Repair to bulkhead joint?

Hello to all.
I went on the water most of today and I just got home. I found today the bulkhead behind the seat on my Necky Chatham 17 (plastic) is leaking at the 6:00 position. If I push on it the bottom will move back and forth about 3/16 of an inch.
I am thinking I could use a syringe and a needle with a larger bore to squirt glue into the place that it’s become loose, until it oozes out both side so I would know I got it all filled up.

But I don’t know what kind of glue to use. The bulkhead is foam, and about 2" thick as near as I can tell. Have any of you done such repairs and if so , what is recommended?

I thought about Barge Cement because it will grab foam, but I am unsure and if something else is better I’d love to know about it.

Lexell seems to be the sealant of choice.

Do clean and prepare the boat surface well, as not much likes to adhere to it, so give it as best a chance as possible.


I read a lot of web pages. Possibly even on this forum. There are two products that I saw recommended constantly. One was a 3M adhesive called 5200 ($19 a tube and the complaint was getting it out of the grease-gun style of metal tube). The other highy rated product was Lexel, a clear adhesive in a clear tube, like typical caulk gun plastic tube ($9 at Lowes). The main complaint was can’t read the fine print on the clear tube. I bought a tube to seal a 3" neoprene foam bulkhead I made to replace a trashed one in a used Tsunami. (It looked like a hungry badger got trapped In the rear compartment and tried to claw its way out. In point of fact, the hatch had been replaced). MI forced the new bulkhead in place but waiting for a cool day to crawl around and do the job.

Research seems to indicate that silicone caulk is the common bonding agent used; however, multiple sources and technical explanations indicate that silicone WILL NOT stick to the roto molded plastic (if that’s your material). If silicone was used, the sources recommend cleaning the area with something like acetone, then abraid the area with 60 grit to aid with a mechanical bond. Actually, I havent done it yet, because I dread the idea of crawling around in the tight space more than I hate cold, boiled mutton. Sorry no more to offer. Hope that at least give you a place to start your research and a possible source. One person said he was looking to see if they’ve made any advancements. One user who recommended Lexel said, “Why? It’s been working fine for ten years, why do you need something better?”

Thanks Jyak and PeterCA. I’ll see if I can pick some Lexell up tomorrow.

When I asked Boreal Design about resealing hatch rims, they suggested using Sikaflex. They also recommended cleaning the plastic very well and pre-heating it prior to application. I imagine this would also work for bulkheads.

3M 5200 marine adhesive sealant is one of the best sealants you can buy for marine use, but it does not adhere well to polyethylene .Aug 14, 2018

Current Designs uses silicone.

Don’t use Lexel on materials that exceed 200°F . Lexel doesn’t perform well with rubber or silicone materials. Aquaseal®, Kynar®, polypropylene, polystyrene foam insulation, polyethylene, Teflon®, vulcanized rubber, polystyrene insulation, and waxes.

[image] › products

Lexel® by Sashco

Lexel is what the kayak shop gave me for the same situation you are in (warranty claim). Haven’t used it yet. Interested to see how it works for you.

Third or fourth the Lexel. Used it on our plastic boats w same material bulkhead.

Consider it annual maintenance. On plastic boats over time of being strapped on cars etc this happens, usually shows up on the hull side of the bulkhead. It is no big deal. Should be using dry bags inside the hatch areas anyway.

Mirrors what I read. Crazy material.

Well I got the Lexel and forced some under the foam bulkheads, and then beaded it up around the bulkhead perimeters.

I will see how well I did tomorrow.

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I think it cures in a couple days. As in more than 24 hrs. Fine print on the tube. Somebody gave a 3 rating for that.

Many kayak manufacturers recommend Lexel. Sticks to almost anything that you will find in a kayak. Lexel develops a dirt and water resistive skin just minutes after application, tack-free in 30 minutes and cures firm in 2-4 days. Complete cure in 1-2 weeks. For a kayak bulkhead, the boat is probably usable the next day if not sooner. Much more flexible than many other caulks. Will cure underwater, although for best results with a bulkhead, try to dry and clean completely before applying. Dries crystal clear. Freeze stable in the tube and will not become unusable a few weeks after after opening like silicone caulks. I have a three year old tube and it still perfectly usable.

Due to the fact that bulkheads can be hard to reach, do not depend entirely on a caulk gun to apply or you’ll end up with a mess. Use disposable rubber gloves and put the Lexel on your finger to smooth all around the bulkhead. When you get all you can reach easily from the top, turn your boat upside down on sawhorses and get under it to finish the job.

Quickly clean up any Lexel that is not where you want it Once cured Lexel is extremely difficult to remove.


That’s right, I remember now that Lexel had side bennies. Good catch.

My thanks to you all.

I used the Lexel 2 days ago. I was on the water today for 8 hours with my wife and a friend, and all of us were practicing reentry drills.
Bulkhead didn’t leak at all.


Yaba daba do! I read that success hinges on cleaning silicone residue. Thank you for posting.

Prijon HTP plastic is supposedly known for not much sticking to it. Their website kit recommends a primer, two part adhesive (Weicon PE-PP 45) on inside bulkhead and then a clear sealant/adhesive (Mapeflex MS Crystal) on both sides of the bulkhead. Yipes.

Most likely I will try acetone clean up followed by Sikaflex 291.

Have used Marine Goop with good results on my Prijon boats. Other boats, I use Lexel.

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