Berthing Alongside Rope Size Guide

Berthing Alongside Rope Size Guide

The following table gives a guide to the size of rope recommended for your Berthing Lines.

Primarily you should use Nylon berthing lines due to their superior elastic properties which are ideal for absorbing shock loading as the vessel surges forward and aft.

Some people use Polyester for their mooring lines because they have slightly better abrasive resistant qualities, but are a less elastic.

You should never use polyprop. for mooring lines because they degrade very rapidly with UV light, and can then part very easily. Also you should never use old halyards as mooring line, because the nature of their initial job as halyards was to stretch as little as possible, so, if old halyards are then used as mooring lines, there is a very good chance of shock loading deck cleats / fittings as the vessel surges at it's berth.

Boat lengthDayboat6m8m10m12m14m16m18m
Nylon Berthing Lines6-8mm8-10mm10-12mm12-14mm14-16mm16-18mm18-20mm20mm
Polyester Berthing Lines8-10mm10-12mm12-14mm14-16mm16-18mm18-20mm20-22mm24mm

It is recommended that mooring lines have a spliced soft eye at one end, for securing to a cleat. If a Bowline or any other knot is used, it will reduce the breaking strain of the mooring line by up to 40%. (See Section on Knots)

Note: The above figures are for rope supplied by South Wales Marine. You should always check the rope Manufacturers Tecnical Information as these sizes may vary due to rope construction and materials used.