How To Repair Stress Cracks In Fiberglass

Filling in the Gaps

At that place are many ways to repair cracks in fiberglass—which 1'south the best?

Stress cracks, spider cracks, and hairline cracks in the decks of older boats are, of course, not rare. Sometimes, they're merely cosmetic, meaning they don't penetrate the gelcoat. Sometimes, they go deeper and threaten an underlying laminate, which in many cases is cored. Because the latter scenario may evolve into a very expensive proposition (replacing coring materials in an existing deck is a messy, pricey task all-time left to the professionals at your yard), it makes sense to address all suspicious-looking cracks on board your boat every bit shortly as possible, especially in areas that feel a little spongy (probably due to coring issues) when stepped on.

Before you brainstorm, notwithstanding, a word of alarm. There are numerous, inexpensive products on the market these days that purport to be easy fixes for hairline and other fractures in fiberglass laminates. I've personally tried two of the almost pop of the lot—MagicEzy Hairline Fix and Captain Tolley'due south Creeping Crack Cure—and, although certainly piece of cake to use, neither one comes close to existence a substitute for doing the chore the right way, as follows:

Footstep 1 Figure out what acquired the cracks to begin with. Do they emanate from a stanchion base that flexes? Practice they spread out from a radius that vibrates or twists in a seaway? Do they surround an area that feels just a lilliputian spongy, every bit already noted? Call up about it.

Step two Then toughen the laminate that contains the crack or cracks by solidifying information technology, either by thickening with more than fiberglass, replacing coring materials, or adding structure. If yous don't practice this, new cracks volition most likely appear, probably not likewise long after you've only finished fixing the old ones.

Step 3 At present, once you've removed all hardware, toerails, and other paraphernalia that may clutter or interfere, intermission out a Dremel tool with a conical fleck. Then follow each split fissure with the Dremel as if you were wielding a pencil. Utilise the highest speed possible, since low speeds may cause the flake to catch or swerve damagingly from your intended path. And let the Dremel practise the work—several shallow passes will produce a cleaner, more than authentic chore than going for a unmarried, deep, forced march.

Footstep 4 As presently as the crack has been channeled out, wipe it clean with a solvent like acetone and, using a plastic putty pocketknife, flush-fill it with gelcoat matched to the color of the surrounding expanse (if the channel isn't too deep); polyester filler (if the channel is of medium depth); or polyester resin and fiberglass strands (if the channel is very deep and wide). Information technology'southward a expert idea, by the way, to mix up a couple of small batches of gelcoat to help you guess the color you lot need. Also, epoxy can exist used in identify of polyester in some situations, although it tends to be much harder than poly and therefore more difficult to sand smooth and finish. And don't forget to temporarily encompass all gelcoat repairs with plastic film—gelcoat does not cure thoroughly when exposed to air.

Step 5 Finishing is the last aspect of a proper gear up. When dealing with gelcoat, dry sanding followed past wet sanding, with ever more than refined, smoother grades of paper (starting with 220-grit and working your way downward to super-fine 600-grit) is appropriate, followed by a good wax or shine. When dealing with a polyester or epoxy repair, numerous cracks are unremarkably involved, and you may exist looking at a paint task of some kind in the near time to come.

This article originally appeared in the December 2022 issue of Power & Motoryacht magazine.