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How to Size an Anchor Chain

by Will Charpentier
The anchor chain of a large ferry boat.

The anchor chain of a large ferry boat.

An all-chain anchor rode -- the flexible connection between boat and anchor -- won't part because of abrasion, such as that which comes from anchoring to a sharp coral bottom, but it's hard on your deck. A rope-and-chain rode isn't as strong, but it's less expensive and maintenance is more flexible. Whether you use rope or chain for the majority of your anchor rode, correct anchor chain sizing is crucial to safe anchoring.

Size Matters

If you use a rope-and-chain anchor rode, the rope is connected to your boat's deck winch and connects the anchor. The chain's links must be 1/2 the diameter of the rope. The shackles with which you attach the rope to the anchor should be one size larger than the chain. If, for example, you use 1-inch rope as an anchor rode, you should use 1/2-inch anchor chain and 5/8-inch shackles. The chain portion of the rode should never be less than 20 feet in length, to provide enough weight on the bottom to hold your vessel in place. If you plan to use an all-chain rode, the bigger the diameter, the better -- as long as the links aren't too small to fit the cogs on your anchor windlass chain wheel. The length of the rode, whether rope or chain, should exceed 10 times the depth of the deepest water in which you expect to sail.

About the Author

Will Charpentier is a writer who specializes in boating and maritime subjects. A retired ship captain, Charpentier holds a doctorate in applied ocean science and engineering. He is also a certified marine technician and the author of a popular text on writing local history.

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