ZINCS

[kjg1951]

What is the difference in the zincs one can buy... there are Zinc Aluminum, Magnesium ??? what is the difference I keep my Albin 28 in brackish water and sometimes go in salt water here in eastern N.C. which should I be using on my trim tabs and rudder and shaft?
Kevin G

[jleonard]

I would use zinc. Magnesium is for fresh water, not sure when you'd use Al.

[joreyn]

Jleonard is correct. Magnesium is for fresh water. Zinc oxidizes in fresh water, eventually rendering them useless.

Aluminum is the best choice (even better than zinc) because it protects you in all water, it lasts longer, does not leach cadmium into the water and it has greater electrical potential (it is more efficient than zinc). The reason why aluminum is not more widely used is twofold. First, it has to be the right alloy. Up until the last 5 years or so, you couldn't always be sure. Second, it used to be expensive.

Today the prices are almost the same - I've seen instances where the aluminum anodes were actually a little cheaper. And they are being offered by really reputable suppliers like Boatzincs.com. Check out their web site. They have some good information.

Also, there was a good article by Steve D'Antonio in Passagemaker on this topic. I wasn't able to access it today, but here's another link.

http://www.passagemaker-digital.com/pas ... pg=21#pg21

[kjg1951]

can you use zinc on the shaft and aluminum on the trim tabs and rudder .... in other words can you mix the two? Or does it all have to be the one kind?

[jleonard]

I mixed the last 2 years. I was boating primarily in fresh water but couldn't find shaft collars in AL so I used zinc there.

[joreyn]

Boatzincs has the aluminum anodes manufactured by Martyr. They give great service. www.boatzincs.com

Performance metals also manufactures them and they are sold throgh West Marine and several others. www.performancemetals.com

Mixing them does not harm your boat as I understand it, but the least noble metal (aluminum) ends up prtecting the more noble metal (zinc) which causes the aluminum to be exhausted prematurely. And, if you are in fresh water for any length of time, the zinc will get an oxidized coating on it, rendering those anodes ineffective

Aluminum would be the perfect choice if you are in both fresh water and salt (or brackish) water. If you are exclusively in fresh water, magnesium is the most effective.

[joreyn]

Here is a good article from the Martyr Metals web site.

http://www.martyranodes.com/sites/defau ... Anodes.pdf