A recent incident investigation concerning the sinking of the vessel Bourbon Rhode on 26 September 2019 in the Atlantic Ocean, revealed a safety issue which is of great importance.
To remind, the Bourbon Rhode sank on September 26 in the Atlantic Ocean during a transit voyage form Las Palmas to Guyana.
The anchor handling tug was equipped with a system called shark jaws1, installed in the aft Z-Drive compartment, to secure chains or wires during anchor handling operations. When operating, water from the deck can enter the watertight housing frame, which has three drain fittings at the bottom plate. When not in use, the shark jaws are lowered into the housing frame and are flush with the deck. In lowered position, gaps around the shark jaws allow water to enter the housing frame.
Probable Causes
#1 The investigation revealed that under unfavorable circumstances, the water quantity penetrating the compartment is likely to increase up to a point where, when unnoticed or unattended for a certain period of time, an unsafe condition may develop and lead to a major flooding with subsequent foundering.
#2 In addition, the investigation revealed other anchor handling vessels in his fleet with leaking inspection covers of the anchor handling systems. This means that the compromised watertightness of the anchor handling systems equipped with this type of inspection covers is not an isolated safety issue, but is likely to be encountered at a systemic level.
Safety Issues
The report highlights that
As an immediate safety measure, it is recommended to put in place an additional safety barrier through the SMS by implementing a procedural defense to limit the risk of flooding from leaking inspection covers of anchor handling systems.
Along with the existing maintenance instructions, the report notes the following as safety actions to be taken:
- Preventive actions to mitigate the risk of water ingress through the inspection openings during maintenance tasks on the anchor handling systems (e.g. sea state limitations, installation of anchor handling system deck cover plates);
- Instructions for the appropriate sealing method when installing the inspection covers to ensure the watertightness of the anchor handling system housing (e.g. application of silicone sealant, installation of gasket);
- Instructions for testing the watertightness of the anchor handling system after completion of the works and installation of the inspection covers (e.g. flooding of anchor handling system housing frame with closed drainage by use of fire hose).
- Maintenance actions to prevent a degradation of the inspection covers and securing devices, which could compromise the watertightness of the anchor handling system;
- Appropriate documentation of the actions performed during the maintenance work.
