Most well-made cleats fit the bill, but beware.

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In the 90s, the Boat US Foundation performed a study of deck cleat strength. Testing was performed using 6-inch cleats of a number of materials and designs, which were pulled from several directions. The standard vendor recommendation is 1/16-inch of line size for each inch of cleat, so these cleats are recommended for use with 3/8-inch line (breaking strength 4,200 pounds, working load limit 525 pounds). All but the nylon cleat had working load limits (assume 4:1 safety factor for metals) greater than nylon rope. Most were nearly as strong as the rope, but only two were stronger than the rope in all directions. We can expect strength to go up roughly as the square of size, roughly matching rope strength as we go. Only a few broken cleats were noted among the boats damaged by Hurricane Irma. More commonly, the cleats pulled out of the deck.

Obviously, cleats need a firm backing. A strong, well-engineered deck helps, but backing plates are essential (see How Big Does a Backing Plate Need to Be? PS August 2016).

Watch the angle formed when the line goes through the chock. You may not be able reduce the downward angle, but any pressure against sharp edges will weaken the line by 20 to 50 percent. Avoid sharp turns, which forces fibers on the outside of the turn to carry most of the load. Try to keep the runs straight, and pad the turns with heavy chafe gear.

Bottom line. Cleats and chocks must be sized for the required line size, which for storm-mooring a 35-foot yacht requires 7/8-inch line and 14-inch cleats. However, it is a rare 35-foot boat that has cleats over 10 inches. This is a challenge.

For the full report on cleat strength from the BoatUS Foundation, see https://www.boatus.org/findings/16/.

Darrell Nicholson, editor of Practical Sailor, grew up boating on Miami’s Biscayne Bay on everything from prams to Morgan ketches. Two years out of Emory University, after a brief stint as a sportswriter, he set out from Miami aboard a 60-year-old wooden William Atkin ketch named Tosca. For 10 years, he and writer-photographer Theresa Gibbons explored the Caribbean, crossed the Pacific, and cruised Southeast Asia aboard Tosca, working along the way as journalists and documenting their adventures for various travel and sailing publications, including Cruising World, Sail, Sailing, Cruising Helmsman, and Sailing World. Upon his return to land life, Darrell became the associate editor, then senior editor at Cruising World magazine, where he worked for five years. Before taking on the editor’s position at Practical Sailor, Darrell was the editor of Offshore magazine, a boating-lifestyle magazine serving the New England area. Darrell has won multiple awards from Boating Writer’s International, including the Monk Farnham award for editorial excellence. He holds a U.S. Coast Guard 100-ton Master license and has worked as a harbor pilot and skippered a variety of commercial charter boats.

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