Repairing a Damaged Fiberglass Sea Kayak Part 3: Back and Fill and Patch Again

Above: Deep damage to the gunwale of a Romany Explorer. Note the differences between damage to the gelcoat and damage to the fiberglass. Doubleclick this and all other images to enlarge.

During the rasping and grinding stage (step 1), you need to make make a hole in the side of your sea kayak quite a lot larger than the gash and crazing shown above. You'll need to grind off a lot more gelcoat, and cut away more fiberglass, than you see damaged above.

So below, in photo 2, we see the result of the handiwork that followed: back-patching a nice clean hole that dispatches with the ugly above:

Doubleclick this and all other images to enlarge.

Note that in the process we needed to abrade the hull as far as the boat's model name (look at the letters L, O, R). In doing so we deliberately ground off a ring of gelgoat larger than the backpatched hole, in anticipation of the outside fiberglass patch to follow.

So what's a backpatch? A single layer of new fiberglass epoxied against the inside of a hole in a fiberglass sea kayak.

To keep fiberglass and epoxy in place while the epoxy cures, you'll need to apply pressure to the fiberglass with piece of a plastic milk jug you use as a form. You can get the form stay in place by wedging a piece of foam, wrapped in plastic, against the sectionof milk jug.

Below, in photo 3, you'll the step after the backpatch cures.

Here Brian Nystrom prepares to cut another fiberglass patch (the first of several) to fit the outside perimeter of the hole. Because fiberglass doesn't adhere well to gelcoat, Brian will cut the fiberglass so that it is just slightly smaller than the hole in photo 2 - look for the dark outline of the backpatch, behind the fiberglass Brian is outlining in pencil.

That ragged line extending away from Brian's index finger, by the way, is not cracked gelcoat but a stray fiberglass thread.

Doubleclick this and all other images to enlarge. Brian Nystrom photos

To do much of the work above, you'll need some equipment.

Here's a partial list:

You'll need a random orbital sander. Porter-Cable makes a good one for $53.00.

Buy hook and loop sanding discs in grits from 80 up to 220, jumping 40 grits at a time (80 and 120, etc.). Just don't buy the sanding discs from your local Home Depot.

You can get much better deals on mail-order: $15.00 for a box of 50 discs, for example.

Porter Cable's random orbital hook-and-loop sander:

Also, fiberglass resins give off nasty fumes, making you vulnerable to brain cell loss if you work indoors. DO NOT use a dust mask. You need protection from resin's fumes. Best bet is to wear a VOC respirator.

VOC respirators (don't apply paint or varnish or do a lot of sanding unless you're wearing one!):

To read the rest of the series, use these links:
Intro
Part 1
Part 2
Part 3
Part 4Part 5
Part 6