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Old 05-03-2017, 11:58 PM   #15
C lectric
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City: Gibsons, B.C., Canada
Vessel Name: Island Pride
Vessel Model: Palmer 32'
Join Date: Oct 2007
Posts: 4,414
When [how long ago] was the zinc installed on the shaft and what was its condition when you dove and scrubbed it? If the zinc was quite solid and very little material flaked off then it is not working.

Anytime a zinc does not show flaking, assuming it has been on and submerged for a while, it is not working and the usual cause is poor preparation of the mounting area, both on the zinc and the protected item, in this case the shaft.

The mounting areas of both must be CLEAN. I sand the zinc mounting area since zinc can oxidize and the oxide can be a poor conductor.

I then always check continuity with an ohmmeter. Several times over the years I have had to dismount a zinc and do more sanding and cleaning.

Shaft zincs almost always have to be rapped with a hammer to get them on tight after tightening the screws, rapping, screws, rapping untill no more slack develops from the raps.

If a yard installs do not assume they know what they are about as I found out one time. Just lucky I was not short of zincs but one of them was just along for the ride. Ever after I check.

Even more important if there is only one shaft zinc.
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