How do I save my ZINCS?

[Kim Beatley]

Had to haul boat this week for insurance survey, just six weeks from splashing with new bottom job and new zincs. To my surprise, shaft zincs were half gone.

Can someone provide advice on Galvanic Isolators? Or, provide other suggestions that may extend life of zincs. Note, I have visuall inspected engine room electrical and all looks in order. Boat is connected to 50 AMP shore power 24/7, but that system is fairly new as well. Advice welcome!!

 

[magnawake]

I have the same problem with the exception that mine last 7 months. People next to you may have power cords laying in the water or they have a electrical problem too. All this adds up to the zincs being eaten up. The diver in the marina we used to be at said 6-8 months is normal for our marina. I even dropped a zink fish with a cable on it to try to prolong the life of my zincs. I think it helped some after I clipped it on. It must be grounded as well. Some waters have heavy elecrolisis (spelling) than others. Ir depends on lots of things. I'm no expert on the subject though....

 

[bostonhatteras]

Ground, ground, ground! That's your answer. Zincs main job is to control GALVANIC corrosion. That's when the electrical potential of dissimilar metals cause a battery type situation between them, one losing electrons to supply the other. Zincs that deplete as fast as yours are surely caused be electrolysis which is higher voltage being pumped into the water somewhere somehow. ELECTROLYTIC corrosion is what is depleting your zincs. Your electrical system may look fine from a simple look over but the key is to ensure that every electrical item has a clean and easy way to return the electricity to the battery or shore power source. If they don't they will find the easiest way and that may be through your propellers to another boats propellors to his grounding system and then to ground! Could be your boat with the problem, could be the dock, could be another boat. The galvanic isolator cuts the passing potential of the grounding line back to the dock so that it can only pass large amounts that would kill people. You should have at least a galvanic isolator on each shore power line, or pony up the big bucks and go with isolation transformers that do a fair amount more. Take an ohm meter and clamp on one test lead on the disconnected positive battery clamp and go through and see where you find high readings. This will be where you are leaking electricity. Shore power can be done the same way. Disconnect the shore power line. Clamp one test lead onto the hot spade or on the back of the shore power receptacle and go through touching all metal objects and note the readings. High readings will show a connection between metal and powered cables. You can check the integrity of the bonding system the same way. This time though all bonded metals should show a direct connection not low readings.

 

[Boatnut]

If you aren't familiar with using electrical test equipment, and other do dads associated with checking out this problem, your best bet may be to hire a good qualified marine electrician, emphasis on good. The amount you may have to pay him is peanuts compared to future costs associated with electrolysis. If you have owned the boat for a while and did not have this problem in previous marinas, there is a good chance the marina is hot, or another boat as previously mentioned, not an uncommon situation. Look around the marina at the wiring in the marina, are there any runs of wire in the water, do other boats have wires hanging in the water, and if you see anyone using automobile battery chargers, shoot them, (just kidding), automobile battery chargers are big cause of problems, as they are not isolated.

 

[petohazy]

I had an Impressed Current system and monitor installed on one of my previous boats. Completely eliminates the need for zincs. Our system worked so well, I'm thinking about adding a system to our boat next time its hauled. A great piece of mind and cost savings (no more zincs!), knowing you never have to worry about zincs again.

 

[dsharp]

Are you running a battery charger constantly to keep the batteries up? professional Boatbuilder ran an article on the subject. I will see if I can find it. That sentence was not very clear. The article was about the bonding system and zincs. From past experience the old constavolt chargers were not isolated very well.

 

[Jaxfishgyd]

When I first moved our 'home' to Fernandina Beach, I suddenly was going thru zincs at the rate of every 3 months... We found the problem was coming from the dock 200' from us, that had 4 boats there.... Luckily they were close down due to no permit to rent space out..
My zincs now last 9-10 months before replacing

 

[Kim Beatley]

I just replaced batter charge with a ProMariner 1250P unit. All new wiring/connections and fuses.

This afternoon I pulled the pannel which hids the wiring where the shore power enters the boat. What a corossion mess. Will order new 30 amp plugs tomorrow and replace. Will pull wiring and replace if needed.

Tell me more about impressed current systems. Is there a good brand/unit on the market? All I see on the net are untis for large steel ships.

 

[petohazy]

Tell me more about impressed current systems. Is there a good brand/unit on the market? All I see on the net are untis for large steel ships.

The unit I had on my 48 was made by CAPAC (they do make them for ships as well as smaller boats). Did a quick google search and noticed a brand called Electro-Guard. Looks like these are geared toward the recreational boat market.

 

[fissioneng]

Can someone provide advice on Galvanic Isolators?

I installed a DEI Galvanic Isolator last year after measuring DC current coming aboard the ground in my shore power cable. I'm getting 12 months plus out of my zincs now. This unit has no fan.

This only corrects one source of stray current. Another possible one is from your DC system which was already mentioned. Shorted bilge pump switches are mentioned most often as the culprits.

What happens in a marina is that when your neighbor's zincs go away due to neglect, their boat starts using yours and everyone else's zincs unless there's an isolator to prevent that. The shore power ground ties everyone who is hooked to shore power into one big zinc network. The more depleted zincs in the network, the faster yours will deteriorate.

 

[ram]

I had an Impressed Current system and monitor installed on one of my previous boats. Completely eliminates the need for zincs. Our system worked so well, I'm thinking about adding a system to our boat next time its hauled. A great piece of mind and cost savings (no more zincs!), knowing you never have to worry about zincs again.

Hi Petohazy; Was checking old forums and came across yours from last year about the Impressed
Current System and would like to ask where you bought it and how much it was. My zincs are
lasting about 7 months up here in Vancouver BC. Not bad but the system you had, I read about last week and it sounds like the way to go. The people that sell them are from England. Any info would
be appreciated. Thanks Rick

 

[Doug.T]

Check out this thread. Good relevant information.

http://www.samsmarine.com/forums/showthread.php?932-galvanic-isolators&highlight=galvanic

Doug
"Beach Girl"
'86 53MY

 

[Maynard Rupp]

We moved our boat from the Great Lakes to Miami and immediately started eating zincs. I checked all grounds. Several people recommended I install a galvanic isolator. Hatteras doesn't like them from a safety standpoint. I tried everything to no avail. I finally installed a galvanic isolator and completely solved he problem.