Kayak leak repair

I was recently gifted a sit on top tandem Splash II.  It seems like it would be fine for near shore, but I took it out to Del Valle to see if it is seaworthy first.  Turns out it has a slow leak somewhere and I had to stop and drain the water after an hour or two of paddling. 

I was going to hook up the shopvac tomorrow and spray some soapy water to see where the leak is presenting itself, but wanted to ask advice on whether this is effective and advisable.  I have seen kits that include the epoxy, even color-matched.  Has anyone had experience doing this repair for small leaks and if so, has it been successful?  Any advice?  It seems like it may be located near the scupper holes, but I have to investigate tomorrow to be sure.

Thanks for your expertise.

I had a small leak in my T13. I shored it up on some sawhorses and put water in to the waterline. There is like a seam in the scuppers where I think the mold comes together in production that was leaking. I used the KC welder pro and repair sticks. Its been bone dry so far. practice on a home depot bucket before hand. It gets hot and you can burn a hole right though you kayak.
Good luck

Great, thanks for the advice!  Going to do some test runs before I head out to the salt.

Welding plastic is tricky, but it can hold up well. In addition to practicing on a bucket, tear your test welds apart to see where the failure points are. If you can access the crack well enough, embedding some stainless steel mesh in the plastic when you do the weld is a good idea.

I tried using this before I saw the post on KC plastic welding:  https://www.loctiteproducts.com/en/products/build/epoxies/loctite_epoxy_marine.html

Would you recommend against using this as a fix?  I could go over it with the KC plastic welding tool, but this epoxy claims 3000psi.  Anyone have thoughts?

It's not the strength of the adhesive, it's getting it to stick to HDPE.  Not much will stick to that stuff, but if I were ever going to try an epoxy repair (and I wouldn't) I'd try West Systems G/Flex.

I think the KC welder pro is the best way to repair HDPE. Your actually melting the plastic back together. you can also get the welding rod in Hobie or Ocean Kayak colors. If that maters. watch all the vids on YouTube and practice first.
You can borrow mine for a while, if you want to try it out. I live in San Carlos and am working in Redwood city now.
Rob

Hey thanks for the info and the offer.  I was able to find one I can use and will give it a whirl before I head out again.  Hoping to be ready in time for crab!

Right on, maybe I'll see you out there. Were going out off Pillar Point for the  opener. Weather permitting

It's not the strength of the adhesive, it's getting it to stick to HDPE.  Not much will stick to that stuff, but if I were ever going to try an epoxy repair (and I wouldn't) I'd try West Systems G/Flex.

I’ e found that G/Flex sticks amazingly well to my kayaks. I haven’t done any leak repair with it, but I wouldn’t hesitate to use it if I needed something like that for a repair...

Instead of the soap and positive pressure check, try turning off all the lights, then dropping a bright light into the kayak. It will show all points of thinner plastic and will likely expose your leak.

I am sort of a recreational plastic welder.
There is not 1 tool that can seal any hole on any kayak. It is a craft and there are many tools.
I like to work with a live flame so a hobby torch is my favored heat bringer.
Bernzomatic is what I use but there are multiple others.