Canvas Repair—Seams, Zippers & Velcro


In the third and final post of our canvas repair series, we’re going to look at how to re-stitch seams, and how to replace old, failing zippers and Velcro on your boat canvas. Simple repairs like these can keep your cover in good working order for years to come. Be sure to catch up on the first two parts of this series where we discussed patching rips and tears, and replacing snaps and grommets.


Thread rots faster in the sun than most cover fabrics do, so you can often get several more years out of your canvas by re-stitching the seams when they fail. When thread gets old and rotted, it will start to disintegrate. A good way to test the strength of your stitching, is to gently pick at the thread with your finger. If the thread starts to fall apart at your touch, you should re-stitch.

If your cover is fairly new and you want to really prolong its life, you can use a lifetime thread like Tenara to re-stitch your seams. Tenara can be tricky to sew with, but it will likely outlast your canvas. In most cases, a UV treated V-92 Polyester thread will be a great choice. This thread is the standard for outdoor covers and is treated to be resistant to UV rays.

When you go to re-sew the seams and hems, you don’t need to rip out the old thread, just sew right over it. Since you will have a large bulk of fabric to maneuver around your sewing machine, be careful to not get extra fabric caught under the foot.


If your covers and enclosures have zippers that are failing, they can also be replaced to extend the life of the cover. Zippers will rot over time with strong exposure to UV rays. A zipper is at the end of its life when it starts to fall apart or frequently pops open on its own.

If the zipper is easily removable, rip out the seams holding the zipper and sew a new zipper in its place. If the zipper is in an assembly where it is surrounded by binding and other elements that would require a lot of deconstruction, just cut the zipper out as close to the canvas as possible, and then install a new one.


Velcro can be a really handy fastener around boats, but if not properly protected from the sun, it can quickly fail. If you have Velcro that is just not sticky anymore it can easily be replaced. Rip out the seams holding the Velcro to the canvas. Then you can sew new hook and loop in its place.

The backside of Velcro should always be protected from the sun. If your Velcro was not backed with canvas, we recommend adding a canvas flap for the hook and loop when you replace it. Just cut a piece of canvas a little bigger than the Velcro, and sew the Velcro to it. Then sew the canvas to the rest of the cover. This will prolong the life of the hook and loop.

This concludes our canvas repair series. Did we cover your questions? If you have questions on your canvas repair job, ask us in the comments and we’ll do our best to help!

You can find replacement thread, zippers and marine hook and loop and so much more for your canvas repairs at


    What type of thread do I use to see Velcro to canvas.

    • Nikki said:

      Hi Muriel,
      You’ll want to use a UV polyester thread for sewing Velcro to canvas. If you have a home sewing machine, use a size V-69 or if you have a heavy-duty sewing machine, like our Ultrafeed, use a size V-92.

      You can see our thread selection here:

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