Gunwale finishing?

Hey guys, new user here. I just picked up a Mad River Explorer KX that had been sitting outside for a number of years, so the gunwales are shot. I removed the remains of them and am finishing up the new ash gunwales I cut to replace them. My question is this: Should I put a number of coats of “Gunwale Guard” on the inside (facing) surfaces of the gunwales before I attach them to the hull -or- should I put a coat or two of west system epoxy on the inside surfaces and treat the outside with the Gunwale Guard? Any suggestions would be appreciated…

Having West epoxy around, I would
cover those inner surfaces with a couple of coats. You know to clean the amine blush off the first coat before doing the second?

There wouldn’t be anything wrong with using Gunwale Guard on the inner surface, but I don’t think it would protect as long. It’s really a matter of whether you want to go to the extra trouble.

Penetrating Oil
I would recommend using some sort of penetrating oil instead of a surface treatment. Wood works best when it can breathe. Getting a good fit inwale to outwale and to the hull will minimize water intrusion. Hopefully you have inlet the inwale for the hull to give a stronger attachment of seats.

cracks from screws
I once was going to help a friend recondition gunwales that had sat outside a few years. We took odd the gunwales and they looked to be solid, but as we sanded them, we came to a spot where the wood had turned to powder on the inside, and the gunwale disintegrated. The culprit appeared to be a crack on the hull-facing side of the gunwale, that crack radiating from a screw hole. Apparently water had entered the wood via the crack, and over time had rotted away the inside of the gunwale.

Two lessons here: After ten or so years, the MR applied gunwale guard, or whatever they used, had adequately protected the inner side of the gunwale, and, no. 2, oil up those screw holes, too. You aren’t going to see any cracks caused by the screws. You are liable to have cracks whether you epoxy or oil the gunwales. So does that mean you need to screw the gunwale first, then remove the screw, then oil the hole? That’s inconvenient, but would seem to be the most reliable way of preventing water from getting in. If you are going to remove the gunwales peiodically for maintenance, you could treat holes & cracks at that time.

Good luck with whichever way you go. I just used oil when I redid the Chipewan’s gunwales. But, that 1974 hull is probably going to disintegrate before the gunwales rot, so I didn’t want to invest too much effort into perfecting the gunwale protection.


I think that is excellent advice

– Last Updated: Sep-25-08 10:51 AM EST –

I think the new gunnels will crack slightly after the screws are inserted. I'd oil the holes up good before finally assembling it. Then take the gunnels apart again in a year or so and oil again.

I use a syringe filled with Watco. With the gunnels removed, hold your finger tight under each hole, shoot oil in the top, remove your finger and the suction created pulls the oil down through the entire hole.

I've made removing and re-oiling the insides and holes of wooden gunnels a once every 2 or three year event. Like Boozetalkin, I've seen what happens without regular and dilligent maintenance. And, I've seen those small cracks eminating from each hole (on the inside) that you'd never know are there without taking things apart.

Cracks in wood?
I’m having a hard time wrapping my admittingly small mind around this.

Are the cracks from outside storage and the resultant freeze/thaw-swell/contract cycles? Or are they from improperly sized pilot holes?

Just curious.


I don’t know but both Vermont MR’s
… I have with wood gunnels have the same kind of slight crack eminating pretty much horizontally from each screw hole, visible only from the inside (for the most part).

My opinion is, the cracks may be caused
by twisting of the gunwales when the boat is banged on racks, or when the gunwales are pushed up or down when the boat is in use. This is the type of force most likely to start the cracks.

Such cracks should not occur just from the size of the screw, because, especially in the outboard gunwale, the “clear” hole should be just big enough to prevent such pressure.

Many ash gunwales I have seen are cut quite thin to hold down weight. But this narrows their base where they rest on the hull, making them more inclined to twist in a way that the base of the screws start cracks.

Winter expansion/contraction of composite hulls and ash gunwales should be insufficient to cause such cracks. If it is causing them, then one should see an asymmetry, with cracks being longer in one direction toward the bow and longer in the other direction toward the stern.

If my hypothesis is correct, then the solution is gunwales wider at the base, somewhat bigger “clear” passages in the wood toward the screw head, and even perhaps a bit of a clear pocket before the screws engage in the other gunwale.

I’ve only had two sets of wood gunwales to tend, one spruce and one ash, so I’m not claiming any expertise. But if cracks are often developing, I hope we can find a cause and a solution.

Even if the one inner surface is epoxied
there will be plenty of surface area on the narrow gunwales for them to breathe. And while epoxy is one of the most effective ways of protecting wood from water, it is never so effective as to prevent breathing. Penetrating oil may be a good-enough solution, but not better.

The ash outwales on my MR

– Last Updated: Sep-25-08 2:58 PM EST –

composite are 'kerfed'(or, more correctly, rabbeted) at a slight angle, so that the bottom edge contacts the outside of the hull and the top edge contacts the top edge of the inwale, leaving a slight, but present, triangular void. This, I think, is where there could be trapped water and water vapor that, over time and freeze/thaw cycles, might promote fungal growth and accelerate decomposition. The clamping effect of screwing the rails to each other would subject the inside of the outwale to tension perpendicular to the grain, possibly resulting in splits radiating from the screw holes.

I like the idea of regular preventive maintenance-pulling the gunnels for periodic inspection/treatment. Yeah, it's a pain, but not as bad as premature failure. I think this approach, rather than choice of finish, is important.

Very interesting.
Now I have something to look forward to for a late fall/early winter project.


Gunnel Retrofit
I suppose that one could, if desired, simply let the rails rot, then replace the ash with a more durable species like teak and forget about it. There would be a weight penalty but, if you don’t mind the dull, silver-grey look, they would likely outlast the hull with no maintenance whatsoever!

But, but, but
what would we talk about then? I thought half the beauty of wood brightwork was talking about refinishing???

Jim :wink:

But, but
the beauty of teak is that there doesn’t HAVE to be any maintenance and it’s been sustainably harvested for generations. The ugly side is the price.