How Do Cruise Ship Anchors Work?

A cruise ship anchor holds the ship in place not just by its own weight, but mainly through the long, heavy chain it’s attached to. The anchor digs its flukes into the seabed, and the chain lies along the bottom so its weight and friction do most of the work. This only functions in relatively shallow water, which is why ships can’t anchor in the open, deep ocean.

It’s the chain, not just the anchor

People often assume the anchor’s massive weight pins the ship down. In reality, the system relies on scope: the crew lets out far more chain than the water is deep, often several times the depth.

That extra chain rests flat along the seabed. Its weight and the friction of the links dragging across the bottom create most of the holding power, and they keep the pull on the anchor nearly horizontal. A horizontal pull lets the anchor’s flukes bite into the seabed instead of being yanked straight up and out.

How much an anchor weighs

A large cruise ship anchor typically weighs in the range of 10 to 15 tons, and the chain attached to it can weigh even more across its full length. Each chain link is enormous, often heavier than a person. Ships usually carry two anchors, one on each side of the bow, both for redundancy and so the crew can choose based on conditions.

The anchor is raised and lowered by a powerful winch called a windlass, which handles the huge loads involved.

Why ships can’t anchor in deep ocean

Because the system depends on the chain reaching and lying along the seabed, a ship can only anchor where the water is shallow enough, generally up to a few hundred feet at most. In the middle of the ocean, where the seabed may be miles down, there’s simply no bottom for the anchor to reach.

This is why ships at sea never anchor. Instead, at deep ports without a dock, they use dynamic positioning, holding station with their thrusters and propulsion, while tenders ferry guests ashore.

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Part of our How Cruise Ships Work hub.