Mooring & Berthing

A vessel secured to the seabed by its anchor and not under way. It must display the lights and day shapes required for its size and circumstances and maintain an appropriate lookout. Swinging circle, depth, weather, traffic and risk of dragging remain active navigational concerns.

Fore-and-aft oscillatory movement of a vessel or floating structure. At a berth it may be driven by waves, swell, passing traffic or long-period harbour motion and can create repeated mooring loads. The term is also used more broadly for a rapid water-level change, so context should be stated.

To release a mooring or towing line so it can run free without recovering the end from the other attachment point. A slipped line is commonly doubled around a bollard or ring with both ends aboard, allowing departure without shore assistance. Crew must control the release and ensure the line cannot foul a propeller or…

To allow a rope to run out under controlled tension around a fitting or through a lead. Rendering prevents a sudden uncontrolled release while accommodating movement or reducing load. Hands and loose clothing must be kept clear of turns, fairleads and pinch points, and the tailer must retain a safe number of turns.

An anchor with a plough-shaped fluke designed to dig into the seabed as load is applied. It generally resets after moderate direction changes and is widely used on cruising vessels, although performance varies with design and bottom type. Correct size, scope and deliberate setting remain essential.

The movement of a moored vessel away from its mean or intended position. Wind, waves, current, tide and passing traffic produce surge, sway and yaw that load lines and fenders. Excursion limits must preserve clearance from the berth, other vessels, hoses, gangways and navigation channels.

The line or chain connecting a seabed mooring component to a surface buoy or vessel connection. It transfers mooring load through the water column and may include chain, synthetic rope, swivels and buoyancy. Corrosion, abrasion, fatigue and cyclic bending make inspection and compatible components important.

A substantial isolated marine structure used to secure mooring lines or assist berthing. Dolphins may carry bollards, fenders, access walkways or navigation lights and are positioned off a quay or terminal. Their safe use depends on line leads, rated capacity, vessel movement and local procedures.

Moving or turning a vessel by carrying out a small anchor and hauling on its line or cable. The kedge is placed in the required direction by boat or other means, then used to warp the vessel. The technique can help refloat, manoeuvre or hold a vessel but requires adequate holding ground, strong gear and…