THE MOORING SERIES — THEORY OF MOORING

The opening part of the “The Mooring Series”, devoted to the theory of mooring. Start with this one but also get two other parts dealing with the safe mooring practice and maintenance of mooring systems, plus a booklet. As a ship approaches port, officers and crew members shall prepare for mooring. When berthed, the ship’s mooring system must help ensure the ship’s safety and enable the cargo operations to proceed smoothly.

The purpose of mooring is to ensure that the ship lies securely and in correct position of the berth relative to the loading arms or cargo handling facilities no matter how the wind, waves or currents may affect her. In this video, we will look at the various forces the mooring scheme must withstand; the mooring at buoys will not be considered. The forces that act on a ship’s hull at the berth can be considered as having two components – transverse forces trying to move the ship away from, or toward the berth, and longitudinal forces trying to move the ship along the berth, forward or aft.

These forces may be caused by wind or by the movement of water, such as underwater currents, wave motion, and swell from passing vessels. Wherever possible, berths are designed to minimize the transverse forces. In practice, however, changing wind, tide, and sea conditions mean that such forces may present a load on the ship’s hull from any direction, effectively reinforcing or counteracting each other…