Zinc changing season is coming

Dan Johnson · Feb 25, 2013

Charles, some answers...

1. Yes, I use a very fine sandpaper strip to clean the shaft where the zincs are applied ( I use two) so that good contact is obtained. Once they're snugged up, I hold a hammer against one side and lightly tap the other to ensure that they have seated firmly. I've broken one of the set screws trying to do it with just torque.

2. No, I haven't found an anti-seize compound to be necessary. Backing the set screws out a ways and using a thin screwdriver blade starts the separation and removal process. The longest I've gone is two years between changes due to minimal erosion of the zincs.

3. No, I don't use a sealant of any kind.

About the only way I can think of to determine the efficiency of the contact between the zinc and the shaft is with an ohm meter. Hard to do underwater.

fstbttms · Feb 25, 2013

There's a season for changing zincs?

fstbttms · Feb 25, 2013

Charles Erwin said:
Yes there is -- but the season only effects those who put the boats on the ground for the winter, and now must remove themselves from the yard before the spring rush.

Charles

Didn't know people hauled for the winter in the PNW.

Don S/V ILLusion · Feb 25, 2013

It's good to learn new things

Maine Sail · Feb 25, 2013

Charles Erwin said:
1. Do we clean/polish the shaft (or the shaft nut ) where we intend to fasten the new zinc?

Yes the shaft should be perfectly clean. You also clean the inside surfaces of the zincs. Zincs will oxidize rapidly so I wet sand them or use burgundy Stotch-Brite immediately before installation. Once installed & snugged a light TAP with a hammer will seat them then re-snug the nuts tightening evenly.

Charles Erwin said:
2. Do we use anti-seize compound between the zinc and the shaft (or shaft nut) mounting surfaces? If so, aluminum, copper, or nickle anti-seize compound?

No.. If you want to put a little Tef-Gel on the clamping bolts for a shaft zinc to prevent thread galling that is fine but nothing between the two metals. Most "antizeize" products will throw another metal into the mix which you don't want or they are "dielectric" which defeats the entire purpose of the connections....

Charles Erwin said:
3. Do we apply any sealant so as to prevent water entering the surface between the shaft and the zinc. If so what type?

No..

Charles Erwin said:
When the boat is in the water how does our diver make sure there is excellent contact between the new zinc and the to-be-protected protected shaft/propeller?

Charles

You check it with an silver / silver chloride reference cell...

Oh and the ONLY zincs worth spending money on are the Godfrey zincs.... They have a full ring inside that maintains electrical contact. The ball bearings and no bearing style are pretty poor in comparison.. Godfrey zincs are also made right here in the good old USA, not China....

This is a Godfrey Zinc:

fstbttms · Feb 25, 2013

Maine Sail said:
Oh and the ONLY zincs worth spending money on are the Godfrey zincs...

I'd respect them more if the definition they have for "electrolytic corrosion" on the home page of their web site wasn't the definition for galvanic corrosion...

fstbttms · Feb 25, 2013

Maine Sail said:
Oh and the ONLY zincs worth spending money on are the Godfrey zincs...

My jaw just about hit the floor when I looked at their prices. $41 for a 1" shaft zinc?

I'm sorry, but that is outrageous. The Godfrey zincs will need to be replaced just as often as any other quality anode, yet they cost three or four times as much.

Maine Sail · Feb 25, 2013

fstbttms said:
My jaw just about hit the floor when I looked at their prices. $41 for a 1" shaft zinc?

I'm sorry, but that is outrageous. The Godfrey zincs will need to be replaced just as often as any other quality anode, yet they cost three or four times as much.

That is a "list price" get them from a Godfrey dealer and they a much less money.

fstbttms · Feb 25, 2013

Maine Sail said:
That is a "list price" get them from Godfrey dealer and they a much less money.

Unless they can be had for around $10 or $11 (and 50% off that wholesale), I can't see the value. A properly installed zinc of any quality brand is going to protect the intended part and isn't going to come off prematurely.

Maine Sail · Feb 25, 2013

fstbttms said:
I'd respect them more if the definition they have for "electrolytic corrosion" on the home page of their web site wasn't the definition for galvanic corrosion...

Yep LOTS of people, web sites and even books mess up these definitions. The one that drive me insane is "electrolysis". Electrolysis is what fat hirsute lady's have done to their upper lip

or is the changes to an "electrolyte" but it is frequently misused, even by pros and authors....

fstbttms · Feb 25, 2013

Maine Sail said:
The one that drive me insane is "electrolysis".

Agree 100%.

Maine Sail · Feb 25, 2013

fstbttms said:
Unless they can be had for around $10 or $11 (and 50% off that wholesale), I can't see the value. A properly installed zinc of any quality brand is going to protect the intended part and isn't going to come off prematurely.

The Godfrey's do last longer because they don't tend to wear away as unevenly. With Camp & Martyr I can sometimes measure no protection even with an "intact" zinc. Never seen that with a Godfrey even when there is just a small amount of zinc left.. Expensive, yes but so are the props and stuff we are protecting. Still, all I all, a cheap boat expenditure.

fstbttms · Feb 25, 2013

Charles Erwin said:
Would the answers be different for "end of shaft zincs" like this one?

Well, you've got a point there. Can't say that every prop zinc I've installed has stayed on as long as I'd like. Unfortunately, there really isn't an alternative (and Godfrey does not make them.) I increase my success rate by replacing the allen screw with a hex-head bolt and two lock washers. That way, I can get a wrench on the bolt head and really torque it all the way down.

fstbttms · Feb 25, 2013

Maine Sail said:
With Camp & Martyr I can sometimes measure no protection even with an "intact" zinc.

I never use Camp or Martyr anodes. Both brands are inferior, IMHO. Reliance and Sea Shield are high-quality however, and recommended by this hull cleaner.

I'm assuming your CS 36 has a 1" shaft. What do you pay for your Godfrey zincs?

fstbttms · Feb 25, 2013

Charles Erwin said:
In either case - whether shaft or tail nut - the three usual anti seize compounds are conductors not insulators. For example - how could zinc anti-seize introduce a different metal into the mix? And so why not use zinc anti-seize between the nut and the zinc to assure a reasonably good electrical bond.

I'm not sure why you would anti-sieze in the first place. You don't want the screws to come off easily.

Zinc changing season is coming

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