Sacrificial anodes

[Off Course]

I do most of my boating on the Great Lakes (Fresh Water), I have a Mercruiser Bravo III w/Stainless Props, I have read that Magnesium is better than Zinc for fresh water boating.

My Question: Is there a way you can tell the difference by looking at them, I want to know if I have the right Metal.

Thanks,
Off Course:huh:

 

[Redhook98]

YES! You must have magnesium. Especially with the Bravo-3's. Magnesium should be the predominant sacrificial material in your area. But obviously ask before you buy. Most packaging will clearly state Aluminum, Zinv or Magnesium. (hint, zinc is the heaviest. Aluminum and magnesium are pretty light metals).

In saying all this though, if you do put magnesium on your boat, do NOT put it is salt water or heavy brackish water. The magnesium is to active and damage could occur. To much protection is not always a good thing.

 

[Presentation]

...My Question: Is there a way you can tell the difference by looking at them.....

I'm going with No


PS: Consider adding this Bravo III Propeller Nut with Magnesium Anode

http://www.boatzincs.com/mercruiser-magnesium.html


If you are holding identical new anodes in your hand and one is zinc and one is magnesium the one that is lighter is magnesium.

I know of no way to tell if the anode is zinc or magnesium simply by looking at it.

 

[jason78]

I'm going with No


PS: Consider adding this Bravo III Propeller Nut with Magnesium Anode

http://www.boatzincs.com/mercruiser-magnesium.html


If you are holding identical new anodes in your hand and one is zinc and one is magnesium the one that is lighter is magnesium.

I know of no way to tell if the anode is zinc or magnesium simply by looking at it.

I just ordered this prop anode kit today. It is a heck of a deal compared to what Mercury wants for the pre-2004 B3 Prop anode kit!!!!

 

[Stray Cat]

My Question: Is there a way you can tell the difference by looking at them, I want to know if I have the right Metal.

Ditto on the No. I have about 50% left after one season, so I replace the magnesium annodes every year for both B3's, my drives still look new after 3 seasons.

 

[Off Course]

Thanks for the input!:smt038

But let me get this straight, would you just put the anode on the prop nut, (mine does not have one now because you can plainly see the nut), and not change the other 3 anodes, not knowing what metal (zinc or magnesium) they are.

Off Course.....P.S. By the way I did not name the boat, Off Course is what the previous owner hand painted on the transom and I did not think it was worth that much work just to end up pissing off the God's.:huh:

 

[Stray Cat]

But let me get this straight, would you just put the anode on the prop nut, (mine does not have one now because you can plainly see the nut), and not change the other 3 anodes, not knowing what metal (zinc or magnesium) they are.

Replace all of them with a magnesium annode kit for the year of your drive, AND install the prop nut annode kit. Depending on the mfg. date of your drive, it may have two annodes on the cavitation plate (right above each prop) since your's doesn't have the prop annode, my guess is that it doesn't.

Many members here a very satisfied with www.boatzincs.com Don't let the name fool you, they have magnesium annodes too.

Don't let Neptune make you skitish about changing your boat name....he can be bought!

 

[jason78]

Thanks for the input!:smt038

But let me get this straight, would you just put the anode on the prop nut, (mine does not have one now because you can plainly see the nut), and not change the other 3 anodes, not knowing what metal (zinc or magnesium) they are.

Personally, I would say if you don't know what the others are made of, then replace them all with known magnesium anodes. I say this because from what I have read, magnesium is the most active and by theroy, if you just put a magnesium prop anode on, it could take all of the majority of the corrosion on it's own if your other anodes are not magnesium. If all anodes are magnesium they should share in "taking the hit". Everything I have read has said the most active metal in the vacinity will bear the corrosion. I also have a pre 2004 Bravo 3 that was not factory equipped with the prop anode. Our outdrives also only have one anode above the prop where the post-2004 drives had 2.

 

[springer3]

Magnesium is quite a bit harder than zinc. Try scratching the surface with a nail file or knife. The softer material is zinc (in case they are attached and you can't pick them up to test the mass).