Mooring & Berthing

A board placed between a vessel’s fenders and a rough or widely spaced berth face to spread contact loads. It bridges piles or irregular surfaces and prevents individual fenders entering gaps. The board and its lashings must remain positioned as the vessel moves with tide, wash and surge.

The hanging curve formed by a flexible line or chain under its own weight between supported points. In an anchor or mooring system, catenary can absorb movement and keep the pull more nearly horizontal at moderate loads. As load rises the line straightens, reducing this cushioning effect and increasing forces at the attachments.

To dislodge an anchor from the seabed after its cable has been brought near vertical. The vessel is normally manoeuvred carefully toward the anchor while cable is recovered, then controlled force is applied to free it. Windlass power should not be used to haul the vessel against heavy environmental loads or exceed equipment limits.

A securing arrangement that prevents an anchor moving unintentionally while a vessel is under way. It supplements the windlass brake and may use a stopper, pin, claw, wire or other approved restraint. The arrangement must withstand vessel motion and wave impact yet be capable of safe release when the anchor is required.

A strong shackle used to connect an anchor to its chain, swivel or cable. Its size, material and working capacity must suit the anchoring system, and the pin must be secured against working loose. The fitting should pass through the vessel’s bow equipment without fouling and be inspected for wear, distortion and corrosion.

The process of embedding an anchor and confirming that it is developing reliable holding power. After the anchor reaches the seabed, cable is paid out while the vessel moves away and load is increased progressively. Bearings, position, cable behaviour and engine load can help confirm the anchor has dug in rather than merely dragging across…

Backward movement of a vessel through the water. Sternway may be deliberately created by using astern propulsion or may result from wind, current or loss of forward momentum. Steering response can differ markedly from movement ahead, and a conventional rudder may be weak or initially ineffective until water flows across it.

A watch maintained to ensure that an anchored vessel remains safe and within its intended limits. The watch includes monitoring position, depth, weather, tide, traffic, cable lead and the vessel’s swinging circle. Alarms and electronic plots support but do not replace visual checks, good fixing practice and readiness to veer cable, start the engine or…

A mooring line led approximately at right angles to a vessel’s fore-and-aft line to restrain sideways movement. Breast lines hold the vessel alongside but provide little control of fore-and-aft movement, which is chiefly the role of spring lines. Their leads and loads must allow for tide, surge, passing traffic and changes in freeboard.