cockpit varnish

Jan 27, 2012
12
I think water intrusion under the varnish is something one deals with on a regular basis. This Fall right after hauling Muskrat in about a 2 week period all the wood under the varnish turned black on the inside and some what on the out side of the coamings. This all happened in the course of a few days. We had always had issues but this was crazy. We thought we'd have to bleach, stain, and maybe even paint (no!!!!) to remedy the looks, but when we used a heat gun the varnish obviously came off in sheets but the mahogany dried right out and came back to its correct red/brown color. Always thought once it turned black it was stained forever...

What do you all have for ventilation- we seem to have a lot of condensation in the sail lockers as well as leaks by the seat locker hinges. We have a single cowl vent over the lazarette. I hate to put any in the cockpit as that would allow water intrusion during one of those ugly moments we never want to have!
 

TomY

Alden Forum Moderator
Jun 22, 2004
2,758
Alden 38' Challenger yawl Rockport Harbor
Hi Jon. I too have some darkening where the cabin sides meet the deck(not much along the coamings). I just rebed the trim piece two seasons ago but did not renew the sealant between the glass and wood cabinsides beneath the trim. That was a mistake I think. I talked to a friend at Rockport Marine and he thought any darkening and or varnish lifting around this area was caused by moisture intrusion(period). Always the same, darkened wood means rot(takes water) on the surface under the varnish.

They(Rockport Marine) struggle with these joints on all wooden boats too(coamings to decks, cabins to decks). They actually epoxy some of those joints solid! I don't think that's a good idea for glass to wood but wood to wood, they know their business well(I've seen cabin to deck epoxy joints there, dry, hold varnish)

Anyway, I hope I can get the wood back to some decent state but I doubt I'll get most of the discoloration out(it's been going on for sometime)

But I plan to pull the trim pieces and really reeve out that joint both along the cabin to deck and coaming to deck area(tight space there). I used 4200 last time I think inside the joint, and that worked pretty well, for some time. Then I bedded the outer trim in Boatlife a couple seasons ago. There, I may have had a bad batch(Boatlife) which was too stiff to allow a good splooge out of sealant.

Lessen learned. Bedding wood perfectly is tricky. I may use another product this time. Thoughts?

That blasted joint can allow water in anywhere along the long perimeter, where the sealant isn't watertight, then let it can work along the length(easy once inside) until it finds a way inside,...and into a fastener (this is my hunch) that holds the cabin or coaming to the fiberglass deck.

Then the water works around the fastener and can lift and go under the varnish coating(no matter how good it is outside), and you're cooked! The water is inside now, under varnish at joints and fasteners. It may not leak a bit below(I did see a couple telltale single drips last summer after a real bash to weather) but it will cause rot(darkened wood)

I'm even thinking of cutting new trim all around, cabin and coamings, a tad oversized(to hide some damaged wood) and not setting and plugging the screws. Using oval head and leaving exposed. With the movement in this joint of wood to glass all around, I'm thinking it may be prone to needing rebedding more often.

What do you think?
 
Jan 27, 2012
12
Tom:

What surprised me was how the wood came back with just the heat gun- maybe we caught it in time and no rot- definately hard wood. However where we had some bad bungs on the toe rail that turned black a while ago we now have rot- black is a sign of rot to come?

How much ventilation do you have in the cockpit/lazarette area? When the engine runs we are warm, dry, and toasty but in the spring and fall with the large temp fluctuations we have tons of condensation. I think this might have been the cause of the quick change to black wet wood and the failing of the varnish.

The other thing we did last fall was to strip all the varnish and are letting the wood dry over the winter. In the past we just sanded the bad area to bare wood and recoated- maybe not letting it really dry out.

We'll see!
 

TomY

Alden Forum Moderator
Jun 22, 2004
2,758
Alden 38' Challenger yawl Rockport Harbor
Hi Jon. I have the same ventilation you do, one 3" cowl off the lazarrette. And the cockpit lockers leak like a sieve in a rain storm! I really don't see what I can do, the design, even with the detailed scuppers built below the openings, will never channel all water away from the lockers.

I don't put anything in the cockpit lockers that would suffer from the occasional drips. What I do is always leave two large doors open from the galley. I figure that allows most of the inflow of air through the 3, 4" cowl vents in the cabin through. A lot of air goes through the cockpits and exits out the not at all air tight locker top edges, and the small cowl. At any rate, that keeps things fairly dry back there, as long as it doesn't rain all summer....

You're doing the right thing drying the wood out first(I'm trying to keep things dry along the cabin/deck area under my cover for the same reason). The darkened wood is rot. If we catch it on the surface of the wood, it's not too big a deal. If we can stop the water, the rot stops. It can't continue without moisture, they tell me.

We've gotta stick together on taking care of these boats. They're worth it.