Anodes wearing out FAST

[reeltime]

Hi ,I have a Marine trader 40 ,Usually I get 12 to 18 months out of a set of Anodes. Recently moved to another marina and hauled for a wash ,the Anodes were almost completely gone in 5 months, Nothing has been changed on the boat . I asked the marina to check for stray currents but I bet they will say there wiring is ok . What do I check next ?

 

[O C Diver]

The boats next to you. Eating of anodes in a marina is often the result of a neighboring boat leaking current into the water.

Ted

 

[DavidM]

Yes adjacent boats can leak current into the water, but the bigger problems with adjacent boats is leaking current into the ground wire of their shore power which gets back to your boat and wrecks havoc with your zincs.

A shore power isolator installed on your boat can solve this. Also keeping your shore power cord disconnected will too.

You can check if you have a problem with the shore power ground with a meter but it takes some skill. A marine electrician can do it in a few minutes as well as check your boat for leakages to ground which can cause the same symptoms.

I presume that your marina doesn't have GFCIs on its shore power outlets. Marinas are slowly adding them which can be a pita but also solves the problem of other boats affecting yours.

David

 

[Bmarler]

even though you say nothing has changed on your boat, you should get someone with a silver half cell to check your underwater metals and be sure that nothing is going on with your own equipment. things can happen with your on-board electrical equipment that can cause leakage to ground.
hopefully that's not the issue, but it's good to know for sure. you'll also be able to easily see if you're having issues with the incoming shore power. then you can take that information to the marina staff.

 

[SteveK]

even though you say nothing has changed on your boat

Confession. After reading this my mind went to.....
The boat that was moored next in his previous marina is trying to figure out why his anodes are now lasting longer.

 

[syjos]

The other boats in the marina are depleting your zincs via the ground wire connecting all the boats together.

Installing a galvanic isolator on the ground wire would be one solution.

Installing an isolation transformer would be the best solution. The IT creates it's own ground so it does not use earth for ground, which elliminates other boats ground connection to your zincs.

The transformer, not having a physical connection to the incoming shore AC, alleviates reverse polarity and other AC issues on docks, prevents electrocuting swimmers and allows shore connections to ELCI equipped marinas without tripping the breaker.

My license plate zinc last 10 plus years with minimal wear. I test all underwater metal twice per year using a silver oxide probe and a multimeter.

I am a dealer for Victron isolation transformers.

 

[Iggy]

You can also use a clamp on meter to check for leakage too. It must be one that is sensitive in the mA range. You clamp it on your shore cord with everything turned on, OR mostly everything. If you read more than 20 to 30 mA you have current going somewhere else.

 

[GoneFarrell]

Iggy,
Thanks for that. I was wondering if I had to build a jumper to break out the conductors to check each branch of the circuit. I think I'll dig around on the boat side to check there too.

I may have a "problem boat" on the other side of my pedestal. It hasn't moved for over 3 years! Thinking to briefly open the breaker on that side and see if that changes anything on my side.

My marina does dockside checks at least once a year, no GFCI's. Haven't been approached by them.

 

[syjos]

Iggy,
Thanks for that. I was wondering if I had to build a jumper to break out the conductors to check each branch of the circuit. I think I'll dig around on the boat side to check there too.

I may have a "problem boat" on the other side of my pedestal. It hasn't moved for over 3 years! Thinking to briefly open the breaker on that side and see if that changes anything on my side.

My marina does dockside checks at least once a year, no GFCI's. Haven't been approached by them.

Opening the breaker only breaks the neutral and hot. The ground is still connected.

You need a break out cable. Clamping around the shore cord, all three wires, will not measure current. The clamp is placed around a single wire to measure current.

The clamp is placed around the ground wire to measure leakage in or out of your boat. I would open up the pedestal that the problem boat is plugged into and place the clamp around the ground wire in the pedestal to verify if it's the leakage offender.

The GFCI does nothing for the ground wire corrosion issues. It breaks when there is a difference between the hot and neutral amperage.

You can also disconnect the ground connection from your boats AC ground to the boats bonding to see if zinc consumption is reduced. This method creates shock hazards on your boat so do it when not aboard.

 

[Duvie]

Water flow across the zinc makes a difference. My zincs only last about 6 months but I am in constant tidal current of about 3 knots.

 

[SteveK]

Remind me again why a stray current travels through the anode via the ground wire back to the originating boat that is leaking AC or DC.

Is it because ABYC says to bond the AC ground to the Bonding system which is bonded to the DC negative, which connects anodes and metal on the water side? Is to protect you from an AC shock off the engine or or metal parts.

 

[GoneFarrell]

Syjos
Thanks, that's the way I learned to hunt for leakage as well. Gonna build a breakout cable, got the parts laying around.

 

[Benthic2]

Is this one of those situations where you should not be swimming in the water because of the risk of electro-shock drowning ?

 

[Iggy]

Clamping around all the wires/shore cord will work. What will happen is in a perfect world with everything on you should read zero. The hot and neutral will cancell each other out.

Or cut into the shore cord and clamp each wire. The difference between hot and neutral would be leakage providing ground measures zero.

But you will need a meter that can read low mA current.

 

[GoneFarrell]

Iggy,
I have a good meter. It sees the mag flux from our planet.
I move it into position then zero it before clamping. Usual noise level 2 or 3 milliamps.

 

[Fletcher500]

Is this one of those situations where you should not be swimming in the water because of the risk of electro-shock drowning ?

When it comes to electrical, always error on the side of caution but I would say no. Quite a few boats out there leak some current back through the ground per my discussions with marina managers and marine electricians. There are hundreds of divers in the ocean every day and I can’t recall a single electrocution. Fresh water risk is likely higher.

New marinas in SoCal are getting the ELCIs with very sensitive ground fault trips.

I am having an electrician install Victron isolation transformers this week. I had them on our previous boat. The lack of a physical connection to the docks electrical system is a good thing. EMI.

 

[backinblue]

Water flow across the zinc makes a difference. My zincs only last about 6 months but I am in constant tidal current of about 3 knots.

I also have zincs that almost disappear in 6 mos. I convinced myself that I had an electrical problem on my boat or that other boats neaby were the problem. I have done numerous checks on my boat and everything is fine. I have found that other boats in the area have the same (problem). My boat is in a river with very fast tidal currrents at times. I now believe that is the root cause and I no longer worry, just replace zincs each season. I personally think that although it's possible, neighboring boats are rarely the cause. Before you convince yourself that your boat or neighboring boats have a problem, check with others nearby and see how long their zincs last. You might be surprised.

 

[Fletcher500]

A lot of variables involved, but My zincs also last about 6 mos.

 

[Ken E.]

The other boats in the marina are depleting your zincs via the ground wire connecting all the boats together.

Installing a galvanic isolator on the ground wire would be one solution.

Installing an isolation transformer would be the best solution. The IT creates it's own ground so it does not use earth for ground, which elliminates other boats ground connection to your zincs.

The transformer, not having a physical connection to the incoming shore AC, alleviates reverse polarity and other AC issues on docks, prevents electrocuting swimmers and allows shore connections to ELCI equipped marinas without tripping the breaker.

My license plate zinc last 10 plus years with minimal wear. I test all underwater metal twice per year using a silver oxide probe and a multimeter.

I am a dealer for Victron isolation transformers.

After I installed an isolation transformer, my anode erosion went to almost zero. In my case, it's a Charles unit.

 

[Iggy]

I also have zincs that almost disappear in 6 mos. I convinced myself that I had an electrical problem on my boat or that other boats neaby were the problem. I have done numerous checks on my boat and everything is fine. I have found that other boats in the area have the same (problem). My boat is in a river with very fast tidal currrents at times. I now believe that is the root cause and I no longer worry, just replace zincs each season. I personally think that although it's possible, neighboring boats are rarely the cause. Before you convince yourself that your boat or neighboring boats have a problem, check with others nearby and see how long their zincs last. You might be surprised.

There could be a wire in the water from the marina that is causing the problem. It is does not need to be another boat.

Most states have passed laws that any new docks with power stations need GFI breakers and each boat must be tested before plugging in. If that boat reads more than 30mA leakage, than that boat can not plug in until fixed. The code is NEC 555.35 which is very interesting read.

 

[Mischief Managed]

My anodes wear pretty quickly, IMO. I added a galvanic isolator, not much difference in wear though.



A twist:



The Interlux VC17M Extra bottom paint that my boat came with is no longer available. It's loaded with copper. After a long discussion with a Pettit paint guy at my local chandlery, I decided to start using Pettit Hydrocoat which is also loaded with copper, AND can go over the VC17. He told me that I should remove all the VC17 in an unbroken circle around every bonded metal part below the water line and paint the bonded parts with Hydrocoat Eco, which has no copper in it. He said to then paint the entire bottom, including the bonded parts, with regular Hydrocoat. The reason for doing this is to break the electrical bond between the copper bottom paint and the boat bonding system. He said the copper in the bottom paint is what was making my anodes wear quickly. I hope he is right... Anyway, something to think about if your anodes wear quickly. For what it's worth, the VC17 always looked cruddiest around all the bonded parts after a season in the water, so maybe the Pettit guy is right.

 

[backinblue]

My anodes wear pretty quickly, IMO. I added a galvanic isolator, not much difference in wear though.



A twist:



The Interlux VC17M Extra bottom paint that my boat came with is no longer available. It's loaded with copper. After a long discussion with a Pettit paint guy at my local chandlery, I decided to start using Pettit Hydrocoat which is also loaded with copper, AND can go over the VC17. He told me that I should remove all the VC17 in an unbroken circle around every bonded metal part below the water line and paint the bonded parts with Hydrocoat Eco, which has no copper in it. He said to then paint the entire bottom, including the bonded parts, with regular Hydrocoat. The reason for doing this is to break the electrical bond between the copper bottom paint and the boat bonding system. He said the copper in the bottom paint is what was making my anodes wear quickly. I hope he is right... Anyway, something to think about if your anodes wear quickly. For what it's worth, the VC17 always looked cruddiest around all the bonded parts after a season in the water, so maybe the Pettit guy is right.

Interesting point. Never heard it explained like that before. I do notice I get a lot more barnacle growth on underwater metals than on the bottom in general. Still trying to make sense of that in relation to the bonding system. For instance, all my thru hulls are bonded. Why would I then want to isolate them from the water or the bottom paint? Would it be the same as removing the bonding wire? I know there are arguments both for and against bonding of thru hulls, but I can't say that I fully understand the reasoning.

 

[syjos]

My anodes wear pretty quickly, IMO. I added a galvanic isolator, not much difference in wear though.



A twist:



The Interlux VC17M Extra bottom paint that my boat came with is no longer available. It's loaded with copper. After a long discussion with a Pettit paint guy at my local chandlery, I decided to start using Pettit Hydrocoat which is also loaded with copper, AND can go over the VC17. He told me that I should remove all the VC17 in an unbroken circle around every bonded metal part below the water line and paint the bonded parts with Hydrocoat Eco, which has no copper in it. He said to then paint the entire bottom, including the bonded parts, with regular Hydrocoat. The reason for doing this is to break the electrical bond between the copper bottom paint and the boat bonding system. He said the copper in the bottom paint is what was making my anodes wear quickly. I hope he is right... Anyway, something to think about if your anodes wear quickly. For what it's worth, the VC17 always looked cruddiest around all the bonded parts after a season in the water, so maybe the Pettit guy is right.

I coat all the underwater metals; thru-hulls, rudder shoe, shaft log and prop with an epoxy barrier coat before the bottom paint goes on,

The epoxy electrically isolates the bottom paint from the metal and the metals from salt water. I don't do that to slow anode wear but rather to prevent the bronze from using the copper in the paint as an anode, dissolving the copper out of the paint. Copper is less noble than bronze and stainless steel.

The epoxy also acts as a primer and allows the bottom paint to adhered to the underwater metal more effectively.

Interlux and Pettit provide detailed instructions on using barrier epoxy for priming underwater metals prior to bottom paint in their painting guides.

 

[syjos]

Interesting point. Never heard it explained like that before. I do notice I get a lot more barnacle growth on underwater metals than on the bottom in general. Still trying to make sense of that in relation to the bonding system. For instance, all my thru hulls are bonded. Why would I then want to isolate them from the water or the bottom paint? Would it be the same as removing the bonding wire? I know there are arguments both for and against bonding of thru hulls, but I can't say that I fully understand the reasoning.

The reason for barnacle growth on underwater metals is that the bronze uses up the copper in the paint in a short time since copper is less noble than bronze or SS.

Read previous post for solution.

 

[backinblue]

Thanks for all the info. That makes sense re. bronze, but I have the same problem with other metals like trim tabs etc. I assume paint made for metals should be fine? Interlux TriLux is what they paint on mine, but they don't do the thru-hull strainers, I think they just paint them with the bottom. I've been spraying them with a zinc paint first but I'm guessing that is not a good insulator, but since it is used on running gear, etc, I thought it couldn't hurt as a base before the bottom paint.

 

[fstbttms]

What do I check next ?

You check your boat. Rapid anode depletion is almost always caused by an issue aboard the boat in question.

 

[backinblue]

You check your boat. Rapid anode depletion is almost always caused by an issue aboard the boat in question.

I have also heard this is true. Many quickly want to believe it's a neighboring boat but rarely is. If in a new marina, is their much difference in the water? Such as more salty, more brackish, etc? Also, if you are now in an area such as a river or channel with strong tidal currents, that could cause more rapid depletion.

 

[fstbttms]

If in a new marina, is their much difference in the water? Such as more salty, more brackish, etc?

What are your anodes made of? Zinc, aluminum or magnesium?

 

[backinblue]

What are your anodes made of? Zinc, aluminum or magnesium?

I assume this is for the OP, but good question! Mine are zinc, may try AL next year.

 

[fstbttms]

I assume this is for the OP, but good question! Mine are zinc, may try AL next year.

No, the question was aimed at you. The reason I ask is that rapid anode depletion may also be cause by using magnesium anodes in salt or brakish water.