What I have experienced onboard is that the numbers are usually available, but explaining why the WLL and brake setting are different is not always easy. The old understanding of “60% of the rope’s MBL” is still very much there, even when the documents now refer to SDMBL and LDBF. I recently wrote about this from a shipboard point of view and would be interested to know what others are seeing.
It certainly confused the hell out of me. Most vessels have the two junior officers at mooring stations and I suspect that if an inspector questions a just joined Second Officer,slightly jet lagged, who has yet to lay eyes on the mooring deck deficiencies will be forthcoming.
An interesting read that makes me appreciate being retired. I wonder how many Masters I sailed with could explain the origin of their ships SDMBL. I was AB in a couple of tankers during the 80s that parted a mooring wire that was disengaged and on the brake.
Having attended numerous vessels as a marine surveyor following surge incidents, I have seen both sides of this issue. I have witnessed mooring winch brake-rendering systems function as intended, preventing catastrophic mooring line failures, and I have also seen the aftermath when they do not—parted mooring lines, damaged equipment, and significant safety risks.
What concerns me most is that the industry continues to leave the determination and maintenance of mooring winch brake settings largely to the ship’s Master and Chief Officer. That approach is fundamentally flawed. These critical safety settings should not depend on onboard interpretation or judgment.
The naval architect, who designs the vessel’s mooring arrangement and specifies the mooring equipment, should determine the required brake rendering load during the design phase. That value should be permanently documented on the vessel’s approved mooring equipment drawings and other relevant technical documentation. Neither the ship’s crew nor a third-party surveyor should be expected to determine the correct brake setting independently.
Equally important, mooring equipment manufacturers should provide a robust, factory-designed, and permanent means of identifying the correct brake setting. Far too often I encounter improvised shipboard marking systems on mooring winch brake adjustment mechanisms that provide little confidence in the actual brake setting. Such ad hoc solutions are prone to error and are entirely inappropriate for equipment that serves as a critical safety device.
Determining the proper brake rendering load should be the responsibility of the vessel’s naval architect as part of the overall mooring system design—not a task delegated to shipboard personnel or left for surveyors to interpret years after the vessel enters service. And the marking system for the mooring winch brake settings should be designed and installed by the winch manufacturer — not delegated to shipboard personnel.