Ship Design Minimum Breaking Load
The minimum breaking load of new dry mooring lines, for ships are designed to meet OCIMF standard environmental criteria restraint requirements. The ship design MBL is the core parameter against which all the other components of a ship’s mooring system are sized and designed with defined tolerances.
Line Design Break Force (LDBF)
LDBF is the minimum force that a new dry spliced mooring line will break at when tested according to appendix B. This is for all mooring line and tail materials except those manufactured from nylon which is tested wet and spliced. The values are declared by the manufacturer on each line’s mooring line certificate. See after appendix B on the manufacturer’s line data sheet. As outlined in appendix B, when selecting lines, the LDBF of a line shall be 100% – 105% of the ship design MBL.
The LDBF for nylon (polyamide) mooring lines should be specified as break tested wet because nylon lines change strength characteristics once exposed to water and generally do not fully dry to their original construction state.
Working Load Limit (WLL)
The maximum load of mooring line should be subjected to in operational service, calculated from the standard environmental criteria. The WLL is expressed as a percentage of ship design MBL and should be used as a limiting value in both ship design and operational mooring analyses. During operation, the WLL should not be exceeded.
In the same way that SWL is a limit for fixed equipment, the WLL value is used as a limit with the standard environmental criteria and mooring layout when designing mooring systems in establishing mooring system designs. Steel wire ropes have a WLL of 55% of the ship design MBL and all other cordage (synthetic) have a WLL of 50% of the ship design MBL.
Line Management Plan (LMP)
LMP is used to manage the operation and retirement of mooring lines and tails. The LMP also documents the requirements, assumptions and evaluation methods used in determining the line retirement criteria.
Mooring System Management Plan (MSMP)
MSMP will complement the ship’s safety management system. Which through a goal-based approach, core elements of the mooring system are identified, high level goals are established supported by more detailed functional requirements. A register of the mooring system components is maintained for the ship’s life in an accompanying Mooring System Management Plan Register (MSMPR).