Shaft Zinc Size

[Ron Vanderveer]

I am having some trouble keeping a shaft zinc on the shaft of our Hunter 27 (1982 Cherubini model). I believe that rather than a huge electrical conductivity problem at the marina, the zinc may be just falling off of the shaft. Here are my reasons for thinking that:1) I have replaced the thing three times, and each time when I go underwater to check for the replaced zinc (after a few weeks) there is no zinc, nothing, not even a leftover hunk of anything. 2) When I install that zinc on the shaft, I don't get a snug fit. I am using a 1" diameter zinc from the Canadian company called Martyr. But that zinc actually seems to be a bit small on the shaft, 'cause I don't get the two halves to fit together snugly: there is a small gap on either side where the two halves of the zinc screw together, but don't actually meet each other. They do make good contact with the shaft, though. So I wonder if that lousy fit is causing a vibration problem which causes that zinc to unscrew itself and fall off. I tried a 1 1/8 size and it was way too big, just flopped around on the shaft.So, here are the questions: Do I have some sort of weird shaft size that needs a special zinc? I cleaned the shaft very well before this last install (and the water is getting a little cold, even down here in Florida!) so I know that it isn't growth or something. And the shaft appears to be brass, just for informational help.Or, do I have some wild electolysis at the dock and I am truly losing a zinc every two months? I guess I could experiment with one of those fish-shaped zincs over the side while docked? The possiblity of a bad electrical leak somewhere is clear to me, but then again, I don't normally have the shore power plugged into the boat at the slip. I guess it could be someone elses boat?Any help would be appreciated. Ron VanderveerMelbourne, Florida

 

[tom cooper]

zincs

I find that as well as tightening the zinc you should take a hammer and hit the zinc,while supporting the other side with a block of wood,Do this twice you will get the screws to close much tighter.Also look for the new design zinc from this company. good luck

 

[Tim McCarty]

Zincs...always a pain

they never seem to fit quite right, so, you need to do "modifications" although the zincs I've purchased at West Marine seem to fit fine. That was with regard to my old, '82 h27. No one wants to believe me...I probably sound like a broken record by now), but, with my 29.5...I have no room whatsoever on the shaft due to the way it is fabricated on this particular boat (no room between the strut and the prop...okay, maybe three quarters of an inch...not enough clearance). Good luck.

 

[Terry]

RON, THE ZINCS GO ON HARD. I USUALLY

use two hammers striking opposing sides of the zinc at the same time to ensure a snug fit. Tom's suggestion of a block is good, too. I strike with the hammers a couple of times, snug up the bolts, strike again, etc., until there is no more bolt play. When finished you should see no light through the space between the inside of the zinc and the shaft. I've done three sets this way and none have yet to come off.Good luck.Terry

 

[Ron Vanderveer]

Thanks guys

I have pretty much done what you guys have suggested, at least on this last install (Saturday). I also found some stainless steel nylon locknuts that I put on each side of the little bolt that holds the two sides together. So, we will see!Now I have to build a little periscope so I can check my zinc from topside.Thanks again.Ron