Inspecting Your Marine Canvas

With summer around the corner, now is a good time to check out your boat's canvas and make sure it's ready for the water. There's nothing as aggravating as having a major failure of some part of your boat while underway, and that includes your marine canvas.

Here's a few steps you can take to make sure your bimini top, dodger, boat cover, or clear vinyl enclosure is seaworthy.

U.S. Marine Canvas can take care of any of the following repairs or maintenance issues you may have. Call or text us at 386-983-2470 or email me at This email address is being protected from spambots. You need JavaScript enabled to view it. for service.

Check the Stitching

Most marine canvas is not sewn with thread that is truly ultra-violet (UV) resistant. The most common threads used by canvas shops are treated with UV inhibitors that leach or wash out due to heavy weather exposure.

The best way to check the stitching is to try pulling the seams apart by hand. You can also try pulling the zippers away from the fabric of your enclosure curtains. And don't forget to check the pockets that hold your bimini top to your frame, these usually are the first seams to fall apart.

If any of the stitching or canvas is coming loose, get your canvas re-stitched before hitting the water. Make sure your top is re-stitched with a PTFEÂ thread, which is inherently UV resistant and will usually last the life of your canvas. Some trade names to look for are Tenara, SolarFix, and Solar Thread.


Zippers, notorious for their short life span, are usually the highest maintenance item in marine canvas. YKK now adds UV inhibitors to their zippers during manufacturing, resulting in longer life. Black zippers generally last longer than white zippers because the carbon added to them for color makes them highly resistant to the suns rays.

To test your zippers, run your fingernail along the zipper teeth. If you see any flaking or gritty substance on your finger, the zipper needs to be replaced.

Check your zipper slides as well. They should move freely along the length of the zipper with little resistance. Corroded or frozen zipper slides need to be replaced. Sticky zippers can benefit from lubricants like petroleum jelly or Star Brite Snap and Zipper Lubricant.

Never use silicone based lubricants on your plastic zippers. They may temporarily make it easier to zip your canvas shut, but silicone breaks down the plastic teeth and shortens the life of your zippers drastically.


Woven marine canvas fabrics like Sunbrella are water-resistant when new, not waterproof. After a few seasons in the sun, the water-resistant barrier breaks down and water can soak through your bimini top or boat cover.

If water is coming through your top or cover, it's time to waterproof your canvas. Since Sunbrella and other woven synthetics resist silicone, only waterproofing applications designed for Sunbrella should be used. The local canvas shop can usually handle this project best. For do-it-yourself, try 303 High Tech fabric Guard or Star Brite Waterproofing.

Also check the strength of your fabric by pinching two sections of your canvas and then try ripping them like you would a piece of paper. If your canvas tears even slightly, you need new canvas, patching it is no longer an option.

Clear Vinyl

The clear vinyl curtains on your boat should not only protect you from the weather, but give you good visibility while underway. The sun is the biggest enemy of your clear vinyl, as it leaches out the plasticizers that keep it clear and flexible, which also results in shrinkage over the years.

Any clear vinyl that is browned or cracked is irreparable. Permanently damaged glass can sometimes be replaced while leaving the canvas trim in place, saving you time and money. Remember that replacing shrunken clear vinyl with new vinyl will result in even tighter curtains as the new vinyl ages and shrinks.

If your glass is cloudy or hazed, it may just be moisture trapped in the glass (which is more porous than you think). To correct this, leave your canvas up for several days with good sun exposure, and do not roll it up during this time. Never leave your wet clear vinyl rolled up for very long as the concentrated heat of the sun's rays can drive the moisture into your vinyl.

Small scratches and imperfections can be treated with polishers specially designed for clear vinyl, such as Meguiars or similar products. Most of these polishes also help restore the plasticizers that have leached out over time.

For Strataglass or O'Sea vinyls, IMAR is the recommended cleaner and this can also be used for all of your clear vinyl weather curtains.

Snaps and Hardware

Look at all of your snaps and other fasteners holding your canvas to the boat. Keeping them lubricated with petroleum jelly or Star Brite Snap and Zipper Lubricant will help them last longer and function properly.

Any damaged hardware should be replaced immediately as the failure of one fastener puts extra stress on the fasteners adjacent to it. You'll probably have to go to a local marine canvas shop to fix these items since special tools may be required to repair them properly.

If you need any of these repairs handled professionally and quickly, call or text us at 386-983-2470 or email me at This email address is being protected from spambots. You need JavaScript enabled to view it. for service.

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