aluminum/zinc anodes

[horsemel]

I have read the discussions on the need to use aluminum shaft and engine anodes in fresh water.  I also understand you should not mix the types of anodes on the boat.  Great discussion.  How do you tell if you have zinc or aluminum anodes?  Both are silver.  I was going to change my engine anode this weekend, but now don't know what to do since she is in the water and I have no clue what is on the shaft. I have engine anodes in the parts supply from the PO but they aren't labeled as to material. I'm thinking I should just replace the engine anode with what I have and worry about changing both when she comes out of the water this fall.
Mark Mueller

[Ron Hill]

Mark : I'm not too sure that I'd be that choosy about whether your anodes are Al or Zn - believe that I'd stick with the Zn as they are more plentiful and cheaper. 

Both are a silvery color, but Zn is much heavier than Al. 

[Rick Johnson]

Mark, I think the following link might answer your question.

http://gulffishing.com/tips_anode.html

Cheers,

Rick

[horsemel]

Rick, Great article and explains things simply.  Think I will just use the zinc I have for the engine this year and switch to aluminum next year.
Thanks
Mark