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Boat Covers that Work


Use these tips to select a boat cover that stands up to the rigors of highway speeds.

When it comes to trailerable boat covers, the F Factors will be what differentiate a common blue tarp from a custom cover for your rig: fit, fabric, and features. For mere storage, a properly supported and secured plastic tarp may be all you need to shield your boat from the elements. But anyone who’s ever attempted to use a cheap blue tarp to protect a pickup truck loaded with household goods — or shared the freeway with someone attempting the same — knows this can quickly turn into a mess, usually shortly after the vehicle reaches cruising speed. Remember, the threshold for “hurricane-force” winds starts at just 65 mph, the speed limit on many American highways. If you wouldn’t expect your cover to be in one piece after a hurricane blows through, why should it hold up to a jaunt down the interstate?

Denier is a unit of measure for the linear mass density of fibers, defined as the mass in grams per 9,000 meters. A single strand of silk is approximately 1 denier; a 9,000-meter strand of silk weighs about 1 gram.

The Fit Factor

“In the boat-cover industry, there are three classes of boat covers, based primarily on fit,” says Dave Karpinski of Taylor Made Products. “Universal, semicustom, and custom. Universal or ‘storage’ covers are cut with a more generous fit to remain generic, are usually offered in two-foot increments, and one model is intended for both sterndrive and outboard boats.” For example, one cover is designed to protect boats ranging from 16 to 18 feet in length, another for craft from 20 to 22 feet. Universal boat covers “tend to be big and baggy,” he says, to accommodate the greatest number of boat models and such options as windshields, outboard cowlings, seat configurations, and bow-mounted motors. Because of the loose fit, universal covers aren’t generally suitable for trailering use.

Semicustom covers are designed for specific hull designs and fit tighter, and when they’re properly secured, they can be suitable for trailering. For example, Taylor Made offers semicustom covers in one-foot centerline length increments for 30 different trailerable boat designs, with multiple widths in each length category to fit a majority of applications. Generally, the more specific the fit to your boat, the higher the price. You’ll also pay more for stronger, longer-lasting materials.

Custom covers made to withstand the rigors of trailering are tailored for a particular boat model to give a tight, custom fit. They are patterned to fit and reinforced where needed to accommodate the windshield, seat, and cleat locations, bow-mounted motors, and any other accessories on a particular boat. A custom cover, due to the less generic fit, has less excess fabric. If your knuckles don’t turn white with the effort of putting on a trailerable boat cover, maybe it’s not tight enough!

Boat covers that don’t fit tight enough can allow air to get under the top during towing and cause it to pull free or fail at weak points. Posts used to support a cover to shed water while the boat is in storage, such as the one above, aren’t recommended for use while towing because they often work free and leave the top loose.

Fabric Matters

Cotton has been replaced by polyesters, which are lighter, stronger, and wear longer, as well as by such acrylics as Sunbrella. Fabric is what determines the price of boat covers, and Sunbrella is often used in semicustom and custom covers; polyester is used for everything from universal to custom boat tops. The denier, or weight of the fabric, determines the differences in polyester quality and cost. Universal covers are made of polyester typically in the 150-denier range, while semicustom and custom tops are usually constructed of 300 up to 600 denier polyester.

A cover is only as good as its weakest point. With cotton-blend covers, it was the material itself that often degraded and failed first. That’s changed with polyester and acrylic fabrics, which hold up well and have allowed concentration on such features as seams and straps to complement the quality of the cover material.

Features Rule

To make a cover bulletproof on the road, make sure it has the following features, in addition to a closer fit to the boat’s contours and accessories:

Reinforcement patches:

Sew these into the underside of the cover in places prone to premature wear from the rigors of the road, including areas where the material comes into contact with cleats, windshields, trolling motors, and boarding ladders.

Seam strength:

Quality boat covers may feature several folds of the fabric and multiple lines of stitching to keep panel connections secure.


Facing the top fold of the seams aft, for instance, lets them naturally shed wind and water like shingles on a roof.


These secure the cover to the trailer; most manufacturers recommend using adjustable-buckled webbing attached to the cover’s straps and securing the cover to the trailer frame rather than to the boat. Some boaters prefer the snug fit that results by connecting corresponding straps on each side of the boat with webbing that runs under the hull at intervals down the length of the craft. Securing the cover to the trailer saves crawling around under the boat every time you put the cover in place. It also allows you to preset the buckles to the proper length to avoid having to adjust them each time the cover is installed.

Whether you connect them to the trailer frame or to each other under the hull, it’s important to use every strap-point offered along the length of the cover to keep it secure at trailerable speeds. Failure to do so — or to overlook a small tear or weak seam — can result in quick and dramatic failure down the road.

Dan Armitage

Contributing Editor, BoatUS Magazine