Mooring operations are the most dangerous operations on board. When the choice of a mooring line is based on the wrong criteria, incidents are a challenge to face with.
We prepared a mooring lines calculation "cheat sheet" to avoid them. Use it to choose the right ropes' LDBF and DIAMETER for your vessel.
Use a simple FORMULA to calculate:
MBLSD (in tonnes) x 1.05 = right LDBF for your rope.
MBLSD (Ship Design Minimum Breaking Load) is the minimum breaking load of new, dry mooring lines for which a ship’s mooring system is designed.
You will find the number in the vessel’s mooring maintenance plan.
LDBF (Line Design Break Force) is the minimum force that a new, dry, spliced mooring line will break when tested.
For example, if a vessel's weight is 75 t:
75 x 1.05 = 78.75 t
Your preferred rope’s LDBF then should be between 75 t to 78.75 t.
Once you have a number, check your preferred rope’s specifications for its LDBF. The calculated number should be 100% - 105% of the SDMBL.
May your mooring activities be SAFE.