Historically, the multiple definitions, test and calculation methods for mooring line break force ("MBL") have led to confusion between users and manufacturers and often a discrepancy between expected and actual mooring line performance (e.g. nominally similar mooring lines may in the past, have had a variation in tested break force of +/-10%). To resolve this confusion, OCIMF has collaborated closely with Eurocord, Cordage Institute, shipping industry NGOs, and OCIMF members to clearly define a set of terms and test methods for mooring line “MBL” that can be used consistently by both line users and manufacturers when designing, specifying, testing and operating mooring lines.
Traditionally, due to the use of the term ‘Minimum’ Breaking Load, many mooring line users may have evolved the misunderstanding that lines can be safely loaded up to their MBL with no failures or degradation. This is not the case and OCIMF is trying to heighten the understanding of the importance of safety margins on mooring lines.
MBL will be replaced with the following new terms: Ship Design MBL (MBLSD), Line Design Break Force (LDBF), and Working Load Limit (WLL).