electrolysis in wood

Discussion in 'Wooden Boat Building and Restoration' started by skaraborgcraft, Jan 2, 2024.

  1. gonzo
    Joined: Aug 2002
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    gonzo Senior Member

    How old is the boat to have iron fasteners. Are you sure they are not steel?
     
  2. Ike
    Joined: Apr 2006
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    Location: Washington State

    Ike Senior Member

    from my web page on corrosion
    Wood boats suffer from a special kind of corrosion called fastener corrosion or woodburning around metal fasteners. This type of corrosion is caused primarily by water seeps and oxygen starvation around the fastener, and over protecting the boat with anodes. Yes, you can put too many anodes on the boat. The fasteners in wood boats are generally metal screws but boat nails, rivets, and bolts also suffer from this. In many old boats the screws are galvanized. At the point where the screw meets the wood and oxygen is excluded, sodium hydroxide forms, which eats away at the metal and destroys the wood immediately around the fastener. Sometimes this can be spotted in bare wood by a dark ring around the fastener. But more often than not you cannot see any outward sign of this type of corrosion. Marine surveyors will often remove fasteners at random looking for it. Any fasteners that are corroded must be replaced. But, you cannot put a new fastener back in the same hole. The hole must be reamed out and plugged to get rid of the rot. Then a new hole must be drilled for the new fastener.
    Some good sources:
    USCG NVIC 7-95 Guidance On Inspection, Repair And Maintenance of Wooden Hulls https://www.dco.uscg.mil/Portals/9/DCO Documents/5p/5ps/NVIC/1995/n7-95.pdf

    David Pascoe: Surveying Wooden Hulls: Surveying Wood Hulls - Old Boats and Yachts: Marine Surveying by David Pascoe https://www.yachtsurvey.com/Wood.htm

    This has been a controversial subject for many years. But these two sources appear to be some of the best I have found.
     
  3. skaraborgcraft
    Joined: Dec 2020
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    Location: sweden

    skaraborgcraft Senior Member

    1964. I suspect they are galvanized steel, but without seeing them in person...? Its possible someone did have access to iron dumps even in the 60s. If I get the survey done, I shall drop by with a result.
     
  4. skaraborgcraft
    Joined: Dec 2020
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    Location: sweden

    skaraborgcraft Senior Member

    Thank you Ike!
     
  5. Dave G 9N
    Joined: Jan 2024
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    Location: Lindstrom MN

    Dave G 9N Senior Member

    I have a few links on nail sickness.

    Electrochemical Damage To Wood – the marine version of ‘leaky homes’ https://waitematawoodys.com/2015/05/15/electrochemical-damage-to-wood-the-marine-version-of-leaky-homes/
    Chris McMullen's website. Chris has a strong interest here.

    https://www.fpl.fs.usda.gov/documnts/fplrp/fplrp229.pdf
    Degradation of Wood by Products of Metal Corrosion

    https://www.fpl.fs.usda.gov/documnts/pdf1980/baker80a.pdf
    Corrosion of Metal in Wood Products
    Another one by Barker, more focused on metals.

    http://www.terryking.us/boatbuilding/Woodboats-Inspection, Repair, and Maintenance-USCG.pdf
    USCG Guidance on Inspection, Repair, and Maintenance of Wooden Hulls

    Did you ever build Surprise?
     
  6. skaraborgcraft
    Joined: Dec 2020
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    Location: sweden

    skaraborgcraft Senior Member

    Thanks for the links.

    No, I ended up drawing up a 26ft box keel hull, and built a half size wood model/test hull, that was used to test performance under power. It exceeded the speed length ratio and also the expected speed/hp compared to usual tables. My take away was that a box keel hull with a reasonable sized box with a flat bottom, does gain lift compared to a "normal" hull. I have the full size keel, stems, frames and transom all built. Not ready for a fully bonded set up due to lack of space, but i did get to batten off the full sized hull to check sizes, before dismantling.
     
  7. Dave G 9N
    Joined: Jan 2024
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    Location: Lindstrom MN

    Dave G 9N Senior Member

    That's too bad, I was looking forward to the build. Surprise is on my bucket list of low power, shallow draft, fast, efficient hulls that I will never get to build. Mostly Atkin designs now that I look at it. Atkin's Happy Clam is closer to the top of the list now due to the smaller size. I started with Schock's Coyote as widened by Weston Farmer and described in his book From my old boatshop. I think that you would be interested in Chapter 20, Power/Fuel. I had a ride on an electric powered widened Coyote built to Farmers offsetts. I found the fiberglass mold mentioned in the book outside Composites Engineering in Concord MA as I was leaving my dentist's office, so I knocked on the door and asked about it. Ted Van Dusen built one there with a carbon fiber honeycomb hull. The bare hull was 25 ft, 200 lb if I remember correctly. The mold disappeared when they moved or went out of business.

    Chris McMullen might be willing to talk to you about nail sickness. I don't see a way to PM his email address on this forum, but the link to his website may have it.
     
  8. skaraborgcraft
    Joined: Dec 2020
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    Location: sweden

    skaraborgcraft Senior Member

    That book s a good read! Depending on if I move from my current worksite, let alone country, I may also need to downsize. I was contemplating knocking up an Atkin "easy-goer" as an interim boat, boat it was just a bit too long for the trailer I had then.
    Was that electric Coyote owned by a guy called Denny?

    The owner of this boat has failed to respond to setting up a haul-out and inspection, so Im passing on it.
     
  9. Dave G 9N
    Joined: Jan 2024
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    Location: Lindstrom MN

    Dave G 9N Senior Member

    I'm bad with names. I had a ride with Greg on Lake Phalen, and Phil knows the owner. Haven't seen either since the pandem(ic/onium). The boat is on Lake Minnetonka, S.W. of Minneapolis. Someone at Urbanboatbuilders in St. Paul would know the owner.
     
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  10. sdowney717
    Joined: Nov 2010
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    Location: Newport News VA

    sdowney717 Senior Member

    Electrolysis is a local problem around fasteners, but can extend a ways thru wet wood.
    It is especially bad if there is DC current leaking into the water, like from a failing bilge pump circuit.
    I had to repair 2 white oak hull floors where the lower half 3 to 4 inchs was softened bad enough a knife could poke thru the wood. I simply cut off the bad bottoms of those oak floors and glued in new wood. I then added 2 new pieces of oak 1" thick to both tope sides of each floor to further improve the strength. These oak floors are 2" wide and some are very deep and they extend across the width of the hull planking on the inside. So these are large long pieces of oak. The 2 that failed are in the lowest forward part of the hull where water naturally collects, all the other floors with spikes look great.

    The reason this happened is these floors were spiked with a 1/2" wide and 12" long or so iron drift into the keel. Since it only happened in the vicinity of an OEM bilge pump circuit, and I know over many years that bilge pump and bilge pump switch have failed multiple times, it must be the cause of the damage. I pulled out 5 iron spikes from 5 floors in the vicinity and that was not too easy. IT does not need these spikes, they were used as construction aids when the hull was made. Other deadrise wood boats, they just lay floors (joists) across keels and there is no metal attachment to keel made.

    Only other place where electrolysis damaged wood was the thru hull water intake fittings for the engines. These were bonded to each other all across the boat, I removed the bonding. And moved the thru hulls to a more accessible location as they had been in front of the engines in an impossible place to reach, crazy. The wood damage there was minor.
     
  11. skaraborgcraft
    Joined: Dec 2020
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    Location: sweden

    skaraborgcraft Senior Member

    I see your hull looks in good shape after you removed that coating!

    The boat in question, since i last saw photos, seems to have soft wood removed and then bogged with epoxy filler over the hood ends of 4 planks including caulking seams. It looks like a fast fix attempt than dealing with the actual problem, not having seen any photos of how the job was done.
    If the underlying frames and backbone are solid, some extra fastenings through the planks, it might have a future. It spent the last 40 years in a marina. Having removed iron keelbolts that "looked fine" but were found to be 95% wasted in the middle, I tend to work on worst case scenarios these days. The fact the new owner has not used it and passing it on suggests he may have found something requiring more time and money throwing at it.

    You done a good job, if not "routine" on your Egg.
     
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  12. sdowney717
    Joined: Nov 2010
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    Location: Newport News VA

    sdowney717 Senior Member

    Yes, here it is today, I wooded it, it had Sanitred Permaflex on hull since 2005, and everywhere Sanitred was, the hull wood is perfect.
    For the seams I used Loctite PL premium polyurethane construction adhesive. For filling worn spots, I used Loctite PL mixed with sawdust.

    All of it remained pristine, did not fall off or squeeze out of seams. The transom wood, I had Loctite Black roof and flashing and I scraped it off removing barnacles in the water, so it was barish wood for about 6 years fully wet, and the PL remained in the seams. it has very minor worm damage, which I am happy to see.

    couple recent pics
    I had to use a power planer to remove the Sanitred, it is so tough to deal with. I removed all of it as sometimes it simply loses adhesion to wood and then is on there like a glove.
    Going to use gallon buckets of 5200 instead, and some heavy nylon fabric on the bow for better abrasion protection

    This was fully exposed to the sea, you can see barnacle bases on wood. This wood is simply premium knot free arsenic treated Thompsonized at factory pine deck boards. I put this on more than 20 years ago, as in an entire new transom and beefed up with larger framing, and no plywood behind it..

    upload_2024-9-28_7-2-38.png

    bigger view
    bottom looks good all seams are pure Loctite PL, no other caulking, it held together great. This glue is like a very strong closed cell foam, it does expand during cure. It stays on the wood, what happens if planks move being sponge like it compresses and expands, being closed cell it does not leak. You can see the little air pockets in the glue

    upload_2024-9-28_7-5-43.png
     
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  13. sdowney717
    Joined: Nov 2010
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    Location: Newport News VA

    sdowney717 Senior Member

    View of wooded hull, all seams are Loctite PL, filled spots Loctite PL mixed with sawdust. Still like the day I put this on 20 years ago. All bung holes are PL
    upload_2024-9-28_7-10-46.png

    upload_2024-9-28_7-11-26.png

    filled areas fully adhering, intact over 20 years.

    upload_2024-9-28_7-12-30.png


    the filler does sand down, but it is harder to sand than wood, so I find using a RO sander is best, not a rotary grinder.
    upload_2024-9-28_7-13-40.png
     
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  14. Dave G 9N
    Joined: Jan 2024
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    Location: Lindstrom MN

    Dave G 9N Senior Member

    Sdowney, you may find this review in Practical Sailor of a variety of sealants interesting. They tested Sika and 3M 5200 along with a lot of other sealants.

    The Nylon cloth is reminiscent of cascover. When using ballistic Nylon for SOF canoes, it is best to wet it and stretch it over the frame while wet so that as it dries, it remains stretched. After applying the PU coating, the stretched Nylon doesn't swell and get baggy. Something to consider when applying Nylon. 2 questions on the Nylon. What type of cloth? If it is 84o or 1050 denier ballistic Nylon, where do you get uncoated material? I have searched high and low and Spirit line is the only source I can find. No problem there, but a second source is always good to know. Their 2-part PU does work very well.

    I think you explained once why you have stopped using Sanitred, but I can't remember your reasons.

    I am skeptical of the use of 3M 5200 underwater, which is to say that I have read enough to hesitate to use it, but lack sufficient information to make any definitive recommendation. Some builders in VA have complained of problems with 4200 and 5200 getting lumpy before the tubes were opened. They switched to Sika and never looked back. I suspect that the problem was that the 3M product was packaged in plastic tubes while the Sika was in metal tubes, and that they had been stored too long in hot moist conditions. Before faulting 3M, I would want to know what the date codes on the packaging and how old the stuff was when they used it. There are some threads on the WBF that mention that 5200 can harden and get brittle over time. The only actual time I ever found was 15 years. Bob Smalser back in 2008 also mentioned adhesion issues with 5200 after prolonged immersion. The general consensus there was that 5200 was best only used along with fasteners.

    I don't want to sound critical here. From what I have seen over the years, you have done very well with your boat and choices of material.
     

  15. sdowney717
    Joined: Nov 2010
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    Location: Newport News VA

    sdowney717 Senior Member

    I am not using the cartridge tubes.
    I already bought one 5 gallon bucket of 5200 for $1000
    Supposed to last at least one year unopened and comes in a metal bucket. I figure it will go on pretty quickly when I get going with it.

    Never seen 5200 get brittle, never even entered my mind that it might, not heard of it.

    Here is some nylon cloth I bought, 1000 denier. The idea is not saturation, simply put 5200 on wood, then press cloth into it, or let 5200 cure on wood then glue cloth on with 5200, guess will figure it out as I go. I can also smear on a layer of 5200 on top the cloth. I wil probably press the cloth into a first layer of 5200, I will do whatever seems to be a good idea at the time. A lot depends on how well I can spread 5200. The 5200 cures very slowly will remain sticky a long time.

    5200 sticks well to nylon plastic flat sheet with 175 psi shear strength, I figure it will stick to nylon cloth better which has a profile. Don't see why it won't stick to the cloth, but of course will find out.

    Amazon.com: Xtreme Sight Line - 1000 Denier Nylon Fabric - 60" Width by 5 Yard - Silver - Tear Resistance - Water Resistance - Abrasion Resistance - Urethane Coated

    Urethane sticks to polyurethanes

    The best glue for sticking to polyurethane is a polyurethane-based adhesive. This type of adhesive is specifically designed to bond polyurethane to other materials. It can be used with polyurethane foam, rubber, and other substances. It is also resistant to heat and moisture so it won’t break down over time.
    What kind of glue will stick to polyurethane? - Remodel or Move

    Urethane is a specific type of polymer molecule that is typically used as part of Polyurethane1. Products coated with Urethane are water, stain, soil resistant, and are almost 100% impervious relative to medium loss pressure1. Urethane coatings are used for metals and are a two-part coating solution best used for exterior equipments2. Urethane is also used in corrosion management as a first line of defense against corrosive agents2. A quality coat of urethane offers great protection against UV rays, rain, snow and other weather-based corrosive agents2. Polyurethane coatings help protect substrates from various types of defects such as corrosion, weathering, abrasion and other deteriorating processes3.
    upload_2024-10-6_11-50-3.png
     
    Last edited: Oct 6, 2024
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