Zincs

Every marina or environment will be different. Squalicum in Bellingham is a "hot" marina and the average service life of the typical "license plate" zinc is about six to eight months. The marina often has a layer of fresh water on top due to nearby streams and the river that empties into the bay. So many boaters including us hang a zinc on a heavy cable down about six or eight feet off the boat. The other end of the cable is attached to the boat's bonding system.

We and the boaters I know (and boats I see hauled out) never have any slime or algae on the zincs. I was told by people in the business ess that this is because the tiny current in the anode prevents growth from occuring. If there is slime or growth on an anode, it means the anode is not doing a very good job for some reason.

People have tried aluminum anodes in our marina and in every case I have been aware of they soon went back to zinc as they found the aluminum was not providing as effective a level of protection as the zinc does. But this probably varies wiith the environment the boat Is in.

Marin said:

Every marina or environment will be different. Squalicum in Bellingham is a "hot" marina and the average service life of the typical "license plate" zinc is about six to eight months. The marina often has a layer of fresh water on top due to nearby streams and the river that empties into the bay. So many boaters including us hang a zinc on a heavy cable down about six or eight feet off the boat. The other end of the cable is attached to the boat's bonding system.

We and the boaters I know (and boats I see hauled out) never have any slime or algae on the zincs. I was told by people in the business ess that this is because the tiny current in the anode prevents growth from occuring. If there is slime or growth on an anode, it means the anode is not doing a very good job for some reason.

People have tried aluminum anodes in our marina and in every case I have been aware of they soon went back to zinc as they found the aluminum was not providing as effective a level of protection as the zinc does. But this probably varies wiith the environment the boat Is in.

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Marin

See bold areas in your quote above. Reason you get no coating on your zinc is due to your "hot" marina area and being primarily in salt water. Your zinc's surface is disintegrating ("flaking off") so quickly, (in its correctly functioning less noble anode mode) that coatings get no chance to form. Where as in our "not hot" fresh water docking area the zinc surface stays on so much longer that surface coating can form. I've never seen surface coating form on zinc in water that is fully or majority salt due to its considerably increased electric conductivity as compared to pure fresh water. I'm glad to hear zinc keeps your boat's cathode metals free from electric current ruin!

Cheers, Art

If you had a galvanic table it would be clearer. Metal mfg companies for centuries have used the galvanic table. The lower rate metal will protect the high rated metals, and the larger the spread the better the protection. Sure their might be an aluminum magnesium that has a little lower galvanic rating then zinc, but on the table magnesium is the lowest.

If the zincs are lasting to long then magnesium, which has the lowest galvanic rating should be used. If the zincs where not lasting long enough there are two choices. 1) added a additional/bigger zinc and/or 2) change to aluminum with a HIGHER galvanic rating which would still protect the metal with higher galvanic rating. When we moved to Everett, brackish, the bow thrust zincs where not lasting, so I hung a grouper zinc over the side which help prolong the thruster zincs and additional protection. When we pulled I had a big diver dream, license plate size, installed for the bow thruster.


Lastly if you are still unsure, then ask the boats around you what they use and how long they are lasting.

rwidman said:

Only if they are still protecting your underwater metal.

I don't know how we figure that out, but I don't want to save money on anodes only to see my prop eaten away.

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I am in complete agreement with you.....

It will cost me far far less to buy zincs than to buy two new nibral props....

I should ask my diver if he knows anything about these new navalloy zincs.

JAT said:

I am in complete agreement with you.....

It will cost me far far less to buy zincs than to buy two new nibral props....

I should ask my diver if he knows anything about these new navalloy zincs.

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I'll ask mine also but not until I've used up what I have.

I'm sure he's putting on zinc when he replaces them so if I were to change to aluminum, I would have to make sure he used aluminum, not zinc when he replaced them.

I would check the pencil zinc lenght before installing. I have to cut off 3/4 inch on my Lehman 135 SP to prevent binding at the center of the heat exchanger end cap. Same on my genset.

jackgarnier said:

I would check the pencil zinc lenght before installing. I have to cut off 3/4 inch on my Lehman 135 SP to prevent binding at the center of the heat exchanger end cap. Same on my genset.

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Ditto.... I have to custom cut the zincs that fit in my stainless MESA wet manifolds!! Small chore...but a full length one won't fit.

Hmmmmm, maybe I should see if I can find shorter ones to use....

JAT said:

Hmmmmm, maybe I should see if I can find shorter ones to use....

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I was going to suggest that.:lol:

You shouldn't have to cut zincs for the Lehman 135. There are shorter ones.

SeaHorse II said:

I was going to suggest that.:lol:

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In truth...I have been using up the supply of the extras that the PO left with the boat when we boat her..... I'm getting to the end of that supply.....

fstbttms said:

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As someone who sees a lot of boat bottoms, do you agree with this?

rwidman said:

As someone who sees a lot of boat bottoms, do you agree with this?

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100%. Wouldn't have posted it otherwise.

fstbttms said:

100%. Wouldn't have posted it otherwise.

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Thanks.