Best Adhesive for Fiberglass???


I have been trying to glue a plastic pump holder to the inside of my fiberglass kayak and it keeps coming off.

The pump holder is smooth hard plastic (not the easiest to bond to glass). I have tried 5 minute epoxy, 7 minute epoxy and marine grade epoxy. None seem to work all that great.

I recently piced up some Marinetex…maybe that will work better.

what do you think would work best for this apllication?



I would think the marintex would work or boatlife caulking, how ever I feel the best because of the smoth plastic would be 3m 4200.

the 3m 4200 is not quite as strong as the 3m 5200 but the 4200 was made for smooth surfaces like plastics and gel coats.


Could you glass in something?

– Last Updated: Mar-13-07 8:56 PM EST –

Pick up some fiberglass cloth and west systems epoxy and hardener and glass in something. It'll stick. Maybe a nylon web or a sleeve or something to go around the pump holder. If you dont like what you end up with you could just hack it out of there and try something else. No harm done. I would bet it will be cheaper than buying 6 different types of glue.
Just a thought.

I have a pump holder made out of pvc pipe attached with epoxy. Epoxy won’t stick to smooth plastic so I sanded it with sandpaper until it was rough and drilled several small holes where it would touch the kayak. This gave the epoxy something to bond to. I’ve been using the pump holder for over a year with no problems.

Second the sanding suggestion
I think epoxy should work fine if you roughen up both surfaces a bit before attaching.

The way to do it is to find Nystroms
section of photos on it, and form a couple of pieces of two inch minicell into a clip, and glue them in with weldwood contact cement. Soft, lots of surface area, and done by at least 20 people so we know it works.

composites adhesive
Sand both surfaces with 80 grit. Clean both surfaces with acetone. Bond with Plexus from Jemestown Distributors.

We attach adjustable plastic footpegs to Kevlar w/ Plexus 420A - 12 minute pot life - never had one come off in three years

3M PT1100 ?
Not sure if it will bond to fiberglass but 3M PT1100 is a waterproof double face tape made to bond auto trim pieces. The stuff stick really well. I am in the process of building a trail camera and that is what is recommended to create a waterproof seal between the glass lens and the plastic Pelican dry box. It can be bought on Ebay for about $6.

Well, I have had a hard time roughening up the plastic, as it is very hard. Even a file is hard to get it roughed up…

However, now that I think of it my bond has primarily failed at the fiberglass and NOT at the plastic.

This next time I will try cleaning the surface more thoroughly with rubbing alchohol. Also will sand the glass a bit. I had not previously sanded the fiberglass because it seemed to have enough texture to it (I am gluing on this item to the inside of the boat).

I’ll try it again. May try that Plexus stuff next if this does not work, but not sure where to get it. Will look online.


Adhesive is sold at Wal Mart in the automotive section under the name Devcon Plastic Welder.

This is AWESOME stuff! Will adhere to plastic types that no other adhesive will work on.


Plexus info
Plexus can be had in small applicators from

The $50 380 ml tubes and $125 application gun are a little over the top for a single use, and the stuff doesn’t keep. We use a couple tubes a week and it gets hard to mix near the end.

Go to www.itwplexus to figure which variant will work best. They have a useful applications chart.

Here’s the link

I would use 3M’s 5200
When CSY Yachts were being built in Tampa 5200 was the only adhesive/sealant we used. The only drawback is once it sets it’s not easy to remove.

Gorilla glue
A friend of mine had a d-ring pull off his canoe, and it took the vinyl coating with it, leaving exposed ABS, which I would have thought was very slippery stuff. He sanded lightly and reglued with gorilla glue. A year later, the d-ring is hanging in, and this is where he attaches his thigh strap, so it gets plenty of dynamic stress. Cheap and easy, so maybe worth a try.

~~Chip Walsh, Gambrills, MD