Drying out the stringers...how much?
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Category: Repairs and Maintenance
Forum Name: Boat Maintenance
Forum Discription: Discuss maintenance of your Correct Craft
URL: http://www.CorrectCraftFan.com/forum/forum_posts.asp?TID=1930
Printed Date: May-20-2024 at 10:53am
Topic: Drying out the stringers...how much?
Posted By: tleed
Subject: Drying out the stringers...how much?
Date Posted: June-24-2005 at 3:51am
Can someone give me permission to complete my motor mount repair without completely drying out the stringers?
To review: when I drilled out some of my motor mount holes, some of the wood came out the consistency of moist, dark earth. I drilled out large holes at least an inch in diameter and cleaned out between the motor mount bolts. I bought enough epoxy to pour and seal and mount new stainless threaded rods in a sawdust/epoxy composite fill mixture.
I've had the dehumidifier on under a tarp now for about a couple of weeks. One pair of holes is still a bit damp. The others have felt dry now for several days.
The boat repair expert next door days I need to drill tiny holes along the stringers to check for dampness elsewhere in the stringers to allow it to dry along the stringers. He says I'll just lock in moisture if I seal up the motor mount holes now.
I'm impatient to get it in the water, since the tranny's been rebuilt, repainted, and is ready to go. I'm sure it's still wet inside the stringers, but if it will dry through holes drilled in the sides of the stringers today, it will dry next winter, and it was wet long before I started this project.
Is it a bad idea to drill these holes? If not, how large should they be? And why not go ahead and finish the motor mounts and wait until next fall to take up the whole floor and go after wet foam at the same time and go ahead and enjoy the boat for the summer, which is what I got it for anyway, not to add to my endless list of car projects…!!!!
Thomas
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Replies:
Posted By: mackwrench
Date Posted: June-24-2005 at 4:48pm
No permission granted. you should however drill or do whatever you can to let the water escape from the stringers and reglass the holes. If you shortcut this now, you'll be back later to finish it and it'll be bigger issue. Is boat in direct sunlight? keep a fan or somthing blowing on it 24/7 with the tarp off. The dehumidifier will take a while.....
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NO LONGER A MEMBER
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Posted By: Guests
Date Posted: June-24-2005 at 6:10pm
Wrong answer. Anybody else want to chime in here?
If I leave it outside it will get rained on and I'll be back where I started. Really, I see the value of doing it right the first time. I was just hoping for a different answer.
The dehumidifier is running 24/7 and it's doing the trick, just not as fast as I wish.
How big should I drill the holes, how far from the bottom, and how far apart, assuming I'm still hitting wet wood...?
Thomas
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Posted By: Guests
Date Posted: June-24-2005 at 10:31pm
Drill the holes and inject acetone into the timber, the acetone evaporates very fast and will draw the moisture with it,thats how I did mine 5 yrs ago. You will need to keep repeating the process a few times.
Dont rush the job, you will regret it
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Posted By: S.T.
Date Posted: June-26-2005 at 4:07am
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Do what 91 nautique said and be sure to use a specialty epoxy for the repair. A product like Git-Rot (www.boatlife.com) will wick into the voids in rotted wood and produce a stronger end result than regular epoxy.
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Posted By: tleed
Date Posted: June-28-2005 at 1:56am
Good news!
I took the above advice to heart and drilled a few exploratory holes. Didn't have to go far before I got to light brown, unrotted wood. And it was a bit drier than the wood close to the bolt holes.
So I don't think it will take much longer to dry it out. And I'm not going to fill it back in until it's nice and dry.
Thomas
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Posted By: David F
Date Posted: June-28-2005 at 12:26pm
ST:
I have no proof, just a hunce, that "Git Rot" and similiar products are nothing more than thinned epoxy. Thinning regular epoxy with Acetone will give the same results as "Git Rot"...especially if heat is added with a heat gun after pouring/injecting the thinned epoxy.
Thomas:
I am happy to hear that you decided to do it right and not cut any corners.
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Posted By: S.T.
Date Posted: June-28-2005 at 3:08pm
David F,
That's interesting that you can thin epoxy with acetone. Does it affect the final strength? Do you have to adjust the amount of hardener you use? I'm just wondering because it seems that it would have to react with something or else it would have to somehow evaporate out of the mixture.
The other thing about these products that are supposed to soak into rotted wood, besides the consistency, is that that their cure times are longer than usual. Anyway, the West Marine version of Git-Rot doesn't have acetone but it does have diacetone alcohol. I'm no chemist so all I know is that the molecule is a lot bigger than acetone. Here are the ingredients listed on the containers in case they mean anything to anyone:
Resin:
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Bisphenol A diglycidyl ether resin
Propylene carbonate
Diacetone alcohol
Alkyl glycidyl ether
Hardener:
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Triethylenetetramine
Dipropylene glycol monomethyl ether
Bis (dimethylaminomethyl) phenol
2,4,6-Tris (dimethylaminomethyl) phenol
Interestingly, the resin component doesn't really seem thinner than regular resin when you pour it out but after you mix it all together the result is definitely thinner than normal epoxy. The hardener might be thinner than the usual hardener.
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Posted By: David F
Date Posted: June-28-2005 at 3:22pm
Yes, the cure time is longer. You mix the epoxy normally, then add the acetone. I usually keep it under 20% by volume. I am sure the acetone eventually evaporates off during curing until you are left with only the epoxy resins. The point is that it works and the thinner mixture allows the resin to be soaked up by the wood fibers.
I am also not a chemist, but it seems to me alcohol in "Git Rot" is doing the same thing.
Incidentally, polyester resins can also be thinned, but Styrene should be used (no more than 20%) as Acetone will break down polyester resin.
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Posted By: jimbo
Date Posted: June-30-2005 at 5:08am
Ok, I have a degree in Chemistry but never heard of diacetone alchol so I searched the Net. It is a bigger molecule than acetone...so it will be slower to evaporate. The boiling point is 168 C (334 F). Water boils at 100C (212 F). So it really won't help evaporate the water. Acetone certainly will!
The best part is this molecule has twice as many "handles" to grab on to a water molecule. Acetoe has an oxygen atom hanging out there which the hydrogens on the water are attracted to (forgive the dangling participal). Diacetone has an oxygen as well as an "OH" (alcohol) hanging out there for a water molecule to grab on to (again with the dangling participal). This can do two things, one, allow the diacetone to get "sucked" deeper into the wet wood (being attracted to the water molecule) and two, the water will be attracted to the OH leaving the oxygen molecule free to bond with the polymer (like the acetone, or methyl ethyl ketone).
I'm not a polymer scientist, but that's my best guess without doing futher research. There is also the possibilty the diacetone would be metabolized by the wood rotting fungi to a toxic substance and kill the fungi (I'd have to check--or you could ask the manufacture).
Anyway, unless you kill the fungi, they will continue to "eat" the wood. Even if you seal off the hole with epoxy.
TLeed...If it were me, I'd take the additional step of killing the fungi that is rotting the wood. If you have the time, fill the holes with antifreeze and let it evaporate. The antifreeze will kill the fungi and anything else that's eating the wood. This will set you back in terms of drying out the wood (which I know you don't want). Check with the Git Rot manufacture. If their product doesn't kill the microorganisms, I'd do the antifreeze or a boric acid treatment. This link is a good read:
http://www.angelfire.com/nc3/davecarnell/rot.html
If you check with the Git Rot manufacture, post the results, I'm curisous.
Good luck
By the way, you could do the repair and get back in the water then address the rot issue (pour antifreeze in some holes drilled near the repair, then fill with epoxy) over the winter.
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Posted By: jimbo
Date Posted: June-30-2005 at 5:32am
Incase anyone cares, The antifreeze is metabolized to formaldhyde, which kills everything. Boric Acid disolves chiton (the stuff insect and fungi shells are made of (dp).
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Posted By: Jim_In_Houston
Date Posted: June-30-2005 at 11:53am
Jimbo,
I think you may have stunned the world. Are you referring to automobile antifreeze? To the best of your knowledge will antifreeze completly evaporate without leaving any harmful residue that will prevent epoxy from bonding to the wood?
By the way, I care and I would like any additional info on the subject you feel like sharing. Thanks!!!
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Happy owner of a '66 and a '68 Mustang
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Posted By: David F
Date Posted: June-30-2005 at 12:26pm
Jimbo:
Good stuff. If one of "Git Rot's" purposes is to kill rot causing fungi and acetone will not do this task (I would think acetone would kill anything), then I take back my recommendation to only use thinned epoxy and will recommend "git Rot" or equals. Who woulda thunk it?
Now, I always thought that if you dry the wood thouroughly, then fungi will die on its own due to lack of moisture...sort of like mold that needs moisture and organics to survive.
Incidentally, did you know that one of the main ingredients in Mr Clean "Magic Erasers" is formaldhyde?
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Posted By: tleed
Date Posted: July-01-2005 at 2:15am
All I want is to go vroom, vroom and splash in the water, and you guys are presenting advanced lectures in polymer chemistry! I'm so impressed!
Seriously, this is very interesting. I have been soaking my holes down in with acetone the past couple of days. Three are dried out nicely, and the third is the slow one. Dehumidifier is still going.
Antifreeze? That stuff will never dry out!
Boric acid. Now I could manage to try that. That's an ingredient you find in eye drops for pink eye, I think. White crystal that readily dissolves in water. Could dissolve it in the acetone.
Thomas
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Posted By: Jim_In_Houston
Date Posted: July-01-2005 at 2:41am
I like your attitude tleed. All I want to do is go vroom vroom too but pouring antifreeze in my stringers has thrown me a curve. I tend to take the advise of most the experts on this forum but now I am wondering...
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Happy owner of a '66 and a '68 Mustang
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Posted By: jimbo
Date Posted: July-01-2005 at 7:56pm
Oh ye of little faith...
Mold does need moisture to live. Drying everything out will kill the fungus, but spores will be left behind. When the moisture content gets right (and it will, or you wouldn't have had this problem in the first place), you've got a lot of spores ready to develop back into wood eating monsters.
Antifreeze won't really evaporate. It will be absorbed by the wood.
My best guess is the antifreeze will not significantly hamper bonding epoxy to the wood. Dumping boric acid or borax in the holes probable would. I'm slightly concerned about boric acid weakening the fiberglass.
Acetone will kill fungi, but it would take a lot more acetone alot longer to kill them than ethylene glychol. The antifreeze is toxic at a lower dose. Plus the acetone evaporates.
Here's some research on epoxy bonding to wood treated with antifreeze and boric acid.
http://www.maritime.org/conf/conf-reynolds-mat2.htm
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Posted By: Guests
Date Posted: July-01-2005 at 9:00pm
Had a friend with a 100 yr old farmhouse in Wisconson that had a big mold problem. After many experts advice he had to burn the place to the ground to solve the mold issue. So in perspective a little antifreeze seems reasonable.
Happy Fourth of July to all...i gotta go soak my hole in acetone...or have my wood absorbed or something like that
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