Fairlead

A fairlead is a deck fitting whose purpose is to lead a rope or mooring line fairly (that is, smoothly and in the intended direction) so that it runs without a sharp bend, without chafing on the ship's structure, and at a suitable angle to the fitting or winch it serves. When a ship is moored, its lines run from winches and bitts on deck, over the ship's side, and across to the bollards on the quay, and without guidance they would rub over sharp edges, take poor angles, and wear or part. The fairlead solves this by providing a smooth, strong opening or set of rollers through which the line passes.

Fairleads take several forms. A simple closed fairlead, sometimes called a Panama lead because such enclosed leads are required for transiting the Panama Canal, is a strong oval opening in the bulwark or a fitting through which the line is led. Roller fairleads contain one or more rollers that turn as the line runs over them, greatly reducing friction and chafe, which is valuable where lines move under heavy load. Universal or pedestal roller fairleads have rollers arranged so the line can lead in almost any direction. Each is built strongly, because the forces in a mooring line are large.

By controlling the direction and angle of the mooring lines, fairleads are important both to the effectiveness of the mooring (a line pulling at a good angle holds the ship better) and to safety, since a well-led line is less likely to chafe through and part. They work together with the bitts, bollards, winches and capstans of the mooring system. In arranging a ship's moorings, the officer considers how each line is led through its fairlead to the shore, so that the pattern of lines holds the vessel securely against the movement of wind, tide and passing traffic.