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ContinuousWave: Whaler Repairs/Mods
epoxy and gelcote repairs
|Author||Topic: epoxy and gelcote repairs|
posted 09-12-2002 12:17 PM ET (US)
i want to open and fill some holes with epoxy and then go over them with gelcoat. the west marine near me only has 3m and evercoat brands of gelcoat and they both say NOT to put it on top of epoxy. i've read through the "Minor Repairs with Epoxy" peice many times and there is no mention of that there. what should i do?
posted 09-12-2002 01:15 PM ET (US)
Forget using epoxy, and if the repair is large, use general purpose resin (per BW's instructions). BW's hull repair instructions do not use epoxy and recommend general purpose resin instead. They say:
"For holes up to 3/16" in diameter, they can be simply filled with gelcoat resin and chopped fibers, or resin alone if it doesn't run out" Paste gelcoat is now available for these kinds of repairs and filling screw holes.
"Larger punctures, or holes up to the diameter of a dime, should be repaired as in the Structural Repair Instructions" (to lengthy to repeat here) Quickly, these involve scraping out a foam dish under the skin edge, grinding the glass edge to a tapered knife edge, filling with chopped fiber impregnated polyester resin mash, grinding down flush, and then painting on a layer of gelcoat. On really big jobs, new foam blocks have to be inserted to restore any damaged or missing foam.
posted 09-12-2002 03:16 PM ET (US)
nice. i did see the paste and regular gelcoat. that's going to make it a lot easier. thanks!
posted 09-12-2002 04:07 PM ET (US)
is gelcoat paste strong?
posted 09-12-2002 04:19 PM ET (US)
WADR (with all due respect) and I have a fair amount for Larry's opinions as well as for Tom Clark's, who posted a similar statement about epoxy and resin a couple of days ago-
There are a number of us who do and have repaired at least small holes (and some large repairs by DIVE1 if I'm not mistaken) using West Systems epoxy then gelcoating over the cured epoxy with both paste and liquid gelcoat successfully. I understand it is important to remove the amine blush from the cured epoxy before applying the gelcoat or there may be an adhesion problem.
I regularly repair my Outrage 22 this way, from countersunk screw holes maybe 3/8" to 1/2" in diameter up to areas where I have removed rodholders from the transom, maybe 2 1/2" in diameter. The repairs are solid and permanent. When I want to really bear down on the final finishing, I can and have made the repairs impossible to find.
So I wouldn't forget using epoxy across the board, and if I were you, I would get my hands on some Spectrum BW color-matched gelcoat paste.
posted 09-12-2002 05:55 PM ET (US)
Thanks for the clarification, John. And I should add that it's not that epoxy doesn't work, it's just that I got the impression from the BW instructions that it's not necessary to use this more difficult and expensive material. More like overkill.
I assume that West's epoxy is actually a tougher material than polyester resin. So it certainly does the job, as indicated. Don't know if BW uses epoxy in the construction of their boats.
posted 09-12-2002 08:48 PM ET (US)
Top coating epoxy surfaces with gelcoat resins requires attention to preparation, but it is easily done and works well.
One feature of epoxy I like (besides its higher strength) is the ability to mix up batches that will cure to complete hardness in a known amount of time.
Gelcoat resin is catalyzed to induce curing, and it often seems like the mixing ratios are hard to judge. You add a drop or two of MEK catalyst to a big glob of resin and hope you get a cure in a reasonable amount of time.
With WEST System products like their calibrated pumps, you can mix batches of epoxy with known cure rates time after time.
I find it handy to have WEST System epoxy around the house, too. I just mixed a small batch to glue a door back together after it suffered some damage at the hinges and pivot points. When you glue two pieces of wood together with WEST System epoxy, they are not coming apart at the glue joint.
posted 09-12-2002 09:20 PM ET (US)
posted 09-16-2002 08:12 PM ET (US)
RULE OF THUMB..Epoxy over polyester--NEVER vice versa.
posted 09-17-2002 03:55 PM ET (US)
For smaller repairs such as screw holes, I'd suggest filling the hole with a UV cure polyester/chopped fiber resin like Solarez (avaialable at any surf shop or on the net). Then, finish with Spectrum color matched gelcoat. The UV cure sets up hard and fast in direct sun light, and doesn't require any mixing. It also has a nice, stiff consistency so it won't run out of holes in vertical surfaces. Do the repairs in the shade, then simply roll your boat into the sun to cure them.
posted 09-18-2002 11:38 AM ET (US)
posted 09-21-2002 08:23 PM ET (US)
I just bought some supplies from Minicraft in Florida. The have BW colors. The technical people were very helpful.
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