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Git Rot

Posted by Hansen 
Git Rot
October 03, 2020 03:50PM
I have a MacKenzie double ender that was built in the 80's. Before I bought it, someone had reinforced the floor and outer chine with a pretty heavy layer of fiberglass and epoxy with carbon, then painted the inside of the floor. It has always taken on a little water but I could never tell where it was coming in. I figured with the way the glass isn't really sealed to the boat (see pic) the water was probably coming in all along the chine.
As such I've meant to extend the glass higher on the outside of the boat but haven't gotten around to it yet. So I've just taken care to let it dry as much as possible and hoped for the best.
Well my luck ran out.
I hit a rock pretty hard on the Green river over labor day so I did a more detailed inspection than usual, and I found a section of the inner chine and floor that are rotted out. Luckily the rock hit didn't damage anything and now I'm hopeful that this has been the source of the leak all along.
The rotted area is pretty small and the boat has spent at least the last 10 years (5 in my possession) in a garage in Utah where the air is dry so I think the damage is localized. In the pic with my fingers in it, my index finger is on solid wood while I'm pretty sure I could poke my middle finger all of the way through if I wanted to. The chine log is all but gone for about 1.5 - 2" but then looks healthy. Actually what I said about poking my finger through is not true. The plywood is squishy but the glass on the outside of the floor is stout. From the outside you can't tell there is anything wrong. Water still gets in since the black floor glass is essentially forming a big bathtub that is not sealed to the wood. No mystery about how the wood ended up in that condition right?
I would love to find a way to avoid full floor replacement or anything that involves reglassing the exterior. So, I'm hoping that since the rotten area is small that I can use Git Rot or another penetrating epoxy to harden the floor and then fill / patch the chine with reinforced epoxy with glass over the top for added strength.
Has anybody used Git Rot or similar products successfully?
Does this plan sound feasible to those of you who actually know what you are doing (this is not a category I would put myself into).
If I make this repair and then tape the outer chine to keep water out in the future, will that eliminate the problem or do I need to do something more? I've thought about glassing the inside but that seems like it will just make it that much harder for the wood to dry.
Thanks in advance to all for your advice and help.
Kindly,
Elliott



Re: Git Rot
October 03, 2020 07:13PM
I've never used Git Rot. Perhaps others with more specific experience will answer too.

Lots of people put glass on the outside of framed boats. Others argue this is maybe not such a good idea if the boat is also painted on the inside, because the bottom will soak up moisture from the inside, through cracks in the paint, and never have a good opportunity to dry out.

For a framed boat with glass on the outside I think it's best to use oil only on the inside, so there is a better opportunity to dry out.

Your boat will be fine. Sharpen an old screw driver and use it to gouge out any soft spots. Then wet those areas with hot resin (so it soaks in). Then fill with epoxy putty and call it fixed.

Why it does leak in the first place? Water coming in from the outside is different than water collecting inside from boots etc. That's a leak. To fix that you probably would have to glass over chine, perhaps with 6" inch tape, so at least 5" inches of glass goes up the side, above the chine.
Re: Git Rot
October 04, 2020 01:16AM
The glass on the bottom and chine traps water....which may mean any patch is going to fail eventually.

That said, a patch may last a reasonably long period of time.

I know nothing of git rot, but have used a System 3 rot fix kit to repair a garage door. The rot fix kit includes a borate solution to kill fungus in the dry rot, a very watery epoxy to saturate the treated area, and an epoxy putty (you can work it with your gloved hand) to fill any voids in the rot area. The bottom frame on my garage door was rotten where water had penetrated underneath the weather seal, especially at the nail holes that held the weather seal. The local overhead door folks wanted $2000.00 to replace the the damaged panel. I repaired it with $84 worth of rot fix kit. The patch has worked for six or seven years now.

Worth trying to repair your boat bottom, recognizing it may need more attention in the future.
Re: Git Rot
October 04, 2020 02:30AM
Replacing a bottom is a lot of work. I've done it.
Re: Git Rot
February 27, 2021 10:39PM
Ok, 4 months later I'm finally getting around to taking Sandy's advice and I removed the rotten wood today. There was more of it than I'd hoped. About 4"x9" overall. Can this still be repaired with poured / sculpted epoxy or does it need more structure than that?
If epoxy, should I put glass in the hole first? What about thickening with chopped strand or something that would add strength? Is that worthwhile or am I overthinking this?
Thanks for any advice.
Elliott



Re: Git Rot
February 27, 2021 10:57PM
Oh yeah, and say I needed to replace all of that black paint... is there a preferred brand or spec for a clear interior finish? Anything black that would be acceptable and not trap moisture so I don't have to do a good of a job sanding?
I also have to refinish some seat parts. Should that just be straight varnish? Again, preferred brands or mixes?

Thanks
Elliott
Re: Git Rot
February 28, 2021 02:19PM
For boards or fpr plywood that is not covered with fiberglass I have soured on ALL hard paint-like finishes. I prefer oil, which can be mopped on as a recoat at any time. I learned about oil from A.J. DeRosa of AJ's wood boat tours in Jackson (Wyoming). Actually he's Wilson Wy, a few miles West. Right on the Snake River. Can oil be colored? Blackened? I dunno. The wood can be stained first, with either an oil-based or alcohol-based stain. And then covered again, with a clear oil finish.

I just mix linsead oil and naptha or paint thinner. Some add a little Japan Dryer and other goodies. There are recipes on the web. Googling "wood boat oil finish recipe" yielded:

"Equal parts of turpentine, boiled linseed oil, pine tar. Add some Japan dryer. Greg Rossel in "building Small Boats" has this recipe: 1 quart boiled linseed oil, 1 quart turpentine, 1/2 pint pine tar, 1/2 pint Japan drier."

....there are dozens of such recipes
Re: Git Rot
February 28, 2021 05:25PM
Thanks Sandy
Do you think that hole can be filled with resin or do I need to add something more structural?
Cheers,
Elliott
Re: Git Rot
February 28, 2021 05:30PM
It's an old boat. Almost anything you do will improve it. By "that hole" if you mean the plywood area near the chine, where gouging out rotten plywood left a big round divit, yes I might use a first coat of warm thin resin, followed by a soupy mixture of resin and fibers of some kind. More or less any mixture of powdered silica and/or linen fibers and/or micro balloons.
Re: Git Rot
March 06, 2021 03:42PM
The area that needs to be patched does not need a resin fill. That would be a waste of expensive epoxy. Saturate the patch area with penetrating epoxy, then fill with epoxy putty of some sort. One option is System Three rot fix kit. It comes with a borate solution to kill fungus, then penetrating epoxy to seal and harden the patch area, and finally a putty that can be worked into the patch area and sanded fair.

I suspect that many of the major epoxy suppliers make similar products. Usually used in repairing architectural stuff on old buildings, where the cost of replacing a specialty item is way more expensive than a repair using epoxy putty.
Re: Git Rot
March 06, 2021 04:55PM
....buy that putty pre-made (System III fairing putty for instance) or make your own with resin and fibers and microballoons. Or what ever.
Re: Git Rot
March 06, 2021 05:44PM
There isn't much wood left for penetrating epoxy to grab. Should I taper the surrounding wood like a scarf joint so the patch has something to bond with?
What about adherence to the remaining layer of glass floor... that is all that is left after removing the rotted wood. Is scarifying it adequate to get a good bond or do I need to chemically solvate it? If it needs to be "softened" with chemicals, will acetone work or do I need MEK?

Thanks!
Elliott
Re: Git Rot
March 06, 2021 09:55PM
I think I see the photo where a hole exposes an outer layer of glass--looking at it from the inside. Don't taper it. Don't use chemicals. Leave it just as it is. The rough edges of the hole will make a good bond. But do blow it out with an air compressor or better yet a hand held can of compressed air.

Soak it well with warm resin. Heat the resin and hardener separately, before hand, even to 90 to 100 degrees Fahrenheit. When they squirt resin into bottles at the factory they often heat it more than that, in order to make it almost like water.

Then mix that warm resin well. Slobber into the big divit with a brush. Immediately (no rush but don't wait) fill the hole with putty, or with putty and a chunk of wood. You can buy the putty or just mix your own. The putty should not be heated like the first penetrating coat. Warm putty will harden too quickly, likely forming a chain reaction that cures to rock solid in 30 seconds or less.

I often (always) heat pure resin, for soak coats like this or for laminating glass fabric. But I never heat resin for making putty.
Re: Git Rot
March 06, 2021 10:49PM
Thanks Sandy
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