A fairlead is a fitting used to maintain or change the direction of a line, chain or cable so that it will be delivered "fairly" or on a straight lead to a sheave or drum with minimal friction. A warping fairlead is used during docking or mooring maneuvers or when shifting a vessel's position by pulling against a fixed point external to the vessel.
Warping fairleads are used to direct lines from a ship to the shore or to another fixed point off the vessel, allowing the ship to be maneuvered precisely over a short distance.
The simplest version of a fairlead is a single piece of steel fixed on deck. In order not to damage the cables or lines, the inner (contact) part of the fitting is smooth and rounded. Some fairleads are fitted with rolling cylinders in order to reduce friction.
The dimensions of the ship, the location of the fairlead, the dimensions of the line or cable and the fitting's specific applications are factors to consider.