The chain primarily contributes additional weight. The anchor line and metal chain together are called the anchor rode.
The best material to use for anchor line is nylon. Nylon is a synthetic fiber or fabric made from petroleum. It is popular in boating because it is strong and elastic, relatively inexpensive and resistant to wear and tear. When a wave rolls toward a boat anchored with nylon line, the nylon will stretch like a rubber band, absorbing shock and preventing destructive jerking. Nylon rope for anchor line can be purchased in a couple different configurations, three-strand and double braid. Three-strand nylon rope, which is preferred by most serious cruisers, offers greater elasticity at a lower cost and resistance to abrasion.
Three-strand nylon for anchoring should be medium lay, which has more twists per foot than soft lay. This is particularly important where windlass is concerned, as soft lay strands can untwist and separate, potentially causing harm to the equipment. Soft lay also runs the risk of snagging and collecting abrasions as it runs along the bottom. Three-strand nylon anchor line can eventually become hardened from saltwater saturation or stiffened by constant outdoor exposure, making it difficult to work with. If this should happen, it is best to simply replace the line. Braided nylon is more flexible than three-strand nylon, making it the better choice for when the rode is fed through a deck pipe for stowage. Although it is stronger and generally easier to work with, it is important to note that braided nylon anchor line does have a tendency to deteriorate from tears and abrasions.
Whatever choice a consumer makes, he or she must also decide on the size of the anchor line purchased. A good rule of thumb is to purchase an eighth of an inch of rope diameter for every nine feet of boat length. To determine the needed length of an anchor rode, a consumer should multiply the depth of the deepest water he or she expects the anchor to drop, then multiple that by eight. For example, to drop anchor at the deepest depth of twenty-five feet, a boat owner should buy two hundred feet of rope.