is there a relationship between grounding and zinc consumption

I installed stabilizers and it took some time to complete. I plumbed the heat exchanger along with hydraulics first around February then the wiring for controls. i didnt get the bonding wire connected until a couple weeks ago . The heat ex changer is isolated and only connected by the hoses. I checked the zinc in the exchanger last week and it was shot.The engine zincs show normal wear.Is it possible that not having the bonding wire connected that it caused increased wear on the one zinc? I normally change every 6 months and they are about 50 percent.

magna 6882 said:

I installed stabilizers and it took some time to complete. I plumbed the heat exchanger along with hydraulics first around February then the wiring for controls. i didnt get the bonding wire connected until a couple weeks ago . The heat ex changer is isolated and only connected by the hoses. I checked the zinc in the exchanger last week and it was shot.The engine zincs show normal wear.Is it possible that not having the bonding wire connected that it caused increased wear on the one zinc? I normally change every 6 months and they are about 50 percent.

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Yes, they can be related.


No mounting brackets that could be electrically connecting the cooler to something else?


I've never checked this, but wonder if the hydraulic hoses could be conductive? The hoses are typically wire reinforced, and if the hose end crimps through to the wire.... Might be worth checking...


If fully electrically isolated, then the zincs in the cooler are only protecting the cooler, and doing their job.


For what it's worth, on my last two boats the hydraulic cooler zincs have always gone faster than others.


You could try bonding the cooler, and see if the zincs last appreciably longer.

What size anode and aluminum or zinc?

My transmission cooler always gets eaten first. While it's bonded to the engine and large transom anode plate, it still goes first.

Ted

I did just ground the cooler but just a couple weeks ago. I cant say if the original was zinc or aluminum. It looked like zinc. It is the smaller size pencil zinc and i did replace with a zinc. It is a bronze cooler and i used stainless fittings for the hoses.

If you're in salt water, zinc is what you want to use if the rest of the anodes are also zinc. Don't know the length of the original anode or what you replaced it with, but I tend to buy them as long as possible and cut to fit. In a perfect world, I want the space between the end of the anode and the cooler wall opposite the anode hole to have about a 1/2" gap.

Ted

As another data point, on my last boat the keel cooler also went through zincs faster than everything else, and they were much more of a pain to replace because they required a dive on the boat. I experimented with bonding and not bonding the keel cooler and it made no detectable difference.

I guess i made an assumption that the bonding running throughout the boat had something to do with corrosion since it is was installed so purposeful. All thru hulls and metal components are bonded very consistently .

magna 6882 said:

I guess i made an assumption that the bonding running throughout the boat had something to do with corrosion since it is was installed so purposeful. All thru hulls and metal components are bonded very consistently .

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It does, primarily by connecting metal parts that don't have zincs to parts that do have zincs.

For one simple reason, there is no relationship between bonding a heat exchanger and anode consumption, the heat exchanger and the rest of the vessels anodes, those on the hull, are in two different bodies of water, and thus there is no ion path, and as such those other anodes offer the heat exchanger no additional protection. Bonding or not bonding the heat exchanger should have no effect on HE anode life.

Bonding of underwater metals does, or can, offer them protection from galvanic and stray current corrosion, however, in the case of galvanic corrosion the protected metals and the anode are immersed in the same body of water.

For seawater, you can use either zinc or aluminum anodes with good effect.

There's no harm in bonding the HE, it might, in some rare cases, protect it from stray current, if the outside of it got immersed in bilge water.

More on bonding systems here https://stevedmarineconsulting.com/wp-content/uploads/2014/03/BondingSystems138_05.pdf

Anode selection https://stevedmarineconsulting.com/galvanic-isolators-and-zinc-anode-selection/

Lying Herring Bay, Elovoi Isle, AK