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Cracked seam repair

Those tips from John are very good.

I have only rarely used the plastic bag method because it requires a relatively large mass of epoxy, and about half the uses, it overheats and "goes off." I usually use small batches and deliver the mix to the fillet area in dabs. Then I follow up with a double gloved finger or thumb to smooth things out. The mix being already spread out, it hardly ever goes exothermic and overheats.

OTOH, if faced with a large or very long fillet, I would definitely use the bag technique, but would shift to a slower hardener to prevent the mix from going off. Most of the time, I am working in a colder space, 60 F or colder, and must use fast hardener.
 
Another FYI re Tahe kayaks ...
Today I lost a fitting that holds the deck lines to the deck. The other fittings have a dab of gelcoat on the end of the bolt.

So it wouldn't hurt to check your deck fittings if you own a Tahe.

I think I'll take all mine apart and loktite them properly.
 
Almost started a new thread so I wouldn't be so embarrassed about how long it takes me to get stuff done. I'm taking advantage of Rod's repair course this coming weekend and will be getting back to work on this seam repair. I've scraped all the old gel coat off the seam now and given it a quick sanding in preparation for the course. Only found one more void on the bow. Looking forward to the course.
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Doug
 
Moving forward with this repair now. I got the seam area sanded down with 80 grit and then 100 grit and masked it off for the seam tape.
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I then laid the tape in place and and added the polyester resin till it was wetted out completely. (the white area is not starved glass, it is the original glass where I've sanded all the gel coat off)
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The resin was tacking up like it should and hardened overnight. Was feeling pretty good about it until I tested the bond. I was able to use a knife and pop up an end and then peel the tape off. ?????
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So......wondering why? I'm guessing my prep was flawed in some way? Like I said, I sanded it down to 100 grit and then wiped everything down with acetone prior to taping. Any advice appreciated. (LAM is anxious to get her ride back :oops:)
Doug
 
There's no chance the boat was originally built with epoxy, is there?
 
Moving forward with this repair now. I got the seam area sanded down with 80 grit and then 100 grit and masked it off for the seam tape.

I then laid the tape in place and and added the polyester resin till it was wetted out completely. (the white area is not starved glass, it is the original glass where I've sanded all the gel coat off)
The resin was tacking up like it should and hardened overnight. Was feeling pretty good about it until I tested the bond. I was able to use a knife and pop up an end and then peel the tape off. ????? Any advice appreciated. (LAM is anxious to get her ride back :oops:)
Doug
Your prep work looks excellent; how disappointing that the polyester didn't adhere. It's a very good thing that you tested and peeled the tape. :thumbsup: :thumbsup: :thumbsup:
There was no trace of silicone sealant that had been put on to stop the leaks at an earlier time? Or wax with silicone?
Make sure the surfaces are 'chemically clean' before sanding.
I wouldn't sand any finer than 60 or 80 grit.
And, I would use epoxy for any glass repairs. I think it bonds better than polyester, and I am much more familiar with it. Gelcoat and paint both stick well to epoxy/glass, so finishing is not a problem. Do a quick test to make sure your tape will wet out properly with epoxy.
 
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Thanks guys.
CPS- how would I tell if it was epoxy or polyester. These weren’t expensively built boats to start with so I’m assuming polyester.
John, I can’t see that there would have been any traces of silicon or wax after sanding and wiping with acetone. Should I be washing with a soap and water first to clean it? The reason I didn’t use epoxy was that from what I’ve heard and read I thought gel coat didn’t adhere to epoxy well. Gel coat being polyester it should work best with the polyester resin I thought.
Doug
 
Gelcoat and epoxy: The repairs I've done have usually involved gelcoat over an epoxy hull repair to a fairly small area, but I've never had problems with gelcoat bonding to cured (washed and sanded) epoxy. For something like your seam tape, I'd cover it with tinted epoxy slightly thickened with silica anti-sag(Cab-O-Sil), or just thickened epoxy and paint. But gelcoat would work, too.
https://www.epoxyworks.com/index.php/applying-polyester-gelcoat-over-epoxy/
https://www.epoxyworks.com/index.php/polyester-gelcoat-over-epoxy/
A good mechanical key is essential, IMO - so plenty of scratches and coarse sanding marks are not a bad thing.
For removing silicone, I'd use a silicone remover- available in spray cans from auto body supply houses. A lot of waxes and 'gel-coat renew' products contain silicones. And boats can have traces of mold release on the smooth surfaces, and contaminants from vacuum bagging on the inside of the hull. Sanding can drive those contaminants into the surface, so I usually start with a good (quick) chemical cleaning (depending on the surface....you don't want to dissolve paint or varnish!).
 
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I’m thinking this is the stuff you’re talking about John? Says it is safe for automotive paint, vinyl and glass surfaces. Assuming it’ll be fine for gel coat/fibreglass? What could go wrong, right?
 

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I’m thinking this is the stuff you’re talking about John? Says it is safe for automotive paint, vinyl and glass surfaces. Assuming it’ll be fine for gel coat/fibreglass? What could go wrong, right?
That should do the job.
This is what I've been using since my 'autobody and paint' guy slid it across the counter and said: "Use this!" some years ago.
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So, I made two more attempts using polyester resin. Sanded both sides down with 80 grit, cleaned with the above cleaner and wiped down with acetone......and had the same thing happen both times.....the tape would peel off. Yesterday I cleaned it up again and used West System epoxy this time. While it was still green I added a second coat of epoxy to fill the glass weave. Checked it this morning and it looks stuck this time. Big relief! :thumbsup: Decided I'll end up painting the seam instead of gel coat so picked up some Interlux for the job. Will do the opposite side of the hull tomorrow. Good to be moving forward with this....LAM is getting a little antsy. I found an old review online of the Tahe from Sea Kayaker magazine that included basic build specs. It did say there was an optional build using epoxy resin, but maybe I misinterpreted it as them using epoxy with their carbon/kevlar layups, and LAM's boat is not either.
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Doug
 
Here's the build sheet/review from SK if anyone's interested.
 

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If your Kayak does not have bulkheads I would add them.
The safety issue is a big wave could implode the hull and split it down the seam.
Maybe add reinforcement plates on the inside of the seam - kinda like canoe ribs.
 
Hi Roy, the kayak does have front and rear bulkheads.
I got the seams on both sides glassed and trimmed and then sanded. Masked everything off again (going to by stock in a tape company :rolleyes: ) and got two coats of Interlux primer on the seams. I'll give that a light sanding tomorrow and get the top coat on in the next couple of days. The Interlux primer flows out really nicely for a smooth finish.
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Getting close.
Doug
 
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