Introduction to Mooring Line

The mooring refers to any permanent structure to which a vessel/ship may be secured. Examples include quays, wharfs, jetties, piers, anchor buoys, and mooring buoys. A ship is secured to a mooring to forestall free movement of the ship on the water. An anchor mooring fixes a vessel's position relative to a point on the bottom of a waterway without connecting the vessel to shore. As a verb, mooring refers to the act of attaching a vessel to a mooring. Mooring is often accomplished using thick ropes called mooring lines or hawsers. The lines are fixed to deck fittings on the vessel at one end and to fittings such as bollards, rings, and cleats on the other end.

Mooring requires cooperation between people on a pier and on a vessel. Heavy mooring lines are often passed from larger vessels to people on a mooring by smaller, weighted heaving lines. Once a mooring line is attached to a bollard, it is pulled tight. Large ships generally tighten their mooring lines using heavy machinery called mooring winches or capstans. The heaviest cargo ships may require more than a dozen mooring lines. Small vessels can generally be moored by four to six mooring lines.

The Mooring Lines (or cables) used to secure a ship at a berth. Mooring lines should be arranged as symmetrically as possible about the midship point of the ship.

Breast lines – Mooring lines leading ashore as perpendicular as possible to the ship fore and aft line. Breast lines restrain the ship in one direction (off the berth).

Note: Due to collision with shore gantry cranes, breast lines are not used in container terminals.

Head lines – Mooring lines leading ashore from the fore end or forecastle of a ship, often at an angle of about 45 degrees to the fore and aft line.

Spring lines – Mooring lines leading in a nearly fore and aft direction, the purpose of which is to prevent longitudinal movement (surge) of the ship while in berth. Spring lines restrain the ship in two directions: headsprings prevent forward motion and backsprings aft motion.

Stern lines  – Mooring lines leading ashore from the after end or poop of a ship, often at an angle of about 45 degrees to the fore and aft line.

Number	Name	Purpose
1	Head line	Keep forward part of the ship against the dock
2	Forward Breast Line	Keep close to pier
3	Forward Spring	Prevent from advancing
4	Aft Spring	Prevent from moving back
5	Aft Breast line	Keep close to pier
6	Stern line	Prevent forwards movement