Striving for a Stronger Boat Cleat

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Ralph Naranjo

Casting metal parts has been a technology in use for at least 6,000 years, and it remains the preferred approach when it comes to manufacturing sailboat cleats. Modern investment casting yields smooth symmetrical surfaces in need of less polishing. The approach can be used with zinc, aluminum, bronze, and stainless steel. Zinc, though often found chrome-plated on low-end powerboats, is too weak a metal to be used for cleats on a sailboat. Aluminum alloys are light and relatively strong as long as the casting process has kept void (air bubble) content to the barest minimum possible.

One of the biggest challenges with aluminum alloy cleats is their galvanic interaction with the stainless-steel bolts that secure them to the deck. Bronze and 316 stainless steel castings are heavy, but they are also stronger and less prone to corrosion issues. The shape of a cleat carries real significance in a variety of ways. The first and most important is how the configuration locks a line in place yet still allows a crew member to control the easing or snubbing process.

Cleats with abnormally long horns and two bolt attachment points allow more line to be wrapped around the appendage, but these long-horn cleats also present increased leverage on the base and more vulnerable end points.

The four-bolt open pattern of Herreshoff-style cleats affords greater support, and their shorter horns are less vulnerable. Some cleats come with an in-line, three-bolt pattern that offers significant strength in one direction but very little on an angle thats perpendicular to the bolt alignment. All cleats rely on good engineering practices when it comes to how they are installed.

Those retrofitting or upgrading their boats deck cleats can greatly improve the installation with a little attention given to topping and backing plates.

The former is a carefully cut and painted piece of G-10, or homemade FRP layup comprising three to five units of woven roving and mat laid up on a smooth waxed surface. The solid glass laminate ends up about a quarter-inch thick, and using a cardboard template, is cut to well exceed the cleats bolt pattern footprint.

The exact shape of these topping and backing plates depends upon available space and deck shape, but the underlying principal is to provide a load-spreading capacity both above deck and below. The topping and backing plate are best bonded in place with a gap-filling epoxy putty prior to cleat attachment.

When the epoxy putty has cured, the cleat can be fitted, holes drilled and a sealant used on the fasteners during the installation. If a raw balsa or low-density foam core is exposed in the newly drilled holes, the extra time spent hooking out a half-inch perimeter around the hole and filling it with epoxy putty will pay off in the long run. Be sure to plug or seal the bottom of the hole before filling the holes with epoxy putty. Once it cures, re-drill the holes and install the cleat.

For related articles: see

Practical Sailor Takes a Close Look at the State of Boat Cleats

Trouble Free Deck Hardware Installation

A Better Way to To Mount Deck Hardware

How Big Does a Backing Plate Need to Be?

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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