Basic anode question

EvilZ · **Posted:** Wed Aug 24, 2011 9:56 pm

Is it typical for one of the zincs to deteriorate faster than the other? The gimbal plate zinc on my VP SX has been pretty sacrifical, it seems. The transom plate zinc appears relatively untouched.

Is that normal, or should I be looking for bad contact? I suppose I should have done a continuity test before pulling it off....

230 Mike · **Posted:** Wed Aug 24, 2011 10:05 pm

How old are they? My first thought is that the one that hasn't worn as much might have a contact problem. Also, are you certain they're of the same material?

EvilZ · **Posted:** Wed Aug 24, 2011 10:18 pm

I don't recall ever changing them, so they would be '02s...
The transom plate is zinc - I can still read the part number. The gimbal plate is beyond identification.

Paul I. · **Posted:** Wed Aug 24, 2011 10:29 pm

Every year I change mine. Rule of thumb, don't let the get under 50% worn/deteriorated. If you do, you run the risk of damaging the drive.

I take it you boat in salt water? If so, than you should use ether zinc or aluminum. The manual should tell you which one to use.

230 Mike · **Posted:** Wed Aug 24, 2011 10:34 pm

I don't think uneven wear necessarily indicates a problem, but if they're worlds apart I'd replace them both and check continuity. Also, if it took 9 years to wear down, that might be another indication of a continuity problem. That's quite awhile. I'll probably replace mine next year, and I don't even use my boat.

For salt, use zinc.

EvilZ · **Posted:** Wed Aug 24, 2011 10:39 pm

Yup, I boat in salt much more often than fresh, so zincs for me. But, I don't dock my boat and hook up to shore power, so I think my anodes would last considerably longer than those that do.

I agree that replacing both and getting a fresh start is cheap insurance in this case.

Paul I. · **Posted:** Wed Aug 24, 2011 11:10 pm

Just because your in salt water does not mean you use zinc only. Your drive "might" be made for aluminum anodes.

230 Mike · **Posted:** Thu Aug 25, 2011 12:57 am

However, the 2002 VP SX and DP/SM did specify zinc for salt, magnesium for fresh, and aluminum for brackish. Many were shipped with aluminum since the plant doesn't know where the boat will be used, but for most people that isn't the best choice.

EvilZ · **Posted:** Thu Aug 25, 2011 4:21 pm

An interesting message I received from a supplier:

"Zinc can be used in saltwater; magnesium can be used in freshwater (never in salt or brackish water); but the most widely effective anodes these days are being made of aluminum, which can last up to 50% longer, and remain active
anywhere — in fresh, brackish and saltwater. How, you may ask, does an aluminum anode protect an aluminum outdrive? The answer is that an anode is made with an aluminum alloy that is significantly different (more anodic) than the alloy used
on an outdrive.

A word of warning: Don’t mix anodes! If you decide to use aluminum anodes, then use only aluminum anodes throughout the boat. When two different anodes are used, one (the least noble) will protect the other, which then won’t do it’s job."

So, since I boat in both salt and fresh, it would seem that aluminum might be the better option after all?

230 Mike · **Posted:** Thu Aug 25, 2011 4:38 pm

If you're in salt 90% of the time I'd go with zinc. But if it's more like half & half, then yes - go with aluminum but keep a close watch on everything and do occasional continuity checks.

Graham R · **Posted:** Thu Aug 25, 2011 4:58 pm

I boat in saltwater, my boat has the VP ACP system fitted (std on the GXi), Zinc Anodes last quite a few seasons I don't believe Al anodes are available for the SX-MHP transom shield.

A word of warning; both the retrofit ACP on my 1999 boat and the std ACP on my 2004 boat suffered from electrode failure. The potting compond VP used is very brittle, biscuit like in consistency (= cheap), water got in and corrosion of the copper cable cracked it, leading to more water ingress and corrosion up the cable. Unbelievable it was not tinned cable ! Anyhow, I traced it back to clean copper, crimped on new cable, made a new crimp between the electrode and the new cable and encapulated the lot, the joints first with epoxy and then the lot with a PU sealant/ adhesive; should last forever !

Graham

ric · **Posted:** Fri Aug 26, 2011 9:44 am

where can I get magnesium for my 2000 h180 volvo?

Cap'n Morgan · **Posted:** Fri Aug 26, 2011 10:32 am

ric wrote:

where can I get magnesium for my 2000 h180 volvo?

http://www.boatzincs.com/?gclid=CILSztG ... 5god8jBmPg

West Marine 7478 S Orange Blossom Trl # A, Orlando - (407) 857-7337

ric · **Posted:** Fri Aug 26, 2011 10:44 am

Cap'n Morgan wrote:

ric wrote:

where can I get magnesium for my 2000 h180 volvo?

http://www.boatzincs.com/?gclid=CILSztG ... 5god8jBmPg

West Marine 7478 S Orange Blossom Trl # A, Orlando - (407) 857-7337

awesome. I need these, I noticed some corrosion starting appear on the outdrive

www.iFourWinns.com

Basic anode question

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