allene222

Fuzzy wood -- salt damage?

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After removing some battens that were covering some of my hull I found the underlying wood what is best described as fuzzy. It is just the surface as the wood itself is solid but there was enough fuzzy wood to clog the vacuum cleaner. I am sure some thickness has been removed from the hull as well.  The hull is strip plank mahogany and 63 years old. The areas involved have had the paint flake off. I don't know if the problem removes the paint or the lack of paint causes the problem.

The best theory I have been able to find is that it is caused by salt which gets on the wood and forms crystals when it drys and the crystals cut the surface of the wood. The competing theory is electrolysis but I can't see how that could happen over a broad area with no metal near other than the nails holding the wood in the planks. There are some nail tips showing and  no indication of increased fuzziness near them. The boat is not bonded, has an isolator type battery charger, and no AC. I will measure stray current again this weekend but last time there wasn't anything significant.

What I am looking for is someone who KNOWS what this is and hopefully can offer some guidance on how to address it. The only advice I have been able to get is that it is a slow process and you can't do much about it so just go sailing.

Allen

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It's the result of electrolysis that has eroded the lignum from the wood. Not that unusual with older mahogany. Nothing to be too alarmed about so long as the wood seems stable and has retained it's density beneath the fuzz. Probing with an awl will tell you what you need to know. Pulling a few fasteners in the area, too.

 

 

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That wood fuzz can really soak up epoxy and is often stronger that the original wood if coated well. Sounds crazy but I've seen it work.

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Here is the article that made me think it was salt.  I have heard the electrolysis theory but do not at all understand how that could cause what I am seeing.  Even if electricity were traveling through the wood, I don't see how it could hurt it.  I understand the electrolysis formation of hydroxyl ions which then dissolve the wood leaving just the cells or the wood. I have had that in the area of a zinc that was bolted to the hull and it did significant damage but looked nothing like what I am seeing. Tere is metal holding the wood together but the bits of nails and screws are not bonded to each other so I don't see how significant current could be generated. I guess anything is possible over a 60+ year period so it may just be my lack of understanding but can someone explain how electrolysis can make the wood fuzzy? I should have taken some photos...

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I had the same in some areas of the bilge in my plywood boat, luckily only where I was blocking it out for the new keel so it was all covered in epoxy. The solution is a penetrating epoxy timber preservative like Everdure. Strengthens the timber so you can then sand it and repainted it. 

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Have seen something similar also not sure of source, like dryrot, all lignum gone out of grain.  On a double planked hull a small leak could migrate a bit.  The spot in question could be the outlet of a previous leak originating elsewhere keel bolt thruhull etc. There may have been some current carried in the SW.  Is there anything nearby that could have caused it old battery box location etc.

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Slight thread drift...……  "lignum" is a Latin word basically translated as "wood."  "Lignin" is the complex molecule in most plant materials that is distinct from cellulose and hemicellulose.  Lignin was first identified in the mid 1800's and was named from the Latin root.  Lignin forms the structural integrity of most land-based plants and also serves as the cellular transport mechanism for nutrients.

In the paper industry.  Papermakers (pulp mills) spend a lot of money and time getting lignin out of the wood to make paper.  

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Moonduster is likely right, Allen...

I have worked at a yard for 20+ years that specializes in wooden boat repair and restoration, and have seem my fair share of dilignification (or, more specifically, alkali delignification) which I'm almost certain you are looking at.

I've attached a brief PDF that goes over some of the common degradation issues with wood, and the one we (I think) are looking at with yours is covered in the final section titled 'Cathodically Protected Metal In Wood'... I have USUALLY seen this happen in an over-zinc situation, and it will be quite close to the CATHODE in the equation (as opposed to anode)... and I don't even need a photo- I can picture the 'fuzzy wood' exactly how you described it...

woodissues.pdf

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The only zinc I have is on the prop shaft.  That obviously connects to the engine but nothing else on the boat is electrically connected to it. Nobody would consider the boat over zinced with just the shaft zincs. The only metal being cathodically protected is the prop. I have seen wood destroyed by the mechanism described in the article and this wood looks different. What I am seeing looks nothing like the photo in the article for example. I have parts of my boat that look like that which were at one time electrically connected to ground but those wires have long since been cut.

I am off to the boat right now with my multimeter in tow and will see what I can find.

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I am back from my inspection. What I found is that there is a voltage between the wood and the engine of about .6 to .7 volts. If I connect them I get tens of microamps of current. The wood is wet and after thinking about it I would expect exactly what I am seeing.  The wet wood is in contact with the bronze that hold the boat together.  The engine is connected to the zincs on the shaft.  Zinc is about 1 volt and bronze about .3 or .4 volts volts so close enough. But all that says is that there is essentially a battery being made out of my boat.  Maybe that is the problem, maybe not.  The issue is what is the shelf life of that battery. If it has a short shelf life, that could cause ions to form that would eat the wood. Normally a bronze battery like on a boat has a 100 year shelf life unless you short out the batter with a bonding wire, which I don't have.

OK, for some pictures. Here is a keel bolt that 30 years ago had a bonding wire to it. Look for the upper keel bolt with the tapped hole in the center and the burned wood around it. The other bolts have other issues but you can ignore that. You can easily see the electrolysis damage to the wood.

image.png.f00419737bb8f34eb401a644cccad665.png

 

But that doesn't look like my fuzzy wood.  It is hard to see the fuzzy because I vacuumed the fuzz up. But here is the best photo I got today. Like I said, the paint is gone and I am unsure if the missing paint is a cause or a symptom.

image.png.16f099d8d5caa4698ee787754ff2eda0.png

 

So, electrolysis or salt damage?  I really am not sure. I would bet on salt damage but it seems to me the common solution is to dry the wood. The sait is either the direct casue or is the electrical path that in some unknown way is doing the damage due to the natural potential differences found in any boat. I can't avoid the bonding that is sited in the linked article because there isn't any. 

I followed what I read about getting rid of the salt in the wood as it isn't going to dry if it is impregnated with salt. I wet it down to give the sale time to dissolve and then really wet it. It is a pain to do because the paint flakes get in the bilge and clog up all the passages which then require cleaning out with a vacuum. Now I can wait and see if it actually dries.

Then I think I will follow the advice here and saturate with penetrating epoxy after it dries on my next haul out next spring. In the meantime, I will finish the racing season. If I can place 2nd in one of the next two races I am assured of winning the third season. That would be nice after missing the second season because I cut my finger almost in half but that is another story.

 

Allen

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Great article Suider, saved that one.

 

Pics kinda look like old boat with a painted interior. Maybe a leak at some point, the complete lack of discoloration makes the chem thing seem iffy.  

On your fix you might look at West info rather than going penetrating epoxy.  I've used a ton of it as a sealer and it works great but the whole restore thing not sure I'm buying. Probably better to use a router and mill down to clean wood and glue in a like wood.

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Yeah, I am not buying the electrolysis theory at all now. The wood is drying now that I washed it down which means there was salt pretty impregnated in the wood. I also found a wood plug in a storage compartment that gets wet and that plug looks the same but the bilge area around it looks find. I think the problem was the wet salty wood probably compounded by the batten that went across the frames to form a subfloor.  The battens were wet and the hull wood was also wet.

Upon further inspection, there really isn't that much wood gone considering all the fuzz that it created. I will measure it next week but I would doubt that there was 0.010 missing so probably something I got all upset about for nothing. At that rate it would take 5,000 years to go through the entire thickness of the hull.

Allen

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The advice from West Systems on one of their wood boat restoration videos is to not paint the inside of the boat but to just leave to old paint there. They don't want to epoxy it because you can't get a complete coat because of the existing structure, frames and such. The thing they emphasized was the same thing my shipright said which was to make sure there is good ventilation. Since poor ventilation was obviously the cause of the problem, seems like good advice. I have removed the sub floor and drilled some vent holes.

There is nothing I can do to reduce electrolysis as I have long ago eliminated all sources of potential electrolysis to the degree that I understand the mechanisms. I did quite a bit of research on the subject in writing my article on bonding. You might find it interesting.  https://L-36.com/bonding2.php

Allen

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We have a original solid mahogany stick circa 1962. It seems like there are a ton of variation of species called mahogany but one of the similarities is they can let go via rot dryrot etc and undetectable under paint.  I put a traditional cealing in our boat. Open at bilge and deck frames.  Pretty good thermal air flow. I would run around with a mallet on the inside at your next haulout.  It almost always looks worse than it is.

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I poked at the wood with a knife and found it solid. I plan to measure the thickness reduction tomorrow before my race.

I am very familiar with rot. One year I reached under to inspect the block that the rudder post went through. The through hull was bolted to that block. I poked it with a pencil which went right into it with no resistance. It was probably electrolysis induced rot. The steel gas tank and the bronze rudder through hull were touching.  I had asked Svendsens to replace it years before and they decided to just treat it with epoxy for some reason. We fixed it better than new. Another year I saw a little spot in the paint in the cockpit and put my finger through the plywood when I touched it. Old boats are full of surprises but I have calmed down on this area and think it is OK. I will have my shipright inspect it in the spring just to be sure. By the way, "true" or "genuine" mahogany is considered extremely rot resistance. My mast was spruce before I was dismasted. Now it is aluminum, a vast improvement in many ways.

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I DO have to admit, I was expecting something much more like the first picture when you said 'fuzzy wood'.... 

At least it was a good chance for some of us wooden boat weirdos to speculate!!

We have had at least SOME luck with Captain Tolley's on sections like that in the past as a way to seal/stem progression where a complete removal/replacement/etc wasn't in the budget/didn't fit into time constraints... anyway, good luck on the next 2 races!

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It's usually not the wood mahagany or otherwise it's the sapwood.  That little bit is so small etc. That's what I ran into, heart wood was fine but a vein of sapwood run out turned to poo.

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On 8/20/2019 at 4:14 AM, suider said:

I DO have to admit, I was expecting something much more like the first picture when you said 'fuzzy wood'.... 

At least it was a good chance for some of us wooden boat weirdos to speculate!!

We have had at least SOME luck with Captain Tolley's on sections like that in the past as a way to seal/stem progression where a complete removal/replacement/etc wasn't in the budget/didn't fit into time constraints... anyway, good luck on the next 2 races!

I must say I struggled to find the right word to describe it and came across "fuzzy" in the salt damage article I linked in post #4. I guess what freaked me out was that there was so much fuzz it clogged my vacuum but now that I have calmed down it really isn't that much.  I measured about .030 of thickness gone in the worst spot which while not insignificant is only 0.0005 per year so it is likely something else will kill the boat before a significant amount of hull thickness is gone. Somebody will point out that most of that likely happened in the later years but now that I have increased ventilation it should slow down so who knows what the rate is except it is a slow process.

We won the race Tuesday. 4 points after 4 races in a best 4 out ot 5 series. What I still don't understand is how we finished within 30 seconds of the three 41 foot boats with all the boats our size back at least 3 minutes and every boat in the race owes us time. And the course was basically two reaches where WLW should dominate. The previous week we were first to finish uncorrected but that was a fluke as all the other boats stopped just before the finish line and we sailed right by them. It is good to be racing again after 6 weeks off after my finger encountered my table saw.

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