Definition of Mooring

Mooring refers to the process of securing a vessel to a berth or specific structure using mooring equipment, such as anchors, anchor chains, and winches. This encompasses various mooring operations, including berthing at a wharf, pontoon berth, or pile, mooring to buoys, and alongside other vessels. As a fundamental task in maritime operations, mooring plays a critical role in ensuring both vessel safety and operational efficiency.

Working Principle of Mooring Systems

To achieve a comprehensive understanding of the working principle of mooring systems, it is essential to identify their core components: mooring chains, mooring anchors, and mooring winches. Specifically, the operation of the mooring winch (either electric or hydraulic) enables the lifting and lowering of the anchor, ensuring the vessel is securely fastened at the berth.

Marine Chain

A mooring chain is a specialized steel chain designed to connect surface facilities with the seabed and provide secure anchorage. Its length is generally three times the water depth. The chain links are manufactured through processes such as welding and heat treatment, resulting in high strength and excellent corrosion resistance. Mooring chains are extensively utilized in marine engineering and the shipping industry. Based on varying tensile strengths, mooring chains can be categorized into multiple grades, including R3, R3S, R4, R4S, R5, and R6. Typically, the higher the grade of the mooring chain, the greater its tensile strength and the more intricate its production process becomes.

Mooring chains can be classified into the following types based on different usage environments:

• Ordinary mooring chains：mainly used for positioning and stability assurance of marine structures.
• Towing mooring chains：specially designed for cable towing operations in marine engineering.
• Traction mooring chains：suitable for marine towing operations, providing reliable connection and fixation functions.
• Anchor chains：mainly used for fixation during mooring or anchoring operations of ships at sea.

Mooring Anchor

An anchor, typically referring to a ship anchor, is constructed from cast or forged steel and serves as the core component of mooring equipment. The mooring anchor is connected to the vessel via a mooring chain and is deployed to the seabed using a mooring winch, ensuring the vessel’s stable mooring.

In deep-water environments, to guarantee sufficient holding power, a longer mooring chain is required to maintain contact between the lower end of the chain and the seabed, thereby enhancing the anchoring effectiveness.

Mooring Winch

A mooring winch (alternatively referred to as an anchor winch) is a mechanical device designed for anchoring, unanchoring, and cable handling operations. It is commonly installed on a vessel’s deck or onshore facilities.

Its primary functions encompass the deployment and retrieval of anchors, as well as the reeling in and out of cables. As such, it constitutes one of the essential components of a ship’s mooring system.