how often do you change your zink anodes

[ol tuna skipper]

I have a 19 foot alumaweld and was wodering how often I should change my zink anodes.

They have slight pitting and I see salt water mabey 5 days a year. Mostly fresh water usage in the Columbia and M.-Channel

[Master Baiter]

Ol Tuna,

When I bought my motor I was told that the only purpose for the anode was if you planned on leaving the motor berthed in salt water. Otherwise it was useless. Can anyone clarify this?

Thomas

[Pilar]

Even in fresh water, zincs protect your expensive metal boat parts. The idea is to let the cheap (relatively cheap) sacrificial anode take the galvanic corrosion instead of the expensive motor or hull. On an outdrive or outboard the zinc steering fin should get changed at about 1/3 depletion. It just wont steer so good after that. If you have a closed cooling system, change the pencil zinc in the heat exchanger at 50% depletion. The zinc blocks on other boats should go at 50% too. Having said that if a large, moored boat is hauled out for repairs or bottom paint, change the zincs too.

Never paint a zinc anode, it wont work anymore!

All it takes to get galvanic corrosion is dissimilar metals in an electrolyte. On any outboard that is the prop shaft (Stainless steel) and the prop and housing (aluminum alloy). Salt water is great for an electrolyte but fresh water has conductivity too. If you moor your boat bad things can happen at the dock. Sometimes an electrical charge can occur at the dock from faulty equipment on a neighbors boat or electrical service problems at the dock. Check your zincs often as you can, they are all the protection you have.

Once they become dull and pitted they are less effective. The bottom line is they are a hell of a lot less expensive than a motor or hull skin.

[Jennie@ifish]

About as often as I pumice my heels.
Jen

[Hookset]

You should also brush the oxidation off your zincs. Every other trip only takes a sec and when they look dull. I usually do the boat with a brush and a little sand paper on the smaller ones.

hook

[Deleted User]

Hey, that's kind of personal don't ya think Ol Tuna? images/icons/grin.gif