How to identify the size of an anchor chain

Written by dawn sutton
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You can identify an anchor chain and determine what kind of boat it is appropriate for by its weight and chain diameter measurements. You can manage a small boat, less than 30 feet long with a short chain attached to a nylon line. Larger vessels require a longer chain, known as the anchor rode, made of heavy chain links.

Skill level:
Easy

Things you need

• Anchor chain
• Construction tape measure
• Large, heavy-duty scale
• Hoist/crane

Instructions

1. 1

Lay the anchor chain out lengthwise on a flat surface. Measure its length with a construction tape measure which can measure items from six feet to 200 feet long. A boat that is 20 to 25 feet long should have a 90-foot anchor chain. The chain should be 135 feet for boats between 26 and 30 feet long. For a boat that is 31 to 35 feet long, the chain should be 190 feet long. You need a 225-foot chain for boats which are between 36 and 40 feet long. Boats that are 41 to 45 feet long should have a 240-foot chain. If your boat is between 46 and 50 feet long, then you will need a chain that is 315 feet long. You will require a chain of 360 feet for a boat that is 51 to 60 feet in length.

2. 2

Measure the diameter of the links with a tape measure. A boat that is 20 to 25 feet long should have chain links that are 3/16-inch in diameter. For a boat between 26 and 30 feet in length, the chain link diameter should be 1/4-inch. Your chain link diameter should be 5/16-inch if your boat is 31 to 35 feet long. A boat which is 36 to 40 feet in length requires a chain link which is 3/8-inch diameter. The chain link diameter should be 7/16-inch if your boat is 41 to 45 feet long and 1/2-inch for boats 46 to 50 feet in length. A larger vessel which is 51 to 60 feet long requires a chain link diameter of 9/16-inch.

3. 3

Weigh the chain on a large, heavy-duty scale. Steel chain links are extraordinarily heavy, so an anchor chain which is 90 feet long on a smaller boat of 20 to 25 feet should weigh 1134 Kilogram. A medium-size boat that is 36 to 40 feet in length should have an anchor chain that is 225 feet long and which will probably weigh about 6.8 Kilogram. A large boat that is 51 to 60 feet in length should have an anchor chain that is 360 feet long and should weigh up to 22680 Kilogram. In order to weigh an extremely heavy chain, you could use a weigh station scale at a truck stop, and you would need a hoist or crane to place the chain on the scale.

4. 4

Compare the difference in weight measurements on a weight conversion chart, if necessary, as anchor chains can be measured in ordinary pounds such as the ones on a typical body weight scale or in Bruce pounds, Danforth pounds, Fortress pounds, Plow pounds, or Yachtsman pounds. For example, a small boat which is 20 to 25 feet long would have a chain that would weigh 2,500 in regular pounds. That would equal 4.4 Bruce pounds, 8-S/5H in Danforth pounds, 4 Fortress pounds, 10 Plow pounds and 15 Yachtsman pounds.

5. 5

Measure nylon anchor chain link diameters with a measuring tape. A small boat from 20 to 25 feet long should have a nylon chain link diameter of 7/16-inch. A mid-size boat of 36 to 40 feet in length requires a 9/16-inch diameter nylon chain link. A larger vessel which is 51 to 60 feet long would need a nylon chain link diameter of 3/4-inch.

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