Q: Protecting bolthole from water?

Need advice. I have a beautiful new kayak made of 4 mm okoume plywood and fiberglass. I want to drill through the wooden supports on either side of the seat to install a backband with bolts. What should I use to protect the raw wood in the drilled holes from water damage? Epoxy? (If so, would the 5-minute homeowner-type be OK?) Silicone caulk of some kind?

Please advise! Many thanks.

And happy new year, PNetters. Here’s to much happiness on the water!

G in NC

Used Two Things
I’ve used silicone in the past but now use G-Flex. With Silicone I can at least peel it out if need be but G/F is pretty much for ever. Is this on the inside or through the hull?


Epoxy a segment of plastic straw in
the hole. Provides a little bit of extra insurance that the inside of the hole is protected from water.

You can also plan ahead, and use woods like mahogany for places you will need to drill later.

If it was me,
I would put a coat of epoxy or two and then I would also use a rubber washer with a stainless washer over it , under the bolt head

Jack L

3M 4000/5000
available at Home Depot, sometimes, or WEST, thinly placed over Jack L’s recommendation of Gflex. this is top notch.

Spar varnish is acceptable with the 3M.

Hard telling what cracks until the surface does or not crack. Two or more thin coats of anything on a properly prepared surface with an eye toward mating the coating’s flexibility, coefficient of expansion/contraction to the surface…should waterproof: if you inspect the area during maintenance intervals.

you know what I mean, right ?

A SS washer with the rubber pad on the washer is also possible.

the washer and 3M allow cushioning, conformity to boat curvature, protecting the epoxy, sealing gapage.

Use SS nylocks for nuts.

WEST SS is a degree better than True Value’s

two washers
with rubbers each bolt.

Thanks, all, for your suggestions
Will probably use epoxy. I had not thought of a rubber washer in addition to a stainless steel one. Good idea.

Doug, this hole will be inside the boat. Goes through a vertical support, a strut you might say, from hull to underside of the deck on either side of the seat.

I am going to bolt in a Snapdragon seatback, the kind with the hard plastiic strap.

Thanks again, everyone, for the good advice.

Definitely use epoxy and two coats if possible.

You want to keep any water out of the wood.

The slower the cure time the stronger it will be.

Epoxy to seal the cut wood fibers, and rubber gasket/donut to allow a tighter seal when the bolt is secured.