Marshall Islands (RMI) Maritime Administrator has issued an investigation report regarding an incident of an explosion of a hydraulic windlass motor on board an RMI-flagged vessel.
The incident
On 28 September 2023 at 0435, the hydraulic anchor windlass motor on board a bulk carrier catastrophically failed when the anchor chain was running out unintentionally. The windlass clutch was engaged, but the winch drive was not operated. The windlass brake was closed. The burst motor resulted in flying debris which struck and fatally wounded the Bosun who was standing nearby.
The maritime safety investigation revealed that the movement of the ship in the existing sea conditions imposed dynamic loads on the anchor windlass and ground tackle that exceeded the combined brake capacity of the anchor windlass. This led to the parking brake slipping, followed by the rendering of the anchor chain, and resulted in the overspeed of the planetary gear and consequently a catastrophic failure of the hydraulic motor.
The windlass motor was not covered with a protection plate. The Bosun, who was standing in close proximity to the hydraulic windlass motor, was struck on his right leg by flying debris, resulting in an open fracture with arterial bleeding. External medical aid could not be administered before the Bosun was declared deceased.
Conclusions
The following conclusions are based on the above factual information and analysis and shall in no way create a presumption of blame or apportion liability.
Causal factors that contributed to this very serious marine casualty include:
- adverse environmental conditions preventing evacuation of the injured Bosun; and
- the dynamic load on the anchor windlass and ground tackle due to the movement of the ship caused by the existing sea conditions exceeded the combined capacity of the windlass disc brake and the parking brake.
Additional causal factors that may have contributed to this very serious marine casualty include:
- the absence of a protection cover around the hydraulic motor; and
- the anchor windlass not being subject to regular and routine servicing by a manufacturer service engineer.
Additional issues that were identified but did not contribute to this very serious marine casualty include:
- insufficient management of routine prescription medication being taken by crewmembers on board.
Lessons learned:
- Windlass motors have operating limitations and can fail. The operating limitations should be understood by the operating crew.
- A suitable protection system around the hydraulic motor offers protection to the operator in case of structural failure of the motor.
- General wear and tear can impact the holding capacity of the windlass. A periodical service by a recognized service station is recommended to improve holding capacity
Full advisory at the following link.