I’m analyzing mooring operations as part of operational excellence at our company.
Mooring manufacturers are using much more improved materials then 10-20 years ago. This results in significantly stronger lines for same diameter. To recommend the correct MBL and die. of the line we should refer to the drawings and manuals. The OCIMF Mooring Equipment Guidelines suggest a terminology ship’s design MBL or alternatively if not able to find, the original lines provided by the yard.
Unfortunately many vessels doesn’t specify the MBL or material of the recommended lines, only the diameter. The alternative could be to use known winch capacity and apply correction factor of 22-33% as per OCIMF MEG4 ‘Winch motor - pull- between 22-33% at nominal heaving speed (ISO)’ of MBL. However, that seems to be too low, in example bulk carrier of 180m and recommended 63mm lines would have a MBL of around 600Kn with winch capacity of 100Kn. Following the guideline 100Kn/0.22 = 454Kn.
I’ve checked with global supplier and they simply follow Master’s advise and/or use factor of 2.5 of winch brake capacity, which is very different form OCIMF.
Any feedback on above would be welcomed.