Crack in kayak

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Thesmoothound
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Crack in kayak

Post by Thesmoothound »

Hi,
I picked up a second hand kayak back last month and all seemed OK at first. The usual scratches but nothing major. However, just got it out to give it a good clean and have just discovered a large crack around the seat area. This was covered up by seat originally which was glued down hence why I didn't see it. Have spoken to the seller and they deny all knowledge of it. Said I must have done it. 😠
Please can someone advise me if it is even worth attempting to repair it (if so, any advise) or should I just cut my losses and ditch it.
I only what to use it for a bit of fun on sunny days close to the coast line. I am not aiming to be going far out with it.
I am struggling to upload the image so if someone may be able to help I can send separately.

Thank you in advance for your advice and help.

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Ceegee
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Re: Crack in kayak

Post by Ceegee »

Just about any damage in a GRP (composite) kayak is repairable, and easily so.

The seat being glued down was probably the problem. It transfers all the stresses to the hull. Best to have a free-floating seat, attached to the cockpit rim, or maybe the side seam via bolts, with just a mini cell foam pad underneath as a cushion.

As to repairs. If you can remove the seat and clean/roughen the area (with a dremel or similar) a largeish patch of several layers of CSM, topped with a layer of glass fabric, will do the job nicely. If the crack is all the way through, on the outside channel the gelcoat with a dremel, fill the gouge with a colour matched flow coat and wet'n'dry paper it back to a smooth finish.

If you post some photos, I and others can advise.

Annoying I know, especially as the seller is passing the buck, but not a car crash.

The repairs shouldn't cost more than £25 in materials, and take an afternoon at best.
Cheers,
Steve C. G.

Thesmoothound
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Re: Crack in kayak

Post by Thesmoothound »

Hi Steve,

Thank you so much for taking the time to reply. Really appreciate it.
Good to know that it should be repairable.
Attached is the photo of the crack on the kayak. The gunk around it is the adhesive the guy used. I will obviously remove this when I do the repair. As you can see, the bottom section has pushed down, so will need to prise this back up level with the other section. I have read that I should drill a hole either end of the crack to stop it cracking any further. Is that correct?

Do you have the product in mind for the CSM and glass fabric? This is all new to me to be honest.

Hopefully from this photo, you will be able to get a better idea.

Kind regards and thanks again.

Image

pathbrae
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Re: Crack in kayak

Post by pathbrae »

What type of kayak is it? (make and model if you know it but even generically - is it a sit-in kayak with a cockpit and sptay-deck or a sit on top?) Is it plastic (RM) or composite (fiberglas / diolene / carbon etc....) and what can you see on the bottom of the hull in the area where the crack is (does it go right through or is there a double skin?)
The two holes look like drain holes - which makes me think sit-on-top)

Maybe a picture with a bit more space around the crack so we can get a sense of scale could help.
So much sea - so little time to see it.

Thesmoothound
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Re: Crack in kayak

Post by Thesmoothound »

Thanks Pathbrae.

It is a Tek Sport 285 X-T-Sea Sit On Kayak. Please see below photos from above and below.

Thank you
Image

Image

charleston14
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Re: Crack in kayak

Post by charleston14 »

Probably hdpe plastic, so might …be plastic weldable. You can buy hdpe plastic rods for this purpose but need to read up on how to do it.

But always bear in mind that it’s been structurally compromised to some degree.

Example;

Last edited by charleston14 on Mon Jun 21, 2021 5:48 pm, edited 1 time in total.

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Ceegee
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Re: Crack in kayak

Post by Ceegee »

I'm guessing its HDPE too, so my advice(for GRP) doesn't apply, as Charleston says, it's a hot welding job, still doable, but not my area of expertise. I'm sure others here can advise though.
Cheers,
Steve C. G.

Chris Bolton
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Re: Crack in kayak

Post by Chris Bolton »

The question is, to me, what's the significance of the crack and therefore, how 100% does the mend have to be. I've never had a SOT, but I assume the top and bottom mouldings are joined to make a watertight whole, with the drain holes forming a sealed route through. If water gets in through the crack while paddling, is the inside of the boat filling up? In a decked plastic kayak, you would know if it was leaking, but in a SOT maybe you'd only find out when it affected the handing. Is there a hatch?

One the left side of the photo of the cracked area, there's strip of white that looks a bit like there's plastic missing? If that's the case it makes welding it more tricky (not impossible). It would also indicate the the seat was glued down to try to seal (or hide) the crack, rather than it having cracked below the seat after it was fitted.

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P4ddy
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Re: Crack in kayak

Post by P4ddy »

I plastic welded on a high stress point on a bike fairing but just used a soldering iron and stitched it together then smoothed the join with the iron (I didn't have a proper welding tool and rods). Then for added strength I added some fiberglass (the two part in a tin type). The hardest part on yours would be pulling the dropped part up again. Lots of heat will help.

Thesmoothound
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Re: Crack in kayak

Post by Thesmoothound »

Hi. Thank you for all of your advice.
Chris Bolton - when the water does get in, it does stay there and apart from drain hole, no way of escape. Although I intend on going too far, I can't rule out any water getting in so need to repair.

Charleston14 - thank you for the video. I am going to go down this route providing the materials and equipment are not too much.

Thanka again for everyone else's help.

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Re: Crack in kayak

Post by ChrisJK »

Once you are sure it is dry you could possibly just use a silicone sealant or grab adhesive to fill the gap.That is if it is not overly stressed while in use.

andynormancx
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Re: Crack in kayak

Post by andynormancx »

Looks to me that it is way more than just cracked, looks like there are significant bits of broken plastic missing.

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J B Weld
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Re: Crack in kayak

Post by J B Weld »

Looks to my eye like the last owner has been a bit daft and plonked his behind down in the seeat way to hard/quickly with the kayak has been on the ground.

Interesting that he blames you, yet the damage is filthy dirty whoch indicates that it is probably years old.

Do you mind me asking how much you paid? If it were more than a couplemof hundred quid id ask him again to refund, or else serve county court papers on him for the small claims track.

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Re: Crack in kayak

Post by Sean_soup »

Plastic welding is a much more difficult thing to get a decent result with on your first attempt than a repair to a fibreglass kayak. Like other forms of welding the trick is to melt enough of the material to get a decent amount of penetration in the weld without melting *too* much and blowing a big hole in it. It isn't desperately difficult, but there's definitely a knack to it and you probably wouldn't want a repair like this to be your first go. If it's possible for the OP to get someone who knows what they're doing to fix it, that's probably the way forward. As a DIY job it would be best to get some practice on something else first, and it's probably going to mean spending more money on tools than the cost of paying someone else to do this one repair.

When I found myself needing to repair my plastic boat, I discovered that you can buy welding rods from Pyranha for about a fiver for half a dozen tiny rods. Casting about on ebay & FB 'marketplace' I found someone selling an old Burn with a massive split in the hull - something to practice on and a lifetime's supply of filler material for the price of a handful of packets of welding rods.

I'm no expert by any means, but having had a fairly extensive dabble imo no amount of broddling about with a soldering iron will get a decent result. It's a bit too hot and it's too localised a source of heat. Plastic is a poor thermal conductor and it takes time for the heat to penetrate so you don't want to be vaporising the surface while it's still stone cold a millimetre below. A decent repair will definitely require some filler material, which needs to be a very similar plastic, ideally identical. (Materially/chemically - the colour doesn't matter.)

Personally I'm sceptical of that business of pushing mesh into the plastic to reinforce the weld. Great idea if you can support the back while pushing on the front possibly, but otherwise I just don't think it's possible to apply enough heat and pressure to sink the mesh in without horribly deforming the whole thing. I would be more inclined to try 'stitching' the crack with hot staples sunk well into the plastic before welding over the top.

I can't tell whether Andy is right that there's plastic missing, or whether it is just a crack and that's just the goop left over from the attempt to glue a seat over the top. Obviously if there is plastic missing it won't be possible to repair without having some more to patch the hole. And I agree with J B Weld that it seems incredibly unlikely that the previous owner was unaware of this damage that was obviously done some time ago, probably before the seat was glued on over the top.

Thesmoothound
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Re: Crack in kayak

Post by Thesmoothound »

Hi. Thank Sean-soup for the great response. I am a bit nervous of doing this for first time but do have a similar type material I can practice on. With regards to the comment by Andy. There is no piece of plastic missing. It is just the angle of the photo.
The crack does look quite old so would imagine it has been done a while ago and the owner knew. The kayak cost was alot to me but in the grand scale of things, not enough to get into legal dealings. Hopefully I can fix this and have some fun on it when the weather improves. If I really like kayaking, then I can look at buying something better.
Thanks again for everyone's help. Seems a great group you have here.

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Re: Crack in kayak

Post by Chris Bolton »

I would weld the plastic as in the video, which would make it watertight. The welded plastic can be more brittle than the original, and you won't be able to see how thick the weld is, without access to the other side, so there's a risk that it will crack again. So I would then cover the seat area with fibreglass to spread the load onto the sound plastic. Use Chopped Strand Mat, otherwise known as CSM, and polyester resin. East Coast Fibreglass is good for buying mail order, but for this job, you could buy a kit in a car shop like Halfords (I don't know which would be cheaper). To help it bond to the plastic, roughen it as suggested by Ceegee, and then it would help to very quickly pass a flame over the plastic - not to melt it, just to oxidise the surface, less than a second in any position. Paint the resin on, stipple the mat into it, add another layer and stipple it all flat. Then when it's cured, glue a new foam seat over it, so that any sharp bits of fibreglass don't stab you.

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Re: Crack in kayak

Post by Ceegee »

Chris Bolton wrote:
Tue Jun 22, 2021 10:14 am
To help it bond to the plastic, roughen it as suggested by Ceegee, and then it would help to very quickly pass a flame over the plastic - not to melt it, just to oxidise the surface, less than a second in any position. Paint the resin on, stipple the mat into it, add another layer and stipple it all flat. Then when it's cured, glue a new foam seat over it, so that any sharp bits of fibreglass don't stab you.
I was specifically referring to a GRP patch onto existing GRP. I doubt very much you will get glass fibre and polyester resin to bond to PE, even mechanically, under any circumstances, even if you roughen it. It will just separate and trap water.

If you really want to go this way, I would make a fibreglass "bowl" using the method you suggest, then separate it and re-attach using a mastic sealant like Sikaflex. But that seems to be more or less what the original owner did, by gluing a seat onto the crack. JMHO.
Cheers,
Steve C. G.

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P4ddy
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Re: Crack in kayak

Post by P4ddy »

There is a liquid and powder mix that you put into a V made along the crack. I can't vouch for its strength and durability but it's a plastic weld without heat, just a liquid that I guess melts the new and existing together.

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Re: Crack in kayak

Post by Chris Bolton »

Steve, I agree a good bond is unlikely and was only thinking of it as a stiffening to spread the load. Making it not bond and then fixing down with sikaflex (cheaper but lesser sealants are available!) might be a good alternative. Or try to make it bond and it it comes off, seal it back on.

If not bonding to glass to the plastic, a further enhancement might be, having welded the crack, to tape over it with a Gorilla Tape to ensure watertightness.

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Re: Crack in kayak

Post by PlymouthDamo »

Thesmoothound wrote:
Tue Jun 22, 2021 9:58 am
Hi. Thank Sean-soup for the great response. I am a bit nervous of doing this for first time but do have a similar type material I can practice on. With regards to the comment by Andy. There is no piece of plastic missing. It is just the angle of the photo.
I had exactly the same boat as you with a crack in exactly the same spot. I got it fixed for free by a mate who had access to plastic welding kit in the car body repair place he worked in. You might be able to get it done very cheaply via that route. More details on this thread: viewtopic.php?f=4&t=127693&p=801563&hil ... ng#p801563 The fact that two boats have suffered exactly the same cracks tells you it's a weak spot so might be worth asking whoever does the repair whether they can fit any strengthening pieces (e.g. plastic tubes standing vertically or maybe blocks of polystyrene) between the seat and the keel before you weld it back up.

Thesmoothound
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Re: Crack in kayak

Post by Thesmoothound »

Thanks. Will see if anyone around here can do that for me. Thanks PlymouthDamo.

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Re: Crack in kayak

Post by Sean_soup »

Whereabouts are you? The odds aren't great but there's a chance someone might be able to recommend somebody.

Thesmoothound
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Re: Crack in kayak

Post by Thesmoothound »

Hi. Thanks Sean_soup but I have found someone who can help do the heat element. Thank you

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