Anchor Shackle Chain Requirements for the Size of the Boat

Written by patricia linn
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Anchor Shackle Chain Requirements for the Size of the Boat
Researching the best type of anchor for optimum safety at sea is an important consideration for every mariner. (anchor image by Hassan N from

An anchor chain rests on the sea floor and keeps the anchor "dug in" properly, thus reducing the possibility of the vessel dragging the anchor and possibly crashing into other vessels or running aground. The more chain and rode (rope) that are let out, the less likely the anchor is to move. When anchoring where there are no other vessels and plenty of space, putting extra rode--even without chain--would theoretically be effective. Usually, however, anchorages have other boats and structural or landmass obstacles so excess rode should not be deployed; that is when an anchor chain becomes absolutely necessary. Anchor rode with chain is deployed at five to one scope, which means if the water is 10 feet deep, a minimum of 50 feet of line must be deployed for effective anchoring (more if it is windy). The following specifications err on the side of safety and assume six to 30 feet of chain depending on the vessel's weight and its load carrying capacity.

14 Feet to 24 Feet Length Overall (LOA)

From dinghies to beach catamarans, and flat boats to sport fishing vessels, all sailors will need to anchor at some point. In this vessel size range, 3/8-inch three-strand nylon rode and 3/16-inch chain is suitable.

25 Feet to 31 Feet LOA

Smaller cruising vessels in this size range need 7/16-inch three-strand nylon rode and 1/4-inch chain.

32 Feet to 37 Feet LOA

Medium size cruisers and speedboats will do well with 1/2-inch three-strand nylon rode and 1/4-inch chain; if the vessel is heavy, add length to the chain based on the owner's manual recommendations.

38 Feet to 45 Feet LOA

Vessels over 40 feet are heavy enough to warrant longer chain lengths; 9/16-inch three-strand nylon and 5/16-inch chain are recommended.

46 Feet to 52 Feet LOA

Vessels in this size category should have no less than 12 feet of chain at 5/16 inch with 3/4-inch three-strand nylon rode.

53 Feet to 60 Feet LOA

For these larger vessels, a minimum of 3/4-inch three-strand nylon rode and 3/8-inch chain are desirable.

61 Feet to 70 Feet LOA

Three-strand nylon rode with 1/2-inch chain should be effective for sail and powerboats in this category.

71 Feet to 80 Feet LOA

These big vessels should have 30 feet of 5/8-inch chain and plenty of 1-inch three-strand nylon rode.

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