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Thread: Electrolysis from steel boat next to wood boat?

  1. #1
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    Default Electrolysis from steel boat next to wood boat?

    I've recently noticed some evidence of electrolysis damage to my old 42' wood power boat. I've been trying to figure out the cause with the help of the local boat yard, but nothing seems to stand out. I don't think it's necessary to go into the specific damage, but it does seem to roughly coincide with an old run-down steel houseboat that moved into the slip right next to me a few years ago. I'd like to know if anyone has had experience with any kind of electrical/electrolysis damage that occurred to a wood boat because of a steel boat docked next to it, and is there a way to test for it? Both boats are in the water year-round. I'm considering whether to move to another slip. Many thanks.

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    Default Re: Electrolysis from steel boat next to wood boat?

    Dunno on a steel boat, but an improperly wired (grounded) boat of any material can cause serious electrolysis - even electrocution of swimmers.

    Here's one story: https://www.mikeholt.com/mojonewsarc...s~20031024.htm
    "If it ain't broke, you're not trying." - Red Green

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    Default Re: Electrolysis from steel boat next to wood boat?

    I would be very surprised unless you are connected electrically to make a return circuit. Possibly by the earth wire of a shore supply?

    There has to be a potential to drive the current through your wood. If the sea provides one connection as the electrolyte of the battery, there has to be another with a low resistance to make the return leg of the circuit and metal in your boat with a different value on the galvanic scale making the other electrode.
    It really is quite difficult to build an ugly wooden boat.

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    Default Re: Electrolysis from steel boat next to wood boat?

    Do you have a disconnect device, a 'Zinc Saver' is one. These allow the Ground wire to be open under normal circumstances, but snap shut in the event of an electrical short. The ground leg connects every boat on that circuit on the dock into one big boat, so a problem with any of those boats is shared by all.
    This can be tested by someone who has a Silver-Silver Chloride reference zinc and a multimeter to see if there is any electrical potential on your shore power ground leg. Even a small milliamperes reading multiplied by 24 hours can eat zincs.
    Are any of your large metal fittings below the waterline showing any white froth or fuzz around them?

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    Default Re: Electrolysis from steel boat next to wood boat?

    I once surveyed an old (1939) wooden tug that had been tied up along side of an iron barge (it's barge) for several years, and the delignification was severe, particularly at the keelson and stern bearing. They were connected to shore power. Once the two were separated and isolated from each other (by several miles) the problem was stopped but the damage was done. The tug needs a new keelson at best.

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    Default Re: Electrolysis from steel boat next to wood boat?

    I know that there's always a difficulty for Aluminium-boats berthed next to steel-boats, but so far I've never heard of a case where a wooden boat was being affected by a steel boat next to it. Sometimes there are stray-currents in Marinas mainly caused by bad grounding or other faulty stuff of the whole electric system supplying the boats with electricity, and this produces a big impact on everything.

    How about your own electric system? 240 V (ahem, you might be 110V) and 12 V (again, you might be 24 V)? Is everything in perfect condition there? How is it set up? Have you got anodes and do you replace them regularly?

    Actually, what makes you believe there is a problem with stray-currents in your ship? Has your propshaft turned copper-coloured, are your sea-cocks desintegrating, are fasteners starting to suddenly show whitish stuff or other indications of going the wrong way in development?

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    Default Re: Electrolysis from steel boat next to wood boat?

    Would it be a valid test to connect a zinc to the ground leg of shore power, drop it into the water and see what happens to it?

    Jeff

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    Default Re: Electrolysis from steel boat next to wood boat?

    Quote Originally Posted by Paul Schweiss View Post
    The ground leg connects every boat on that circuit on the dock into one big boat, so a problem with any of those boats is shared by all.
    Thanks for the replies. I should have mentioned that the last two years I've disconnected the shore power during the 9 month off-season wet storage. I've just run in a 110v line, independent of the boats 110 wiring, to power the batt charger, so there's no ground connection between boats.

    I've been thinking along the lines that a steel boat might be more likely to put voltage in the water due to stray currents in the steel boat grounding out to the hull. This voltage in the water might then impact my boat. I did try to test for this with a regular digital voltmeter, but did not find anything. However, I don't know if I'm testing correctly - I attached the neg lead of the voltmeter to the shore current ground and put the pos lead in the water. I'm not an expert on electrical.

    As I mentioned, I don't see the need to complicate the issue with specifics about my damage. I'm just asking if anyone has experience or knowledge of a steel boat generally being a bad idea next to a wood boat.

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    Default Re: Electrolysis from steel boat next to wood boat?

    You need to connect up with a marine electrician who can measure the potential of your hull in relation to the steel hull. This is, most often, measured in micro current flow. The steel boat should be checked to make sure that it is properly grounded.
    Jay

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    Default Re: Electrolysis from steel boat next to wood boat?

    Quote Originally Posted by Jay Greer View Post
    You need to connect up with a marine electrician who can measure the potential of your hull in relation to the steel hull. This is, most often, measured in micro current flow. The steel boat should be checked to make sure that it is properly grounded.
    Jay
    May I also suggest that other boats nearby be checked as well? A boat made from any material can have ground issues that could cause you (& others) problems.
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    Default Re: Electrolysis from steel boat next to wood boat?

    All boat owners are suspicious of their neighbors boat. Very Common.
    I have seen older wooden boats with many electrical issues mostly from bad information.
    Also if your boat bottom design is closer to the bottom at low tide you will need to take that into consideration .
    I love the smell of fresh cut plywood in the morning.

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    Default Re: Electrolysis from steel boat next to wood boat?

    Yes it can happen. May be the dock - bad GFI and general leakage - combined with the boat, of the dock alone even. I've twice been at winter docks where that was a problem. Given the bonding already on the sail boat I lived on, it was easy to wire some zincs to the shrouds and hang them over the side. To everyone's surprise, it worked.

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    Default Re: Electrolysis from steel boat next to wood boat?

    Note that any 110 volt AC line shares a neutral with every boat in the marina that is "plugged in".
    (This is effectively the same as "ground", but a separate and different wire. When you are connected to 110 ac you are then connected to every other boat in the marina that is using AC)

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    Default Re: Electrolysis from steel boat next to wood boat?

    If you're powering a battery charger with direct 110, I'd hope you're also disconnecting the battery from the boats 12V system. Otherwise, that ground/neutral is no longer isolated as it would be through properly isolated shore power wiring aboard your boat and any trickle current could be working out through your boat's ground wiring. For what it's worth, a battery charger doesn't need to be left plugged in all the time either. It could just be hooked up every few months depending on the ambient temperature and rate of battery self-discharge. Here in Maine, we generally top off batteries with decommissioning for winter and don't bother to charge them again until the spring. An extra charge or two might be appropriate down there with the warmer temps.

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    Default Re: Electrolysis from steel boat next to wood boat?

    Quote Originally Posted by Canoeyawl View Post
    ...(This is effectively the same as "ground", but a separate and different wire.
    In a 3-wire cicuit, viz., 'hot', 'neutral' and 'ground', the ground conductor during normal operation carries no current and is connected to the 'neutral' conductor at the source (far end) and the latter duo in turn, to a grounding copper rod or similar device.
    The purpose of this seemingly redundant conductor is to provide a path to ground for any fault that may occur at the consumer end; for example, a breakdown of insulation between the device consuming power (motor, heating resistance etc) and it´s casing, whereby the current through the ground wire would activate the associated circuit-breaker and de-energises the lot.

    Quote Originally Posted by Canoeyawl View Post
    When you are connected to 110 ac you are then connected to every other boat in the marina that is using AC)
    Depending on 'who has connected what to where', there could be another connection between the boats, viz., through the surrounding water.

    One way out of this is for the AC power on board to be furnished through an isolation transformer, which eliminates galvanic connection between the boats

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    Default Re: Electrolysis from steel boat next to wood boat?

    As Ian wrote it's often the marina's wiring and electrical boxes that charge the marina waters. Not many do much in the way of serious checking for leakage and subsequent maintenance, leaving problems up to individual owners' to identify and then fix themselves or leave it to the owner's insurance to address.

    http://en-us.fluke.com/community/flu...boat-dock.html

    http://www.thehulltruth.com/boating-...my-marina.html
    Last edited by rbgarr; 09-15-2017 at 02:54 PM.
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    Default Re: Electrolysis from steel boat next to wood boat?

    I once "discovered" a hot 440v ac line about the size of my thumb leading directly into the water at a local pier. There was no clue about how long it had been that way, but the nearest steel vessels were "sizzling" with a measurable loss of plating thickness.

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    Default Re: Electrolysis from steel boat next to wood boat?

    Quote Originally Posted by marujo.sortudo View Post
    If you're powering a battery charger with direct 110, I'd hope you're also disconnecting the battery from the boats 12V system. Otherwise, that ground/neutral is no longer isolated as it would be through properly isolated shore power wiring aboard your boat and any trickle current could be working out through your boat's ground wiring. For what it's worth, a battery charger doesn't need to be left plugged in all the time either.
    I've NOT been disconnecting the batt neg cable to the engine block during the storage. I'm not sure if this is what you are referring to, but it seems like it won't hurt, and I will do this for the coming storage. I thought I had been disconnecting all the 12v hot leads from the batt except for the bilge pumps, but it turns out upon closer inspection that I left the LectraSan connected, and the engine alternators. When I did a ground fault test by disconnecting the hot leads from the pos batt terminal and putting a voltmeter between them, I did get a 12v reading for both of these. I'm not sure what to make of the alternators, they are the new type that just connect with pos and neg wires to the batts with no regulators like in the old days. But Ill disconnect these as well, so that the batts are isolated completely from the boat except for the bilge pumps.

    The boat sits for 9 months while I'm in Florida, so it would be more complicated to have someone plug in the charger power every 3 months. Also, I'm running a dehumidifier for a few hours a day, so power is needed for that.

    Regarding the suggestions about a marine electrican, there's no one in my area, and it sounds expensive anyway.

    Thanks everyone for the feedback.
    Last edited by jrusk; 09-16-2017 at 03:15 PM.

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    Default Re: Electrolysis from steel boat next to wood boat?

    If you think an electrician is expensive, wait till you get to pay for a sinking because a thruhull or plumbing fitting that is the wrong alloy fails, or a new horn timber or planking is needed due to the wood being eaten by electrolysis.

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    Default Re: Electrolysis from steel boat next to wood boat?

    An article of general interest by David Pascoe, a retired Marine Surveyor with a lifetime of hands-on experience :

    http://www.marinesurvey.com/surveyguide/wood1.htm

    As the OP has not specified the (apparent) 'electrolysis' damage on his vessel, this article may help in identifying the possible cause of the reported malady.

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    Very interesting, thanks for posting this carioca!

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    Default Re: Electrolysis from steel boat next to wood boat?

    Quote Originally Posted by Dody View Post
    Very interesting, thanks for posting this carioca!

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    Your comment in regard to Nigel Calder´s book on the Petrel thread shone a light on a topic that most of us are somewhat lazy to address, although are unable to negate..... the desire of a low-maintenance outcome, besides performance enhancements, following a major rebuild/redesign.

    This prompted me to sift through your whole thread late last night......had been glossing over it, unknowingly.....your enthusiasm, goals (non-profit) and drive level are out of the ordinary !

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    Default Re: Electrolysis from steel boat next to wood boat?

    Thanks carioca !
    fair winds, Dody

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    Default Re: Electrolysis from steel boat next to wood boat?

    jrusk, Yes, I was referring to whether you were disconnecting the battery. Not just the hot leads, but also any and all paths the ground would have to water. By leaving the engine and the bilge pumps connected, you're inviting trouble to my understanding. Disclaimer, I am not a marine electrician. ANY electrical path to water needs to go through either a galvanic isolator or an isolation transformer. Otherwise, your boat will get eaten, and not because of the boat next door, but because you didn't handle electrical current correctly. If your marina or the boat next door has problems, this would make yours worse ... but you'd still be responsible for your failure to wire your boat correctly. I recommend reading Nigel Calder's books on the subject and anything else you can and if this is not something that you are sure you're competent to handle, find and hire a professional.

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    + 1!!! 👍

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