Kayak welding - Super Linear Polyethylene (SLP)

Gathering the stuff I think I'll need to install the new fish finder. First off, I'm going to need a good sized piece of blue SLP to do some modifications. I've contacted Cobra & heard back from a sales manager who wasn't much help. He said I could get a repair kit from a shop he suggested. The only repair kit I saw on the shop's website was for fabric inflatables.

I think I'm going to have to remove the existing rod holders to install tracks for a portable fishfinder & new rod holder. They have to be out of the way of paddling but still conveniently located, hence the need for enough SLP to weld over the holes. 

Does anyone have a good sized piece of blue SLP they'd be willing to part with? Hobie blue is a close enough color match, so some of that plastic would probably work well. Can some one help me out?

I've got a heat gun, then I'll get the welding kit described in this video. I'll post my progress on this project as it proceeds. Suggestions appreciated.

Thanks,
Paul

I think I'm going to have to remove the existing rod holders to install tracks for a portable fishfinder & new rod holder. They have to be out of the way of paddling but still conveniently located, hence the need for enough SLP to weld over the holes. 
Does anyone have a good sized piece of blue SLP they'd be willing to part with? Hobie blue is a close enough color match, so some of that plastic would probably work well. Can some one help me out?

Welding plastic is tricky.  And if you weld a piece of plastic on the outside of your kayak, it will create a bump on the hull.  Perhaps it would be easier to bolt a piece of plastic over the hole inside the hull with flathead screws, and glue the patch onto the inside of the hull with Goop to make the patch waterproof.  The plastic doesn't need to be the same as the hull of your kayak; it just needs to be flexible enough to conform to the inside of the hull when you bolt it down.  If you want the patch to be level with the rest of the hull, you could cut a circular piece of plastic the size of the hole in the hull and glue and bolt it in the hole in the hull and on top of the patch which is inside the hull.

You're right, it is tricky. I've welded some holes in my kayak before with a propane torch, putty knife & some leftover SLP no problem. Just takes patience & focus. It will be an easier job for me with the tools indicated. 

In my experience, the bolt down method doesn't seem to last & has a tenancy to leak. Do you have a specific glue in mind? The glues I've tried don't last or work that well for patching polyethylene, even with pre-sanding. Perhaps you've had better luck with that method. There is some poly glue I found called "Mr. Sticky". It might work, but I don't have any experience with it. http://mrstickys.com/poly-plastic-kayak-repair-kit-manual-mix/.

What I need is some SLP to fit the size of the hole, then weld it in place, sand it down a little, hit it with the heat gun for a few seconds & good to go. Doesn't have to look pretty, just needs to be flush so I can mount the tracks.

What I need is some SLP to fit the size of the hole, then weld it in place, sand it down a little, hit it with the heat gun for a few seconds & good to go. Doesn't have to look pretty, just needs to be flush so I can mount the tracks.

Sounds like you have a plan which will work.

I was suggesting that you use Goop between the patch and the hull to act as a gasket to keep the patch water-tight.  You are right that it's hard to find a glue which will adhere well to the various plastics which kayak hulls are made of.  A glue which does adhere well to kayak hulls is vinyl glue.  My repair kit for multi-day kayak trips includes pieces of raft repair fabric and vinyl glue, which can be used to seal cracks in kayaks.  I've used these materials to successfully repair kayaks on a number of occasions.  Here we are repairing a cracked kayak on a four-day kayak trip on the Jarbidge and Bruneau Rivers in south central Idaho.

Good info for an emergency fix. About how long will a patch like that last?

I don't know how long a raft repair fabric patch will last, because once a kayak develops a crack, you generally quit using it pretty soon.  But such patches hold up well because the raft repair fabric is strong and flexible and doesn't tear or crack when the patch gets slammed into or dragged over rocks.  I put patches on both the inside and the outside of the kayak in case something happens to the patch on the outside of the kayak, and I cover the patch on the outside of the kayak with duct tape to protect it from getting ripped off by jagged rocks.  It's a good idea to drill a small hole at each end of the crack to prevent the crack from continuing to lengthen.  Percussionists use this technique to keep cracks in cymbals from lengthening.

The guy whose kayak cracked on the Jarbidge-Bruneau trip continued to use the kayak for a couple of months in some fairly brutal creek runs until the manufacturer replaced the kayak under warranty.  Another example of how well these patches work is that early on a 9-day Class IV-V trip on the Rio Atengo in Mexico, the kayak I had borrowed developed holes under the seat from abrasion.  I patched the holes with raft repair fabric and used the kayak for the rest of the trip (it was that or hike out), and for a subsequent three day trip on the Rio San Nicolas.  Pictures from the Rio Atengo trip, the upper half of which was a first descent, and the lower half of which was a second descent, are posted at http://www.sierrarios.org/PagesGeneral/SlideshowLinks.html, Sierra Madre Occidental, Atengo 1, 2, and 3.  I took most of the pictures in those slide shows.

I have also attached raft D-rings inside kayaks with vinyl glue, and they have lasted for years with no problems.  When I tried to attach D-Rings with contact cement, the contact cement quickly pulled off the kayak.

Cool 
Know of anyone out there who has any old polyethylene kayak body parts I can use?

Sorry, I don't have any.  If a kayak cracks or wears through, we saw it up and throw it away.  Here is friend throwing away a kayak which developed an abrasion hole and crack this summer on our four-day Selway kayak fishing trip.

The blue plastic in the picture would have been perfect.

Anyone have the same plans for a similar piece of poly please pm me so I can help it go away.

I'm not sur if its the same plastic, but maybe find yourself a blue bucket of some sort. Use that for material.

PNW, this is your lucky day.  I e-mailed my friend and asked if he kept any of the plastic from his kayak.  I figured he would respond "Sorry."  But he replied "I have a ton of blue plastic.  I could drop a chunk off at your house if you like. I have a small piece hanging with my tools, big chunks in the attic."  So, what size and thickness of pieces of blue kayak plastic would you like?  Personal Message me with your address, and I'll ship it to you.

If you want to try to determine if my friend's plastic is compatible with the plastic in your kayak, my friend's kayak was a Pyranha.

I'm not sure if its the same plastic, but maybe find yourself a blue bucket of some sort. Use that for material.

It might be a little o/c, but I want to make sure I use some super linear polyethylene that's thick enough to make a solid patch. I'm fairly certain most kayaks are made of that material. If I use a plastic bucket, I'd need to know that it's also made of slp.

PNW, this is your lucky day.  I e-mailed my friend and asked if he kept any of the plastic from his kayak.  I figured he would respond "Sorry."  But he replied "I have a ton of blue plastic.  I could drop a chunk off at your house if you like. I have a small piece hanging with my tools, big chunks in the attic."  So, what size and thickness of pieces of blue kayak plastic would you like?  Personal Message me with your address, and I'll ship it to you.

If you want to try to determine if my friend's plastic is compatible with the plastic in your kayak, my friend's kayak was a Pyranha.

Thank you, that's going to be a big help. A couple 10 to 12 inch diameter rounds or squares should do the trick. Pyranha wasn't very forthcoming about what their yaks are made of, but I finally found a review that stated it's polyethylene. http://www.backcountry.com/pyranha-fusion-kayak

PM enroute. Thanks again.
- Paul

Two pieces of kayak plastic, six inches on the short side and more on the long side, are heading your way by U.S. mail, and should arrive on Monday.  The color matches your kayak pretty well.  Post pictures of how your welding job comes out.

Will do. Thanks again. PM me your address. I'd like to reimburse for shipping.