Which anode type to use? Mg Al Zn

PitchFork · Sep 30, 2010

I have a Alpha One Gen 1 with SS Prop trailered only used in freshwater 120 hours a season.

I recently purchased an aluminium anode kit and wanted to make sure this is ok to use or should I look for an Magnesium Kit?

Kit has Trim Tab, trim ram rod, Gimbal Housing, and transom bolt anodes.

I'm not sure what anode type is on it now it has been on their since I bought the boat 3 years ago.

Thanks,
PF

Bifflefan · Sep 30, 2010

Re: Which anode type to use? Mg Al Zn

After reading this link, I guess I dont know anything about them. But I do know a bit more now.

PitchFork · Sep 30, 2010

Re: Which anode type to use? Mg Al Zn

bifflefan said:
After reading this link, I guess I dont know anything about them. But I do know a bit more now.

Thanks I guess Aluminium is the winner I will be installing ithe kit with my new SE106 drive tomorrow.

Bluestream · Oct 2, 2010

Re: Which anode type to use? Mg Al Zn

Since the gear case in Aluminium, whats the point of an aluminium anode? I would use the zinc as they came with the drive when new...

Dshow · Oct 2, 2010

Re: Which anode type to use? Mg Al Zn

When would magnesium be used? I've heard magnesium is used for freshwater, why not that?

According to the Merc site:
All MerCruiser sterndrives come standard with aluminum sacrificial anodes & 3-year warranty against certain types of corrosion (see your owner's manual for more details). Seacore models receive a four-year limited corrosion warranty.

http://www.mercurymarine.com/servic...intenance/faqs/mercruiser/?category=corrosion

Bifflefan · Oct 2, 2010

Re: Which anode type to use? Mg Al Zn

Bluestream said:
Since the gear case in Aluminium, whats the point of an aluminium anode? I would use the zinc as they came with the drive when new...

Read the link I posted.

Dshow said:
When would magnesium be used? I've heard magnesium is used for freshwater, why not that?

Yes it is. Also read the link.

sethjon · Oct 2, 2010

Re: Which anode type to use? Mg Al Zn

PitchFork said:
I have a Alpha One Gen 1 with SS Prop trailered only used in freshwater 120 hours a season.

I recently purchased an aluminium anode kit and wanted to make sure this is ok to use or should I look for an Magnesium Kit?

Kit has Trim Tab, trim ram rod, Gimbal Housing, and transom bolt anodes.

I'm not sure what anode type is on it now it has been on their since I bought the boat 3 years ago.

Thanks,
PF

If you stay fresh water use mag. Zinc is good for either.

Don S · Oct 2, 2010

Re: Which anode type to use? Mg Al Zn

Bluestream said:
Since the gear case in Aluminium, whats the point of an aluminium anode? I would use the zinc as they came with the drive when new...

Completely different types of aluminum alloy. Merc stopped using zinc many years ago, because it didn't work very well. Here is one of the service bulletins from 91 on the change from zinc to aluminum anodes.
http://www.boatfix.com/merc/Bullet/91/91_19.pdf

Magnesium anodes are for freshwater only, not to be used in saltwater, aluminum can be used in either fresh or salt.
For a trailered boat magnesium or aluminum will work because the boat is not sitting at a dock where the anodes are needed most.

sethjon · Oct 2, 2010

Re: Which anode type to use? Mg Al Zn

Bluestream said:
Since the gear case in Aluminium, whats the point of an aluminium anode? I would use the zinc as they came with the drive when new...

But magnesium is better in fresh water which is not good for salt.

SteveRay · Oct 2, 2010

Re: Which anode type to use? Mg Al Zn

Check out boatzincs.com.......Awesome people and great service.

I can tell you that I learned the hard way this year....I have an Alpha Gen II
with stainless prop and left original anodes in great shape on and suffered corrosion as a result of the stainless prop.

Bluestream · Oct 3, 2010

Re: Which anode type to use? Mg Al Zn

Don S said:
Completely different types of aluminum alloy. Merc stopped using zinc many years ago, because it didn't work very well.
.

I wonder why it took 20 years to figure this out?

On my 22 year old boat the zinc seems to have worked very well. No corrosion on the aluminium, and the 3 zinc anodes are about 50% gone.

Which anode type to use? Mg Al Zn

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