Advice - cracks and hairline cracks in gelcoat

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DiscoKayak
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Advice - cracks and hairline cracks in gelcoat

Post by DiscoKayak » Sun Dec 23, 2018 9:19 pm

Hi there,

Yesterday, I was out paddling close to a rocky coastline, and at one point the hull of my kayak scraped a rock. Inspected the damage afterwards and found a few scrapes and a small crack in the gelcoat + a some fairly small hairline cracks going out from where I bumped against the rock - I think it is what some might call a "star crack". I imagine that I, at some point, will have to take care of the damage, but is it something I should do something about very soon? And would it be unwise to go paddling until it has been repaired?

I hope you can offer me some advice.

Btw. the boat is carbon kevlar (if it matters) and I added some photos. It was a bit hard to get a proper photo of the hairline cracks.

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Chris Bolton
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Re: Advice - cracks and hairline cracks in gelcoat

Post by Chris Bolton » Sun Dec 23, 2018 10:00 pm

Hi, and welcome to UKRGB

That's quite minor, and it wouldn't put me off using the boat at all. It's said that there are two kinds of sea kayak, those with scratches and minor cracks, and those that don't get paddled.

If you want to fix it, there's some advice in this thread. Take note of the post from 'Jim' in that thread - he has worked as a professional laminator.

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MYSSAK
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Re: Advice - cracks and hairline cracks in gelcoat

Post by MYSSAK » Sun Dec 23, 2018 10:38 pm

I took this photo of my kayak sometimes in early spring. Those scratches didn’t stopped me using it at all. In contrary I don’t worry at all if I add additional scratch to the hull.
Having said that, I think it is very likely I will finally do do some gelcoat repair in 2019. Unless I am distracted by paddling of course.
Michal
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Douglas Wilcox
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Re: Advice - cracks and hairline cracks in gelcoat

Post by Douglas Wilcox » Mon Dec 24, 2018 5:35 pm

Greetings Disco,

that is good proportionate advice from Chris and Michal :o) . My kayaks looks much more like Michal's than yours. However, there is something that bothers me about your kayak gel coat in the second photo. Something I have never seen in any of my kayaks. It's not the straight abrasion marks or the hair line cracks. It shows up best in photo with the reflected highlights. There are strange, very fine, circular swirl marks on the gel coat. For the life of me I can't imagine what caused them :o) :o)

I wish you many happy days in your kayak, and remember, the first scratch is always the deepest.

Douglas.

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Jim
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Re: Advice - cracks and hairline cracks in gelcoat

Post by Jim » Mon Dec 24, 2018 9:15 pm

I might check if any water comes out of the crack perpendicular to the scratches, and if not leave it alone for now. The scratches would mostly buff out, although you would need to wet and dry pretty deep and I don't see a need to.

Today I crashed my river racer (I was aiming for the sea but missed and hit a rock wall before I got there, I swam into the sea though) and did a bit more damage than that - I can see I have scraped through the carbon kevlar on the bow for about 4 inches (will need a patch) and it looks like there might be a couple of inch long cracks in the stern where I tapped the tail on a rock a few metres earlier, but under the middle of the hull where I bounced over a couple of rocks (I was a little off my intended route) there is not a mark to be seen. Carbon Kevlar is pretty tough, but because iot is woven, if you do split it, the crack will often run straight for a few inches along the weft or weave. It will give me something to do tomorrow afternoon.... ;)

I reckon the swirl marks are from a sea monster, maybe some kind of giant lamprey?
(they are actually evidence of probably a mechanical polisher being used either on the hull, or on the mould. Possibly they are actually swirls from the release wax on the mould (it is applied in a circular motion), but I've always thought it buffs off smooth, so I'm more inclined to think it is from polishing the mould. As Douglas notes, they are only visible with a very specific light direction, and I'll bet you can't feel them - not did the mould builder when he decided the mould was smooth enough! It is amazing how something that feels smooth can actually look quite rough in the right conditions, or under a microscope).

DiscoKayak
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Re: Advice - cracks and hairline cracks in gelcoat

Post by DiscoKayak » Sun Dec 30, 2018 1:45 pm

Hi,

Got caught up in a lot of christmas family events, so haven't had time to sit down and reply. As you suggest, I will leave the scratches alone. In fact, they look quite minor now, and as you mentioned it actually looks like the boat has been paddled ;-) I guess the first scratch is indeed the deepest!

I hadn't noticed the swirl marks you mention, and they aren't detectable when running a hand across the mould, but it is an interesting observation.

Thanks for the help and happy New Year to you all!

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Re: Advice - cracks and hairline cracks in gelcoat

Post by SJD » Mon Dec 31, 2018 8:47 pm

The scrape is not much to worry about. I would keep an eye on the cracks watching for spreading/lengthening. I assume you checked the inside laminate for cracks to confirm that it is only gelcoat damage. I would add that if you foresee selling the kayak in the future it may payoff to repair the damage area.

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Re: Advice - cracks and hairline cracks in gelcoat

Post by Ceegee » Tue Jan 01, 2019 1:19 am

Douglas Wilcox wrote:
Mon Dec 24, 2018 5:35 pm
There are strange, very fine, circular swirl marks on the gel coat. For the life of me I can't imagine what caused them :o) :o)
Hi Douglas, it is just an optical effect. Micro scratches (and I mean MICRO!!! - all surfaces have them) when lit from a certain angle show up tangential to the light source. The scratches are random, present in all directions but only the ones tangential to the light reflect, and thus show up.
Cheers,
Steve C. G.

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Re: Advice - cracks and hairline cracks in gelcoat

Post by pathbrae » Tue Jan 01, 2019 9:13 am

I've only ever seen these strange swirl marks on very new boats, they seem to get worse for a bit then disappear after a few outings although they'll sometimes return just before I sell a boat. I've also noticed them on the occasional new car for a month or so too - and again they seem to come back just before I sell it. Very odd!
One of our neighbours cars seemed to be afflicted by them all the time - but maybe they only show up because he washes it every second day....
So much sea - so little time to see it.

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