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Thread: Galvanic corrosion

  1. #1
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    Default Galvanic corrosion

    Just looking into fasteners for my stem and keel on the Ninigret build.
    Checking into galvanic corrosion - I am learning quite a bit about how this all happens and ways to control it.
    Interesting....
    some links:
    http://www.kastenmarine.com/metalparts.htm

    http://www.boatus.com/boattech/artic...-corrosion.asp

    I am sure many of you are well aware - but for those like myself I find the info important.

  2. #2
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    Default Re: Galvanic corrosion

    Thanks. Interesting chart.


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    Default Re: Galvanic corrosion

    Its a cool illustration, even looks like it is under water.

    Not much between 304 and 316.
    Is it the voltage that makes the difference between them?
    "People should be able to access these benefits [Social Welfare] as a matter of right, with no more loss of their own standards of self-respect than would be involved in collecting from an insurance company the proceeds of an endowment policy on which they have been paying premiums for years."
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  4. #4
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    Default Re: Galvanic corrosion

    Yes. The bigger the voltage differential, the worse idea it is to have them in electrical contact. The lower voltage one gets eaten.

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    Default Re: Galvanic corrosion

    Yep,....... use bronze.

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    Default Re: Galvanic corrosion

    Kasten Marine has a better reference on their site http://www.kastenmarine.com/_pdf/mbqMetRef.pdf

    There is a good book by Nigel Warren called metal corrosion in boats that is written for boat owners, not the MIT Materials Engineering Department.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

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    Default Re: Galvanic corrosion

    Whatever you do use the same material thoughout the boat. Mixing will make it worse, especially where you can't bond to sacrificial zincs...which normally shows first in the bottom plank fastenings around shaft logs and rudders. Above water line electrolysis is typically minimal to non existent in comparison and a totally different animal.

  8. #8
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    Default Re: Galvanic corrosion

    Quote Originally Posted by BillP View Post
    Whatever you do use the same material thoughout the boat. Mixing will make it worse, especially where you can't bond to sacrificial zincs...which normally shows first in the bottom plank fastenings around shaft logs and rudders. Above water line electrolysis is typically minimal to non existent in comparison and a totally different animal.
    Too much zinc can make you sink. Bonding isn't always a good idea. Other than that, no argument.
    https://waitematawoodys.com/2015/05/...f-leaky-homes/
    https://www.fpl.fs.fed.us/documnts/fplrp/fplrp229.pdf
    https://www.fpl.fs.fed.us/documnts/pdf1980/baker80a.pdf

    This thread has a lot of good information. I'm not sure how much of it is correct, including what I said: http://forum.woodenboat.com/showthre...ron-Keel/page2

    Dissimilar metals in a wood hull that are not bonded, see page 14 http://www.mcclavemarine.com/text%20...oden.Boats.pdf

    More galvanic corrosion, but almost entirely for metal hulls:
    http://www.vonborks.org/galvanic.html
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  9. #9
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    Default Re: Galvanic corrosion

    Most old work boats were fastened with hot dipped galvy then bottom painted with copper. I've often wondered how they lasted as long as they did.

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    Default Re: Galvanic corrosion

    ^ Well, " back in the day " it would have been tin- or lead-based paint, yes? Copper became the status quo in the 1990's, as I recall.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

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    Default Re: Galvanic corrosion

    That would explain it, but I do remember bottom painting with copper as far back as "72.

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    Default Re: Galvanic corrosion

    Copper bottom paint has been around for a long, long time. TBT didn't come into use until the 1960's. It was highly effective, and replaced a lot of copper paints until it was discovered to be so toxic, and more-or-less banned about 40 years later. Copper didn't replace tin, we just went back to using it.

    Note that copper based paint is better than tin, WRT eating zinc. So maybe the cheap Cu paints were best for old fishboats.

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    Default Re: Galvanic corrosion

    Thanks for the clarification, robm.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  14. #14

    Default Re: Galvanic corrosion

    "The Chemistry of a Current".

    I am a wooden boat builder with 50 odd years experience in the trade. Boats have always been my interest.
    For twenty years, I was in business building Wood, Steel and Aluminium craft. My company also ran a hardstand and operated a slipway and later a Travelift.
    I am very aware of the use of cathodic protection to prevent galvanic corrosion. It works but these days I feel it is often over used. Rather like “A solution looking for a problem’’.
    This Forum is about wooden boats, the same are like Dinosaurs and their numbers shrinking every year. I have written on https://waitematawoodys.com/2015/05/...f-leaky-homes/ in an amateurish attempt to try and save the small fleet of Classic Yachts and launches in New Zealand. I have been encouraged by Jay Greer and others to post my views on this Forum.
    I won’t repeat what I have said in the past but can I suggest we approach electrochemical wood damage caused by the use of bonding and Anodes from a different angle to that of a metallurgist. Please remember I want to save the wood, the metal can be replaced.
    I believe “Electrolysis of Sea water” is the cause of the timber degradation.
    With Electrolysis of Sea water you get Chlorine and Oxygen gas around the Anode + and Hydrogen Gas around the protected negative – Cathode. It requires a small electric current.
    My research in books and from experiments, have led me to believe and witness 1.3 volts DC between the positive and negative electrodes certainly starts gassing in the sea water electrolyte. The result of this gassing is Sodium Hydroxide or Caustic Soda at the Cathode or protected metal. On wooden boats this chemical gets trapped under great pressure between the wet wood and metal. It is washed off the exposed metal but can be seen inside the hull as white powder forced out, around bonded underwater metals.
    I you check the Kasten Marine “Average Voltage in Sea water” chart you will see Manganese brass and Zinc listed with almost .5 volt difference in potential. Using a Silver Chloride cell as a reference my readings are in fact .65 volts.
    In my experiments I see no gas bubbles with these two metals coupled together (with no external voltage.) Add .4 of a volt DC current .02 amps to the Zinc anode and you certainly see the gassing around the cathode. My actual Hull Potential Meter reading 1.4 volts rather than the 1.04 I expected.
    I and many others have observed that wood boats with anodes typically have wood deterioration around bonded thru hulls and propeller and rudder shaft tubes. I ask, why should this be if there is no gassing round the cathode?
    To get the alkaline damage there must be Sodium Hydroxide and to make Na OH there has to be hydrogen gas and sea water and a small electric current.
    Rather, the Electrolysis gassing starts at a lower level than the 1.3 volts quoted in my ref books and / or the Hydrogen bubbles are so small I can’t see them. Another possibility that seems likely, there is a positive leak of over .4 volt DC in the wet wooden boat from the ships battery’s and that voltage is added via the bonding to the potential of the zinc anode. That may sound far fetched as wood is supposed to be an insulator.
    I my test today I introduced 12 volts to the zinc anode via a two foot long piece of 24% moisture content ( note sea water) heart Kauri. I observed the Manganese Bronze (brass) Cathode gassing. Most wet wooden boats I have tested have a high resistance positive leak in the hull. Often impossible to find, this phantom voltage added to the zinc anode potential may be the source that starts the gassing that causes the wood damage. Whatever, alkaline damage certainly happens but slowly.
    The point I am trying to make. If you do not have the zinc anode and bonding the small DC leak would not matter. It is the sum of the voltages that seems to cause the electrolysis.
    Interesting, the size of the zinc anode does not seem to matter, I get the same result using a block of zinc or a 4 inch Galvanised nail.
    To do these tests I purchased a variable Voltage and current device as used in a laboratory.
    I have a hull potential meter and a sensitive Avo meter. I use two buckets of sea water for my experiments.
    Please note, I don’t consider myself an expert. We all hear conflicting myths of black magic from people who are more interested in selling anodes than the longevity of your wooden boat. The truth, I believe has been written years ago but the same is hard to find.
    Anyone interested in sharing their knowledge can write to me via the forum or privately.
    I am doing these ongoing experiments for my own interest and curiosity not for any commercial gain. I guess, to prove conclusively what I have known for fifty odd years. “You don’t put Zinc anodes on a Wooden Boat”. I never knew the reason why, but I knew it was wrong.
    Chris McMullen
    Auckland. New Zealand
    Nov 2018
    Last edited by Chris mcm; 11-10-2018 at 04:40 PM. Reason: mistake

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    Default Re: Galvanic corrosion

    When I built my version of the Ninegret I did not use a single metal fastener other than what was necessary to hold cleats, chocks, etc. The hull was held together with epoxy. I know you want to avoid using epoxy, but just sayin.'P1010002.jpg

  16. #16
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    Default Re: Galvanic corrosion

    I replaced all the brass fasteners on my ‘57 Lapstrake. All showed loss of zinc. Under a microscope some looked like Swiss cheese.
    Kind Regards,
    Tycer

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    Default Re: Galvanic corrosion

    Quote Originally Posted by Chris mcm View Post
    "The Chemistry of a Current".
    To get the alkaline damage there must be Sodium Hydroxide and to make Na Cl there has to be hydrogen gas and sea water and a small electric current.
    Rather, the Electrolysis gassing starts at a lower level than the 1.3 volts quoted in my ref books
    Chris McMullen
    Auckland. New Zealand
    Nov 2018
    I can't argue with you on any other aspect, but you don't need to form hydrogen gas to drive pH. As long as you generate some imbalance in the ionic concentration, water will dissociate to balance things out. All corrosion currents locally affect pH, and voltage gradients can concentrate ions. The standard potential for electrolysis is 1.23V, 1.3V is close enough if you aren't under ideal lab conditions.

    Change of topic: Copper paint ban delayed.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  18. #18

    Default Re: Galvanic corrosion

    Thank you MN Dave for your interesting reply. Just the sort of help I hoped I would achieve by posting on this Forum. Hard doing these experiments on your own. More research required for me to start understanding this chemistry.

    Quote Originally Posted by MN Dave View Post
    I can't argue with you on any other aspect, but you don't need to form hydrogen gas to drive pH. As long as you generate some imbalance in the ionic concentration, water will dissociate to balance things out. All corrosion currents locally affect pH, and voltage gradients can concentrate ions. The standard potential for electrolysis is 1.23V, 1.3V is close enough if you aren't under ideal lab conditions.

    Change of topic: Copper paint ban delayed.

  19. #19
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    Default Re: Galvanic corrosion

    I don't know what it is but there's something missing and too many variables in the formula that says "no zincs" on wood boats for me to go that route. Empirical evidence highly favors zincs and bonding over boats without zincs for large wood boats kept in the water 24/7/365. There are probably 100s of 1000s of 25-50 yr old wood boats that haven't shown electrical damage to the wood and 99% of them used zincs and a lessor amount with correct bonding. What do the SAMS and NAMS surveyors say about not using zincs on wood boats? Not arguing or debating, just curious.

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    Default Re: Galvanic corrosion

    Quote Originally Posted by BillP View Post
    I don't know what it is but there's something missing and too many variables in the formula that says "no zincs" on wood boats for me to go that route. Empirical evidence highly favors zincs and bonding over boats without zincs for large wood boats kept in the water 24/7/365. There are probably 100s of 1000s of 25-50 yr old wood boats that haven't shown electrical damage to the wood and 99% of them used zincs and a lessor amount with correct bonding. What do the SAMS and NAMS surveyors say about not using zincs on wood boats? Not arguing or debating, just curious.
    Chris mcm has had a lot to say before:
    Electrolysis In Wooden Boats

    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  21. #21

    Default Re: Galvanic corrosion

    Hello Bill
    Yes, with respect, what you say is what most people say. Wooden Boat and the Professional boat builder Magazine have had articles on this issue. A lot of surveyors world wide are changing their stance due to seeing evidence. Perfectly good wood boats ruined due to bonding and anodes. You may like to read http://www.dtic.mil/dtic/tr/fulltext/u2/782485.pdf and see what '' Forest Products Laboratory. US Dept of Agriculture say. see page 3-5 This is not some thing I dream't up but parallel to my experience. I just try to get the message through to Wood boat owners in NZ. I am curious to know how the chemical that does the wood damage is initiated.

    Quote Originally Posted by BillP View Post
    I don't know what it is but there's something missing and too many variables in the formula that says "no zincs" on wood boats for me to go that route. Empirical evidence highly favors zincs and bonding over boats without zincs for large wood boats kept in the water 24/7/365. There are probably 100s of 1000s of 25-50 yr old wood boats that haven't shown electrical damage to the wood and 99% of them used zincs and a lessor amount with correct bonding. What do the SAMS and NAMS surveyors say about not using zincs on wood boats? Not arguing or debating, just curious.

  22. #22
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    Default Re: Galvanic corrosion

    Looks to me, from your graph that you would e best off using only silver screws.
    Yeah, and who said boating was an expensive hobby?!!
    Now is a good time!


    Steward of MAKOTO [WB Magazine #232], and Honored Member of the LPBC

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    Default Re: Galvanic corrosion

    Salt water can easily be electrolyzed in to NaOH.

    https://www.wikihow.com/Make-Sodium-...ide-Chemically

    The NaOH will then attack the lignin in the woodland destroy the boat.

    Now, this takes a lot of NaOH, and assumes limited water circulation around the boat (which would otherwise dilute the NaOH. But it DOES happen.

    Bonding is an interesting discussion. There is a big difference between putting zincs on exposed metal pairs on a boat (prop shaft, rudder, etc), and bonding the boat. A zinc on a prop shaft will assure that the corrosion that takes place occurs on the zinc instead of the stainless prop shaft. Similarly for a stainless or bronze rudder.

    Almost all electrolysis occurs because of currents from one place to another. Usually these are a result of improper grounding. In a "hot" marina, for example, you may find boats or shore power with improper grounds, reverse polarity wiring, etc. These will provide a source (or sink, depending), for currents to flow in the water. You may have a fully bonded and zinc protected boat, but if you are near one of these other elements, you are really just feeding the beast by providing a great current path. In a hot marina, your zincs can disappear in months!, even if your boat is otherwise properly grounded.

    Dissimilar metals on the same boat will do, generally the same thing. However, they will do it even more if they are connected within the boat by a bonding system. The minute you connect all of the exposed metal together, you create a new circuit. A bronze thru hull over at the front end of the boat will not do much sitting by itself, since it is not connected to the boat ground, so there is no (low resistance) current path from the fitting to any other part of the boat. Connect it internally to the other fittings, and any differences in their galvanic potential will now result in conducted currents, and electrolytic corrosion.

    BTW, the only good way to guard against the hot marina problem is to use either an isolation transformer (so the boat ground is electrically separated from the shore ground), or to use a galvanic isolator. Isolation transformers are big, heavy and expensive. Galvanic isolators are cheap and small. The Galvanic isolator introduces about a 1-1.5 volt drop in both directions (it is made of large diodes). This drop is greater than the potential offsets from galvanic potential (see the graph at the start of this thread), and so the currents cannot flow. It's a simple $100 solution.

    Scott
    Now is a good time!


    Steward of MAKOTO [WB Magazine #232], and Honored Member of the LPBC

  24. #24
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    Default Re: Galvanic corrosion

    Wow!
    This whole thing goes way deeper than I at first expected. But maybe it will not affect me so much because it seems that you need salt water to create the battery.
    So what about fresh water? My boat will always be in fresh water.....unless I win the lottery and move to Florida or something.
    Good discussion. Thanks.
    Tim

  25. #25
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    Default Re: Galvanic corrosion

    I don't know what a Ninigret is, but if it's a small boat, kept on a trailer and used in fresh water, don't worry about galvanic corrosion. Spend your time making good supports on the trailer, and soft suspension. On bigger boats in fresh water, zinc, but don't bond. And avoid shore power.

  26. #26
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    Default Re: Galvanic corrosion

    Quote Originally Posted by timo4352 View Post
    Wow!
    This whole thing goes way deeper than I at first expected. But maybe it will not affect me so much because it seems that you need salt water to create the battery.
    So what about fresh water? My boat will always be in fresh water.....unless I win the lottery and move to Florida or something.
    Good discussion. Thanks.
    Tim
    Almost a non-issue. As Phil said, a fresh water boat that lives on a trailer won't have much to worry about. Ninigret is http://www.atkinboatplans.com/Oar/Ninigret.html

    You need some salt for galvanic corrosion, and all natural water has some salt, so you will have some galvanic corrosion, but normally a lot less. Fresh (drinking) water has <500 mg of dissolved solids per liter. Seawater has 35,000 mg per liter. An outboard with an aluminum housing and a stainless prop will still need an anode, but you need to use an aluminum or magnesium anode in fresh water. Never use Mg in salt water. Zinc doesn't always work in fresh water. Aluminum works anywhere.

    Stainless steel will not corrode unless you exceed certain temperature and salinity thresholds, which is why folks in the Baltic can use it and folks in Florida can't. If you want to find galvanic corrosion in fresh water, you could go to Duluth, and I think maybe somewhere on the Keweenaw Peninsula where there is some copper ore dust in the water.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  27. #27
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    Default Re: Galvanic corrosion

    Stainless steel will not corrode unless you exceed certain temperature and salinity thresholds,
    Or, deprive it of oxygen.

    Worth noting that corrosion comes in several forms.

    Kevin
    There are two kinds of boaters: those who have run aground, and those who lie about it.

  28. #28
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    Default Re: Galvanic corrosion

    Quote Originally Posted by Breakaway View Post
    Or, deprive it of oxygen.

    Worth noting that corrosion comes in several forms.

    Kevin
    Crevice corrosion under anoxic conditions is still strongly influenced by salinity. But there is always microbially influenced corrosion.
    https://link.springer.com/article/10.1007/BF02835718
    https://sassda.co.za/stainless-steel-and-corrosion/
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  29. #29
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    Default Re: Galvanic corrosion

    I am with Oldad.
    Use fastenings to hold the timbers together only so the epoxy dries, then remove and throw away.
    This Woolley 30 footer does not have one screw in it - all epoxy glued.
    Your wooden hull should be all epoxy fastened with no metal in it. Pict0013.jpg
    Use polymer based skin fittings (nylon based marelon) and a carbon fibre shaft tube and rudder tube if inboard.
    The only metal in the water will be the SS prop shaft and rudder shaft and the bronze alloy prop and rudder, if an inboard.
    An outboard should be lifted out of the water when left. Note an outbopard has its own anode fitted but they use low grade alloys.
    Do not let me talk about stern drives.....

    Remember Atkins drew that hull many years ago before we had folk like Gougeon Brothers demonstrating how good epoxy really was.
    Atkins relied on metal fastenings, you do not have to.
    Suggest you read Gougeons on Boat Construction -https://www.westsystem.com/wp-content/uploads/GougeonBook-061205-1.pdf
    Keep us posted on the build.

  30. #30

    Default Re: Galvanic corrosion

    Nice looking work you have done. I agree with all you say. But don't spoil it by using carbon tube. Carbon is a conductor and all marine metals are anodic to carbon. Sure it is encapsulated in resin but still conducts electricity. You can check that out yourself. Make your self a fiberglass tube using West System Resin and glass cloth.
    Quote Originally Posted by Don MacLeod View Post
    I am with Oldad.
    Use fastenings to hold the timbers together only so the epoxy dries, then remove and throw away.
    This Woolley 30 footer does not have one screw in it - all epoxy glued.
    Your wooden hull should be all epoxy fastened with no metal in it. Pict0013.jpg
    Use polymer based skin fittings (nylon based marelon) and a carbon fibre shaft tube and rudder tube if inboard.
    The only metal in the water will be the SS prop shaft and rudder shaft and the bronze alloy prop and rudder, if an inboard.
    An outboard should be lifted out of the water when left. Note an outbopard has its own anode fitted but they use low grade alloys.
    Do not let me talk about stern drives.....

    Remember Atkins drew that hull many years ago before we had folk like Gougeon Brothers demonstrating how good epoxy really was.
    Atkins relied on metal fastenings, you do not have to.
    Suggest you read Gougeons on Boat Construction -https://www.westsystem.com/wp-content/uploads/GougeonBook-061205-1.pdf
    Keep us posted on the build.

  31. #31

    Default Re: Galvanic corrosion

    As you know I have encouraged the subject of bonding and anodes. I know from experience bonded wooden boats with anodes will show signs of deterioration in two years, be very sick in ten years and if neglected be beyond economical repair in twenty years. Many can't believe I am right and more so as I don't have a degree in corrosion engineering. It seems Fifty odd years practical experience as a boatbuilder don't count. I have had people coming to me in tears wanting answers. Sadly there are none that a boat owner can understand. There are so many opinions out there , they just get confused. I have tried to help with my posting on the NZ site https://waitematawoodys.com/2015/05/...f-leaky-homes/ The same has been read all over the world, so I hope I am right. I am only a messenger, It is certainly not my theory but parallel to my experience.
    Anyway Cogeniac, I believe you are right but can I make some points.
    There is limited circulation around the cathode as part of it is embedded in wet wood. MN Dave on this post talks about the PH of the water, this is something I had neglected. Thank you Dave. It seems that the PH is increased by the current So on a bonded boat we have a partly enclosed negative cathode. The current from the dissimilar metals increases the alkalinity around the protected metal and the resulting chemical is trapped. Over time it builds up pressure and starts oozing out. You can see it on all old wet bonded boats. It is however, a very slow process. Increase the voltage to over 1.23 volts by a DC current and you will visibly see the hydrogen gas bubbles. That proves to me that bonding is extremely dangerous on a wooden boat. A 12 volt positive leak to a bonding wire can sacrifice even marine bronze. I invite comments.
    Thank you.
    Just one more thing. Bonding and Anodes is fine on a GRP boat. It allows the manufacturer to use Copper Zinc alloys for underwater components . These alloys are less expensive but it becomes the boatowners responsibility and expense to replace Anodes every year. The boat manufacturer has to save costs to remain cost competitive. I say this because wooden boats are a minority and few people know very much about them. Thus the bonding anode confusion.


    Quote Originally Posted by Cogeniac View Post
    Salt water can easily be electrolyzed in to NaOH.

    https://www.wikihow.com/Make-Sodium-...ide-Chemically

    The NaOH will then attack the lignin in the woodland destroy the boat.

    Now, this takes a lot of NaOH, and assumes limited water circulation around the boat (which would otherwise dilute the NaOH. But it DOES happen.

    Bonding is an interesting discussion. There is a big difference between putting zincs on exposed metal pairs on a boat (prop shaft, rudder, etc), and bonding the boat. A zinc on a prop shaft will assure that the corrosion that takes place occurs on the zinc instead of the stainless prop shaft. Similarly for a stainless or bronze rudder.

    Almost all electrolysis occurs because of currents from one place to another. Usually these are a result of improper grounding. In a "hot" marina, for example, you may find boats or shore power with improper grounds, reverse polarity wiring, etc. These will provide a source (or sink, depending), for currents to flow in the water. You may have a fully bonded and zinc protected boat, but if you are near one of these other elements, you are really just feeding the beast by providing a great current path. In a hot marina, your zincs can disappear in months!, even if your boat is otherwise properly grounded.

    Dissimilar metals on the same boat will do, generally the same thing. However, they will do it even more if they are connected within the boat by a bonding system. The minute you connect all of the exposed metal together, you create a new circuit. A bronze thru hull over at the front end of the boat will not do much sitting by itself, since it is not connected to the boat ground, so there is no (low resistance) current path from the fitting to any other part of the boat. Connect it internally to the other fittings, and any differences in their galvanic potential will now result in conducted currents, and electrolytic corrosion.

    BTW, the only good way to guard against the hot marina problem is to use either an isolation transformer (so the boat ground is electrically separated from the shore ground), or to use a galvanic isolator. Isolation transformers are big, heavy and expensive. Galvanic isolators are cheap and small. The Galvanic isolator introduces about a 1-1.5 volt drop in both directions (it is made of large diodes). This drop is greater than the potential offsets from galvanic potential (see the graph at the start of this thread), and so the currents cannot flow. It's a simple $100 solution.

    Scott
    Last edited by Chris mcm; 11-11-2018 at 05:28 AM.

  32. #32
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    Default Re: Galvanic corrosion

    Quote Originally Posted by Chris mcm View Post
    Nice looking work you have done. I agree with all you say. But don't spoil it by using carbon tube. Carbon is a conductor and all marine metals are anodic to carbon. Sure it is encapsulated in resin but still conducts electricity. You can check that out yourself. Make your self a fiberglass tube using West System Resin and glass cloth.
    I have just checked my records and Chris you are absolutely right - the shaft and rudder stock logs are fibreglass (not carbon fibre).
    Not sure what I was thinking.
    But the clear lesson is you can build a boat with modern materials and reduce the metals in the water to very very few.

  33. #33
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    Default

    Quote Originally Posted by MN Dave View Post
    Crevice corrosion under anoxic conditions is still strongly influenced by salinity. But there is always microbially influenced corrosion.
    https://link.springer.com/article/10.1007/BF02835718
    https://sassda.co.za/stainless-steel-and-corrosion/


    HFS!!!

    Wasn't aware of that one!


    Kevin


    Sent from my iPhone using Tapatalk Pro
    There are two kinds of boaters: those who have run aground, and those who lie about it.

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