When it's rot and when it's not

[geezer]

As new member of the wooden boat world, I seem to have opened a virtual Pandora's box of problems with my first purchase. I knew it wasn't going to be easy and I'm enjoying the challenge. I am reading voraciously and ask for plenty sound advice from this place. However one question continues to haunt me. How do I know rot from not? I think i have some and I'm all for getting rid of it, but when will a simple sand and varnish fix it, when does it require hacking out, treating and filling. take a look at this pic, the timber has gone very gray, and the grain has begun to spread and splinter. Should i chop out and start over?

maybe its impossible to tell from the pic.

http://farm3.static.flickr.com/2298/2206180647_b34acb75bd.jpg

Any and all advice is hugely appreciated.

[mike hanyi]

cant tell from the pic, what does your knife tip think of it? mahogany discolors any chance it can, does not mean it is shot, just discolored.

scrape off all the varnish fix the leak, odds are that window putty is the problem and needs the windows removed, the sills cleaned,and revarnished and rebedded, varnish it up and enjoy the boat, if you see lifting the next year it has moisture in there, I think you can get many more years out of it before it needs rebuilding.

I recieved a nice workboat that the keel is a bit soft, the owner said he knows it and I know it, but it may go another 5 years before it really needs replacement.

[geezer]

thanks mike. When I purchased the boat, the lifting in that area was horrific. Moisture had crept under my old canvas cabin cover. i sanded and varnished, and the varnish held. But i noticed a darkness creeping up the grain under the varnish, so i removed the varnish again. If i were able to pick bits out with the knife tip, is that fairly sure sign that its rotting?

[mike hanyi]

yes, I think if you could dry the area out well over the winter before varnishing it all up it will help, even pouring thinner in the area after the glass is out would help drive out the moisture.

a small computer fan set up will also dry it but beware of warping and cracks.

I dont think all is lost

[ssor]

The point of a knife is quite diffinitive. Probe some known sound wood to get a "feel" for solid wood and then you can confidently check suspect places. After that it is a judgement call.

[geezer]

yeah the judgment call bit is worrying me... but i have to learn.

[geezer]

which thinner do u recommend mike?

i hear this stuff is very highly spoken of.


http://www.lignu.nu/

[ssor]

Consider the location of the rot and the function of the piece. If the bottom inch of a chair leg goes bad it is a bother but if the rot is in the leg at the seat... well. Deciding what the consequence of a failure will be will help in making the call.

[pcford]

maybe its impossible to tell from the pic.
Any and all advice is hugely appreciated.

Looking at the picture is inconclusive. I would probably say no if this is the only clue. However, this is a common place for rot. (I do runabouts professionally.) I would tap the frame gently with a 10 oz. hammer. If the area does not have a clear ringing sound when you tap it...perhaps sounding like hitting a bowl or oatmeal, it's rotten.

(Parenthetical observation: Boats always look better in a photo. It brings a smile to me when someone puts an image up photographed of a boat sailing (say) 100 yards off and there is a cascade of cheers about what a beautiful job it is. Can't tell anything from a photo like that. Except that she floats with the bottom down.)

[geezer]

yeah, I have been taping away (with screw driver head) and it sounds kinda ok, when compared to sound wood. My main though concern is moisture, its there and i really wanna get it out of the wood. I have it in a few spots around the boat, can moisture be drawn out?

[pcford]

yeah, I have been taping away (with screw driver head) and it sounds kinda ok, when compared to sound wood. My main though concern is moisture, its there and i really wanna get it out of the wood. I have it in a few spots around the boat, can moisture be drawn out?

Again, I don't know if there is rot there or not. As I said, it is a common place for rot to start. However, it starts because the joint usually lets go...it may have get go but not started to rot.

To dry it out...putting heat on a boat make me nervous. Fire + boat=very bad thing.

If you are in a garage or similar space, just put a fan on it for a few days.

[Tom Hunter]

If there is rot it probably started low and worked up. So probe at the bottom. If you can dig into the boat there is likely some rot, if you can get your hand through into the cabin it is time to repair it.

Also, if you have a few spots and they are not bad you can repair them here and there over more than one season. Part of being happy is knowing what to repair and when.

[Flitch]

For what its worth, I am a AA Lumber Grader and have taught lumber grading classes for many years. The National Lumber Grades Authority says that rot breaks down easily under thumb nail pressure and may be easily picked out. This type of rot, also known as incipient decay, will continue to develop with the right conditions, unlike heart stain, white specks and honeycomb which develop only in living trees.

[geezer]

thanks for the info chaps