What is an Anchor Chain？
A Comprehensive Guide to Marine Mooring Systems
When a large oil tanker or a deep-sea drilling rig remains firmly anchored amidst rough seas and turbulent currents, its stability is due to a critical yet often overlooked component: the anchor chain. This sturdy, interconnected metal structure is the backbone of marine mooring systems, ensuring the safety of vessels and offshore structures even in the harshest environments.
In this guide, we explore the types, materials, grades, and applications of anchor chain, incorporating insights from industry leader SMEOCEAN, a global provider of marine mooring solutions certified by DNV GL.
1. What is Anchor Chain?
Anchor chain is a series of interconnected metal links designed to:
Secure a vessel (ship, boat, platform) to the seabed.
Absorb dynamic forces generated by waves, wind, and currents.
Prevent drift during operations such as loading, drilling, or fishing.
Unlike traditional ropes, anchor chain is heavier, stronger, and more wear-resistant, making it an ideal choice for long-term offshore use.
2. Key Components of Anchor Chain
A typical anchor chain consists of the following parts: Links: Individual metal segments (e.g., stud links for added strength). Shackles: Connectors that connect chain links or anchors. Swivels: Reduce torsion under load. End fittings: Connect to the vessel deck or mooring winch.
3. Anchor Chain Types
(1) Classification by link design Gripped chain: The most common type, with a crossbar inside each link for added strength. Used for offshore drilling, LNG carriers, and floating production storage and offloading vessels (FPSOs). Gripless chain: Lighter and more flexible, suitable for smaller vessels such as fishing boats. (2) Classification by material Carbon steel chain: Affordable, but prone to corrosion and requires frequent maintenance. Alloy steel chain (R3/R4 grade): Higher tensile strength (R4 ≥ 830 kN), suitable for deep-sea applications.
4. Anchor Chain Grade Description
Anchor chains are classified by strength class (e.g., U2, U3, R3, R4) based on:
Minimum Breaking Load (MBL).
Fatigue resistance under cyclic loading.
Grade MBL (kN) Typical Applications
R3 ≥690: Nearshore fishing, aquaculture
R4 ≥830: Deepwater drilling, floating production storage and offloading vessels (FPSOs)
SMEOCEAN Certification: All our anchor chains meet DNV GL, ABS, and LR standards, ensuring compliance with global offshore regulations.
5. How Anchor Chains Work
Deployment: The anchor chain is lowered from the vessel to the seabed.
Anchoring: The anchor sinks to the seabed while the chain's deadweight maintains it horizontally for maximum holding power.
Load Absorption: The catenary shape (natural curve) of the anchor chain acts as a shock absorber, reducing stress on both the vessel and the anchor. SMEOCEAN Engineering: Our dynamic simulation software optimizes anchor chain length and weight for specific sea conditions, reducing drift by up to 60%.
6. Anchor Chain Applications
Offshore Oil and Gas: Securing floating production storage and offloading vessels (FPSOs) and drilling platforms in ultra-deep waters.
Renewable Energy: Mooring floating wind turbines and wave energy converters.
Maritime Transport: Stabilizing LNG carriers and cruise ships in port.
Aquaculture: Anchoring fish farms and offshore cages.
7. Maintenance And Inspection
To ensure longevity:
Regular Cleaning: Remove salt and debris to prevent corrosion.
Non-Destructive Testing (NDT): Detect cracks using ultrasonic or magnetic particle inspection.
Lubrication: Apply marine-grade grease to shackles and swivels.
SMEOCEAN Services: We offer a global inspection team and predictive maintenance program to extend the life of your anchor chain.
8. Why Choose SMEOCEAN Anchor Chain?
Quality Certification: Complies with 13 classification societies, including DNV GL, ABS, LR, and CCS, and ISO 9001 standards.
Technical Solution Support: We can develop technical solutions based on customer requirements, simulating anchor chain tension in windy and sea conditions.
24/7 Support: From design to installation, our engineers ensure seamless integration.
Conclusion: The Foundation of Maritime Safety
Anchor chains are more than just metal links—they are lifesaving systems that protect vessels, crews, and offshore infrastructure. Whether for offshore platforms, offshore wind power, or global shipping, SMEOCEAN's high-performance anchor chains provide unparalleled reliability and durability.
Ready to Secure Your Next Project?
Contact SMEOCEAN today for a free consultation on anchor chain selection and mooring system design.
SMEOCEAN—Building Trust in the Toughest Waters. ⚓