Seems I may have a " sacraficial " out drive... ANODES ???????

[Chris288]

boats an 05, put 60 hours on last year and 30 so far this year. I leave the boat in the water for about 3 weeks at a time between pullings and cleanings. Last year the anodes were barely touched and I figured since I did not have shore power and everything looked fine I was o.k.. This year, anodes are still in new condition and I noticed some paint bubbling around the edges of the drive in the beginning of season, I was thinking I got a bad paint job from merc. seems to have gotten a bit worse and was starting to worry about it,,, finally after about a 120 mile trip down to the city for the SBI race the drive seems to have a lot of damage.. I guess the paint was hiding the damage and the long trip pulled alot of the paint off and now I have what seems to be major pitting... On the lower part of the drive a pitted gouge seems to have appeared out of nowhere,, and appears to be pretty deep.

The boat is used in the upper Hudson and is for the most part fresh water. when I drove out to the Sunsation factory I asked which anodes they used and said they use the ones that come standard from merc. I figured Michigan, fresh water, Hudson mostly fresh water, I had the correct anodes,, appears this is not the case,, my drive seems to have deteriorated very badly and i'm pretty upset about it.. Any suggestions... does the 496 HO have the mercathode system like previous engines ??, do I have the wrong Zincs ?? can I sandblast the drive down and have it re-painted or should the lower case be replaced... Thanks Chris


P.S. I talked to the wife last night, she had a boat when we met that she left it in the water for 6-7 months at a time and her anodes were gone after each season in the Hudson approx. 15 miles south of where we keep ours now, this sucks as I should have KNOWN BETTER when the anodes were still intact after last season...

[Rippem]

MAGNESIUM ANODES...NOT the zinc they come with...

the one behind the prop is IMPORTANT

you got bad info from manufacturer about "the ones they come with" Zinc only in pure salt or heavy brackish!

and you can add more mag anode for more protection. I added these this year, in addition to running magnesium in all other locations from the start. See pic. The addition of these on both sides of my caps STOPPED the damage to the caps. These were heavily eaten in 8 weeks in the water...doing their job! They are side mount outboard anodes by Canada Metal. $7 apiece.

I have massive amount of stainless (wing plates ect) creating even more of a problem, leave my boat slipped for 3-4 months in a boathouse with shorepower on and/or all around me, and after 2 seasons have very little damage. The bottom (raw) edge of the top cap, and the diameter of the lower behing the prop are the only spots and it's minor. It's the proximity of the S/S (prop, wing plates) to the aluminum case and the immediate proximity "battery effect" (electrolosis).

All the mess is from the muffler project I was doing at the same time.

[Rippem]

test your MerCathode to make sure it's hooked up and/or the controller isn't bad. Search thread about testing the system.

[Chris288]

Rippem,, thanks for the great info,,, I knew better and even questioned Sunsation about the Anodes on the drive,,, even had a post about this BEFORE we even brought the boat home...

How can I be sure which Anodes I have ?? Like I said, Sunsation told me they just use the ones that come with the drive. If most of Sunsatons boats are sold for fresh water use, then is it true that they pretty much ALL have the wrong Anodes from the factory ??????????????????????????????.

[Rippem]

Yup, Merc ships 'em with ZINC anodes.

Magnesium anode kits are available from boatfix.com

The west part # for the additional ones I put on is #1258623
Canada Metal # CM123009M
$6.99 each

drill the threaded hole in the anode out big enough to get an 8 or 10-32 cap srew thru
drill and tap the cap according to my pics

I used S/S allen head cap screw and a S/S lock washer, and put a little pipe dope on the threads...even tho that area of the cap is a void.

NO issues whatsoever

I posted the whole top cap mounted anode project, and the reasoning behind Magnesium in fresh water, in tech in May/June and no one seemed to care!

[Rippem]

If most of their boats are sold for fresh water use, then is it true that they pretty much ALL have the wrong Anodes from the factory ??????????????????????????????.

drives are being eaten by the thousands for those who are unaware!

[Chris288]

I see they also have aluminum anodes,,, why would you use alum. anodes to protect an alum. drive ???? Says they are for salt, brackish or fresh....

[Rippem]

magnesium is less noble (sacrifices easier) than aluminum I believe.

I KNOW that both are substantially less noble than zinc.

mag or alum anodes in salt water would be gone in a week (or two) because the specific gravity of SW enhances the electrolytic process.

magnesium is the right choice for you.

keep thinking "battery" and what any of us remember of high school or college chemistry...and you'll develop a better picture in your mind of what is happening between two dissimilar metals submerged in water of varying specific gravity.

[Chris288]

Fired off a letter to Merc. waiting for a response...

[Chris288]

UPDATE !! Merc. already called back... WOW,, talk about quick response,,, seems all their drives come from the factory with Aluminum anodes which they say works for salt, fresh, and brackish.. looks like I may have another problem, rep said to contact a dealer and have a hull potential test done and then to call merc. with the numbers,,, he also said there is a 3 year corrosion warranty,,, I'm looking for a dealer as we speak... maybe there's hope...