dry rot? wet rot? not rot?

When I took over my boat from the PO last year, I was told that at some point in the past the cabin sole was under water, and had to be replaced. Indeed, the sole looked pretty new, and there were visible water marks on the bottom of the teak bulkheads all around the cabin.

All last season, I had water intruding up the broken rudder post and gland, which kept the bilge and the teak wet (anytime the boat heeled, I suppose). This spring, I finally got that fixed and the bilge is now mostly dry, except after heavy rains.

I suppose that wood has now had a chance to dry out, and some white powdery substance has started appearing where there used to be water marks.

Is that the fabled dry rot? What is the best way to restore the wood, or at least limit the spread/damage? I've done a lot of searching on the web, but can't really find anything that would work well in my case ... any ideas?

pix attached ... If you look closely, the wood in the 3rd photo (in the v-berth) doesn't seem to be affected by this rot, or has not dried out yet?

thanks in advance, Zoran

I think what you're seeing here is not necessarily rot. It's what happens when varnished wood gets wet with saltwater. The white stuff is salt, which I bet you can taste; it's probably been driven out by changes in humidity over time. The darker wood is the outer layer of mahogany plywood which has lost its varnish; it will act like a wick if more water gets in there, and now it's stained. It's possible but by no means certain that there's rot underneath this. Tap it with the handle of a screwdriver and see if you hear a dull thud compared to other similar areas that are not affected. The thud indicates rot or that the plies of the plywood have separated.

The big problem is that the bottom of the plywood wasn't sealed with epoxy when it was installed. (If you ever have to replace the bulkhead, do that--top and bottom!) That would have prevented, or at least slowed, moisture from wicking into the rest of the wood. We know this now--but from what I understand this was not standard boatbuilding practice.

You can try to get the waterstain out by sanding it lightly, bleaching, perhaps applying a new woodstain, and revarnishing. Odds are you'd have to do the whole bulkhead to get it a uniform color. This is a lot of work for something that isn't structural, although perhaps there are other ways to get it to match again. I'd probably sand lightly, not worry about the color, revarnish, and see what happens over the next few years.

I agree with everything Tenders has said; the one thing I will add is that where you have access to the end of the plywood, as it looks in one of the pictures should be possible, you may be able to feel whether the layers are separating. Small voids at the very tip are OK, but if you can feel the layers have come apart, and it extends into the plywood to any degree, you can expect the plywood to delaminate over time, the only cure to which will be replacing it.

Based on my flooding experience which had my sole under water for a few weeks, it takes prolonged exposure to do damage that is more than cosmetic; however you have no real way of knowing how long it was underwater, and the cabin sole having been replaced (looks good btw) is not a good sign.

For now I would clean it up and keep an eye on it for a while. It is not worth doing a lot of work to make it look better now if you will have to replace it in the future.

Gareth
Freyja E35 #241 1972

I have had some success repairing and stabilizing wood that is rotten and plywood that has delaminated. I like Smith Bros. CPES epoxy. Its a very thin epoxy, thin like water and it takes 7 or so days to cure. What it does is penetrate very rapidly and thoroughly into wood to stabilize it. It can require many applications. For restoring a paint grade surface it is ideal. RT

Indeed, I tasted the dust yesterday and it is salt. The layers are healthy, otherwise. I'm relieved and rather pleased, since this means my keep-the-bilge-dry efforts are actually paying off.

I'll probably just give it a light sanding, a good layer of MinWax wood hardener, then again a light sanding and a coat of satin varnish.

As always, thanks for the priceless guidance ...

Zoran