We bought our H30 this past summer... during the survey haul-out, we replaced the zincs on the drive shaft and noted some small rust spots on the wing keel. (The boat was in saltwater for 10 years prior to purchase.) We put it back in for only two months before moving it to the freshwater Columbia River. We trucked it down I-5 and just before putting her back in, we noticed that those two month old zincs looked like 2 year old zincs. The spots on the keel had multiplied 2 or 3 times... I checked both the AC and DC electrical systems to ensure there was no path to ground... it was good. I am suspecting the VHF as this is the only way for any energy to get to the keel (through the mast). Possibly it could have been someone elses problem in the next slip, but I am open for suggestions...!!!!????
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Dave
anodes and cathodes
the process at work is one of potentials. Your zincs in this case have a higher electric potential than some other electrically active area and atoms are moving across the current path to reach the lowest energy state for the system. This is identical to an electroplating process like is used to chrome plate and so forth. You can actually have a path from the zinc anodes to thru hulls on your own boat if the thru hulls are at a lower energy state and acting as a cathode. Corrosion can take place within the same piece of metal due to electric potentials that develop in regions of the metal of different composition such as alloying elements and so forth. The salt water acts as the conductor and you can have atomic transferrence within the same part. search on the web and you will see a lot of interesting papers on this subject. One test might be to remove your batteries so the boat has no power source at all and see what happens. If the problem still exists it is the marina and not your boat most likely.
the process at work is one of potentials. Your zincs in this case have a higher electric potential than some other electrically active area and atoms are moving across the current path to reach the lowest energy state for the system. This is identical to an electroplating process like is used to chrome plate and so forth. You can actually have a path from the zinc anodes to thru hulls on your own boat if the thru hulls are at a lower energy state and acting as a cathode. Corrosion can take place within the same piece of metal due to electric potentials that develop in regions of the metal of different composition such as alloying elements and so forth. The salt water acts as the conductor and you can have atomic transferrence within the same part. search on the web and you will see a lot of interesting papers on this subject. One test might be to remove your batteries so the boat has no power source at all and see what happens. If the problem still exists it is the marina and not your boat most likely.
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Dale Ellard
Electrolysis 101
Assuming you've disconnected the battery for a time, to eliminate the possibility of outside power finding its way to your boat; Chapter 4 of Nigel Calder's "Boat Owner's Mechanical
Assuming you've disconnected the battery for a time, to eliminate the possibility of outside power finding its way to your boat; Chapter 4 of Nigel Calder's "Boat Owner's Mechanical
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Tom
It could also be the marina that you are at
If the AC wiring or the boats wired near you in the marina are not wired up correctly it can effect the electrolysis on your boat...
If the AC wiring or the boats wired near you in the marina are not wired up correctly it can effect the electrolysis on your boat...
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Aldo Lozano
Mixing oranges...
Tony, I think you are a little confused as what is what, related to electrolisys, since you are making references to a galvanic action if yours zincs are involved. Galvanic action is self-induced and mainly take place between dissimilar metals, salt water normally acting as the conductor or path between them. Electrolisys, in the other hand, results from electrical currentes seeking a path to ground. As a previous poster sugested, a reading of the differences and remedies may help you to understand better what may be your problem. If you want to pursue further the topic and/or get others sources of info, you can contact me at "alozano@monmouth.com". One big difference just to keep in mind: galvanic action are destructive. Electrolisys, it is also, plus can be lethal.
Tony, I think you are a little confused as what is what, related to electrolisys, since you are making references to a galvanic action if yours zincs are involved. Galvanic action is self-induced and mainly take place between dissimilar metals, salt water normally acting as the conductor or path between them. Electrolisys, in the other hand, results from electrical currentes seeking a path to ground. As a previous poster sugested, a reading of the differences and remedies may help you to understand better what may be your problem. If you want to pursue further the topic and/or get others sources of info, you can contact me at "alozano@monmouth.com". One big difference just to keep in mind: galvanic action are destructive. Electrolisys, it is also, plus can be lethal.
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Don Alexander
Galvanic Isolator
Tony, If you leave your boat plugged into a marina supply you can be a part of a much larger circuit and possibly be the sacrificial part. The best way to overcome this is with an isolating transformer, but these are large, quite expensive and very heavy. Accordingly Galvanic Isolators are made which isolate your boat from earth leakages in marinas etc, but these only keep small potentials at bay. However they are claimed to be effective. Regards,
Tony, If you leave your boat plugged into a marina supply you can be a part of a much larger circuit and possibly be the sacrificial part. The best way to overcome this is with an isolating transformer, but these are large, quite expensive and very heavy. Accordingly Galvanic Isolators are made which isolate your boat from earth leakages in marinas etc, but these only keep small potentials at bay. However they are claimed to be effective. Regards,
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Tom
Galvanic Isolator -- Heavy ! ?
While I agree w/ everything you said ...I really don't think the Galvanic Isolator is very heavy....I have a '99 C36MKII and they have one installed from the factory. It really isn't that big. It is made by Professional Mariner (Though other manufacters make them....Pro Mariner link is added below take a look) and you can purchase through quite a few marine catalog companies....(they also have a reason to on a boat because of the saftey factor) I think in the old days they used to be heavy because they were made via big windings of wire and achieved isolation via electromagnetic means....these days they are made with electronic circuits and that is the reason for the loss of weight. Guest makes one also and it is only 3.5 pounds..to look it up go here http://www.chargepro.com/galvanic.html Or you *could* make your own... for instruction and info go here http://www.yandina.com/electrolysis.htm
While I agree w/ everything you said ...I really don't think the Galvanic Isolator is very heavy....I have a '99 C36MKII and they have one installed from the factory. It really isn't that big. It is made by Professional Mariner (Though other manufacters make them....Pro Mariner link is added below take a look) and you can purchase through quite a few marine catalog companies....(they also have a reason to on a boat because of the saftey factor) I think in the old days they used to be heavy because they were made via big windings of wire and achieved isolation via electromagnetic means....these days they are made with electronic circuits and that is the reason for the loss of weight. Guest makes one also and it is only 3.5 pounds..to look it up go here http://www.chargepro.com/galvanic.html Or you *could* make your own... for instruction and info go here http://www.yandina.com/electrolysis.htm
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Peter Albright
Galvanic Isolators, in the perfect world
In a perfect masrina, with a perfect electrical system, and perfect boats: The ground and neutral are only connected at the utility transformer and the marina main service (assuming a 120 volt service). No one has leaky equipment, and no currect flows in the ground circuit. No one has any AC problems, except for short circuits that trip breakers. Two boats plugged into shore power, with bonded thru hull connections, have a direct path from boat to boat. A galvanic circuit is then created between dissimilar metals, and one of the boats can become the sacificial anode. A galvanic isolator put a nominal 1.4 volt blockage in the ground connection, which is larger than the voltage difference of the dissimilar metals. AC short circuits will not notice the 1.4 volt drop, and the circuit breaker should trip before the diodes fail open. This is great in a perfect world
In a perfect masrina, with a perfect electrical system, and perfect boats: The ground and neutral are only connected at the utility transformer and the marina main service (assuming a 120 volt service). No one has leaky equipment, and no currect flows in the ground circuit. No one has any AC problems, except for short circuits that trip breakers. Two boats plugged into shore power, with bonded thru hull connections, have a direct path from boat to boat. A galvanic circuit is then created between dissimilar metals, and one of the boats can become the sacificial anode. A galvanic isolator put a nominal 1.4 volt blockage in the ground connection, which is larger than the voltage difference of the dissimilar metals. AC short circuits will not notice the 1.4 volt drop, and the circuit breaker should trip before the diodes fail open. This is great in a perfect world
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Tom
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Peter Albright
Isolation Transformers, for the real world.
In the real world, with multiple ground to neutral connections, illegal marina wiring, high resistance terminations, and boat owners with 25 wires on the positive battery terminal (I bought one): Neutrals and grounds have multiple connections, and there are high resistance shorts to ground and high resistance netral connections. All of these cause current to flow in the "ground path". The "ground path" is every conducting material between the problem and the utility transformer. If someone connects the green and white AC wires in his boat, the current could decide to use the ground, instead of the neutral. It could decide to go out his prop shaft, in your prop shaft, and take most of your boats metal with it. Isolation transformers solve both galvanic and AC wiring problems. For a 30 amp connection, you are fine with a 3 kVA transformer. It will weight about 60 lbs, cost under $200 if you try hard, and will need a 2 pole GFCI primary breaker to complete the installation. You will have NO connection between your boat and shore power (Ok, some capacitive coupling). With a properly installed isolation transformer, the only AC electrical problems on your boat will be your own, and they will stay on your boat. With GFCI breakers or receptacles, you will have no problems, or no electricity. Your only outside susceptibility is stray current between bonded thru hull connections (another subject).
In the real world, with multiple ground to neutral connections, illegal marina wiring, high resistance terminations, and boat owners with 25 wires on the positive battery terminal (I bought one): Neutrals and grounds have multiple connections, and there are high resistance shorts to ground and high resistance netral connections. All of these cause current to flow in the "ground path". The "ground path" is every conducting material between the problem and the utility transformer. If someone connects the green and white AC wires in his boat, the current could decide to use the ground, instead of the neutral. It could decide to go out his prop shaft, in your prop shaft, and take most of your boats metal with it. Isolation transformers solve both galvanic and AC wiring problems. For a 30 amp connection, you are fine with a 3 kVA transformer. It will weight about 60 lbs, cost under $200 if you try hard, and will need a 2 pole GFCI primary breaker to complete the installation. You will have NO connection between your boat and shore power (Ok, some capacitive coupling). With a properly installed isolation transformer, the only AC electrical problems on your boat will be your own, and they will stay on your boat. With GFCI breakers or receptacles, you will have no problems, or no electricity. Your only outside susceptibility is stray current between bonded thru hull connections (another subject).
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Peter Albright
Tom, no
They work fine for galvanic voltages. They don't provide protection for AC wiring faults, which can sink you much faster than the guy with no zincs.
They work fine for galvanic voltages. They don't provide protection for AC wiring faults, which can sink you much faster than the guy with no zincs.
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Tom
Peter...Ok...yes that does make sense...
But I don't think I am going to put that on my boat....I do have a warning led on my boat that should brighten up if there is voltage difference between nuetral and ground (which should at least alert me to a problem).....then it's up to me to track it down... Are you away of the LED they put on the newer Catalinas for this purpose.....what are your thoughts?
But I don't think I am going to put that on my boat....I do have a warning led on my boat that should brighten up if there is voltage difference between nuetral and ground (which should at least alert me to a problem).....then it's up to me to track it down... Are you away of the LED they put on the newer Catalinas for this purpose.....what are your thoughts?
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Peter Albright
Second best choice
The led will indicate a reversed hot and neutral, and is required if all the AC breakers do not break both poles. The next best thing to an isolation transformer, is a 2-pole GFCI main breaker. If you ever add the transformer, you'll need it anyway. Don't change your AC panel, install the GFCI ahead of it. To install, don't use the neutral wire on the breaker, cap it off. run both the hot and neutral legs through the breaker. This will disconnect both if there is a problem. If you do not have an isolation transformer, a galvanic isolator should be installed.
The led will indicate a reversed hot and neutral, and is required if all the AC breakers do not break both poles. The next best thing to an isolation transformer, is a 2-pole GFCI main breaker. If you ever add the transformer, you'll need it anyway. Don't change your AC panel, install the GFCI ahead of it. To install, don't use the neutral wire on the breaker, cap it off. run both the hot and neutral legs through the breaker. This will disconnect both if there is a problem. If you do not have an isolation transformer, a galvanic isolator should be installed.
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