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Old 26-12-2017, 19:23   #1
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How do you prevent electrical corrosion in a marina

Hi

I am busy completing building a catamaran. Apparently there are electrical problems in the marina. I am new to sailing and want to hear how does one protect ones sail drives and propellers. I have ordered an anti corrosion management system from the US.
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Old 26-12-2017, 19:29   #2
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Re: How do you prevent electrical corrosion in a marina

there are three solutions. In increasing order of effectiveness:

3.) Install a "zinc saver" also called a galvanic isolater. This prevents low level DC currents from being carried by your ground wire.

2.) Install an isolation transformer. This completely isolates the boat's electrical system from the shore power.

1.) Don't plug into shore power.
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Old 26-12-2017, 19:29   #3
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Re: How do you prevent electrical corrosion in a marina

Step one is isolation transformer.
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Old 27-12-2017, 05:05   #4
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Re: How do you prevent electrical corrosion in a marina

Yeah if it's a hot marina and many of them are, shore power is bad to stay plugged Into. We were replacing the split zincs at 3 to 4 months. Away from a "hot"marina we can go a year.
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Old 27-12-2017, 05:24   #5
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Re: How do you prevent electrical corrosion in a marina

i donot use isolation transformer nor galvanic isolator since my system had fail in sd. however, my zincs last me 1.5 years due to my electrical system on board not having any stray current. imagine that. a zinc lasting 1.5 years. must be magic. yes my zincs are checked monthly. i recently replaced my trawler plates which had not needed replacement since before 2008, when i bought this boat.
pure magic.
funny was barra de navidad's isla marina, which has been reported as a hot marina.. funny. same marina mazatlan.
i guess chebio, in cihuatlan, is the best ever boat electrician. before he touched my electrickery i was going thru zincs every 3 to 4 months.
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Old 27-12-2017, 07:03   #6
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Re: How do you prevent electrical corrosion in a marina

Quote:
Originally Posted by zeehag View Post
i donot use isolation transformer nor galvanic isolator since my system had fail in sd. however, my zincs last me 1.5 years due to my electrical system on board not having any stray current. imagine that. a zinc lasting 1.5 years. must be magic. yes my zincs are checked monthly. i recently replaced my trawler plates which had not needed replacement since before 2008, when i bought this boat.
pure magic.
funny was barra de navidad's isla marina, which has been reported as a hot marina.. funny. same marina mazatlan.
i guess chebio, in cihuatlan, is the best ever boat electrician. before he touched my electrickery i was going thru zincs every 3 to 4 months.


All that means is that he disconnected your AC electrical ground from anything onboard your boat other than the shore cord. Not the safest thing to do, now you’re relying on the marina wiring to be properly grounded.
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Old 27-12-2017, 08:32   #7
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Re: How do you prevent electrical corrosion in a marina

I installed this on my last boat with a sail drive and it was the best investment I have made on a boat. Never had to replace my zincs on the sail drive and never had to worry about a hot harbor.

Electro-Guard, corrosion and cathodic protection specialists for boats, yachts and small ships.

Gary
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Old 27-12-2017, 08:35   #8
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Re: How do you prevent electrical corrosion in a marina

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All that means is that he disconnected your AC electrical ground from anything onboard your boat other than the shore cord. Not the safest thing to do, now you’re relying on the marina wiring to be properly grounded.
i have 2 separate systems, one for 120 which here is 137v, and one for 12 v, each complete. we are re-wiring boat and creating new panels.
my cihuatlan electrickery man was electrician on shrimpers for over 30 years, along with my engine rebuilder and fuel pump builder.
they adore me and donot wish me to burn to waterline. more than can be said for most electricians on planet about their clientelle.
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Old 27-12-2017, 08:45   #9
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Re: How do you prevent electrical corrosion in a marina

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...
they adore me and donot wish me to burn to waterline. more than can be said for most electricians on planet about their clientelle.
I like your sense of humor. electrickery and all.
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Old 27-12-2017, 09:45   #10
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Re: How do you prevent electrical corrosion in a marina

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All that means is that he disconnected your AC electrical ground from anything onboard your boat other than the shore cord. Not the safest thing to do, now you’re relying on the marina wiring to be properly grounded.
It is actually the thing you should do: NOT using shore power earthing to earth the boat. The shore power earthing cable is not necessarily at the same voltage (zero) as the (zero) of the water you are floating in. By connecting this earthing cable to your on board earth you connect the hull, rudder, propeller shaft and so on with "shore zero". You actually impress a current on these items when land-zero is not water-zero, consequently eating your anodes in the best case or a whole aluminium hull in the worst case. Installing an isolation transformer is a nice solution separating all three wires, but it does not improve safety over only isolating ships earth from the shore earth. One should have ship earth earthed to the water you are floating in by means of prop shaft or even a dedicated earthing plate in a glass boat. With your on-board safety device in the form of earth leak circuit breaker on the AC side in your boat you are protected.
This is the way the wiring should be done: Ships earth is NOT land earth. Known hot marinas clearly have a known difference between their zero and the water. Only needs a few tenth of a Volt to create the problem. Cut that green/yellow wire at the connection point on the boat. Now the cable is earthed to the shore and protected by the marina's earth leak circuit breaker while your side is protected by the on board installation.
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Old 27-12-2017, 10:21   #11
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Re: How do you prevent electrical corrosion in a marina

Just a suggestion. If spending the money for an isolation transformer go for a buck/boost transformer. If at a marina with lousy low voltage you can jack it up.
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Old 27-12-2017, 10:42   #12
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Re: How do you prevent electrical corrosion in a marina

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Originally Posted by billknny View Post
there are three solutions. In increasing order of effectiveness:

3.) Install a "zinc saver" also called a galvanic isolater. This prevents low level DC currents from being carried by your ground wire.

2.) Install an isolation transformer. This completely isolates the boat's electrical system from the shore power.

1.) Don't plug into shore power.
Agree.

Measuring the boats potential to surrounding water with a meter and reference electrode gives me peace of mind. I took off my transformer and installed a 100 watt solar panal. I sometimes wonder why the barnacles pounce on the zincs which can reduce the effectiveness. Maybe zinc tastes better. It good for the immune system anyway.
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Old 27-12-2017, 12:49   #13
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Re: How do you prevent electrical corrosion in a marina

You have received a lot of good advice, however if the marina wiring is incorrect or if you have a hot boat next to you the ONLY way to protect yourself is with properly installed zincs and a good bonding system on YOUR boat. Staying off shore power will definately help but it will not cure the problem! Be careful diving on your boat!!!
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Old 27-12-2017, 15:09   #14
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Re: How do you prevent electrical corrosion in a marina

I simply used an isolator to keep the shore power separate from the AC used on the vessel. The best ones are transformers. They are heavy. If you run an air conditioner it weill have to be a biggie. They are not cheap either unless you can get one from a disposals store.

Never connect your earth system to a marina earth system. That is making your vessel the most likely best earth--with all stray currents and voltage inequalities from the entire marina going to YOUR boat and hence to ground--taking your zinc anodes, the lead from your keel and any aluminium and anything else with it.

It is astonishing how much metal one milliamp of stray current can move in one year.
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Old 27-12-2017, 20:08   #15
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Re: How do you prevent electrical corrosion in a marina

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Originally Posted by Fuegomar View Post
Agree.

Measuring the boats potential to surrounding water with a meter and reference electrode gives me peace of mind. I took off my transformer and installed a 100 watt solar panal. I sometimes wonder why the barnacles pounce on the zincs which can reduce the effectiveness. Maybe zinc tastes better. It good for the immune system anyway.

To a barnacle, maybe it's like a warm foot bath or a tanning bed...

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