Inboard Outboard Parts

page 127

Alpha Gen II

STERNDRIVE

MerCruiser

Fits MerCruiser Alpha Gen II Drives 1991 & Later

MAGNESIUM

Facts about Aluminum Anodes

Why are aluminum anodes better than zinc anodes in salt water?

Martyr

aluminum alloy anodes are simply more efficient than zinc. Produced

to US Military Specification Mil-A-24779(SH), aluminum anodes achieve a
higher capacity (anode life) while maintaining the same output (level of protec-
tion). In other words, the aluminum anode will protect the same way but for a
longer period of time.

I know aluminum weighs less, why is that an advantage?

This will result in lower freight costs and an easier installation process of the
anodes.

Why can aluminum be used in both salt & brackish waters?

Aluminum has a higher operating potential which allows it to be used in areas
with mixed waters (brackish), typically found at the mouth of a river and inlets.
Whereas zinc is only effective in saltwater, and magnesium in freshwater.

Can you use aluminum anodes on an aluminum outboard/ outdrive?

Absolutely...The important thing to remember is that all genuine Martyr

aluminum anodes are alloys, meaning they are mixtures of many different
metals. The other metals found in aluminum alloy anodes (such as indium
and zinc) work as catalysts to improve the efficiency of the anode. Therefore,
the aluminum anode alloy becomes much more active than the aluminum
outboard/ outdrive thus protecting properly.

Should I worry that aluminum anodes visually corrode differently than zinc
anodes?

This is not a cause for concern. The difference you are seeing is the natural
corrosion effects of two very different metals. It is normal for aluminum anodes
to become rough and pit when corroding while zinc anodes tend to corrode very
smooth and evenly, giving it a sandblasted appearance.

Can I use aluminum and zinc anodes on my outboard/ outdrive?

No! Both aluminum and zinc have different properties. By mixing the two, the
more active alloy will corrode much quicker, and therefore leave your invest-
ment unprotected. It is very important that we communicate this aspect to
everyone, mixing the two anodes will cause harm to their engines.