Vanishing Zincs

[wcconway]

This post is extracted from the C350ia MAILMAN email exchange.
Original question posted by Randy Mattes, Quiet Answer II, Hull 244 "Does anyone have a problem of losing your end shaft Zinc? It seems that every time my diver goes down to clean the botttom the Zinc is gone. Is there any remedy or other type Zinc?"

Russ Peel, Avalon, Hull 150 "Do you mean "gone" as is screw come loose and whole thing fallen off including the screw, or zinc gone because it has been consumed? I fitted a new one earlier this year and after about 4 weeks had an off balance shaft and loud knocking from under my feet. When a diver checked the screw had started to unthread and the anode was swinging loosely around on the end of the shaft. He tightened it up and I haven't had a problem since, but have only run engine for about 5 hours since then. I guess if the screw is unthreading they could use Loctite, I don't know if there is one that can be applied and set underwater."

Randy Mattes "Completely gone - 2nd one this year. I'm using a CMP 204304 which is for a 1" shaft. Do you know the shaft size on a 350? Also, I saw an older post that someone used a collar Zinc which was a Camp P5. I don't see that camp makes a "P" series but they do make a "C" series. Could that just be a typo? "

John O'Connell, Second Wind, Hull 84 "I had electrolysis on the end of my shaft about three years ago and can no longer screw a zinc onto the end. What I use now is a BD-25 donut zinc. It attaches on that small area of shaft between the prop and the hull. I've gotten two seasons on this zinc and probably could get three, except that I haul out every other year to paint the bottom and just change the zinc then. Bonnie Mitchell in Florida told me about it." He also provided the attached photos.

C350IA Webmaster

[wolfe10]

From a hydrodynamic standpoint, that is less than ideal.

Have you tried Locktite on the threads of the bolt securing the ZN? Of course, if this is installed with the boat in the water, it might take a call to Locktite to determine the proper formulation.

Brett

[Triumph]

You need to really get the nose cone zinc on there tight. You have to give it all you've got. I've done this underwater too. I too lost one of these early on when I wasn't tightening them so hard. What happens is that when you put the boat in reverse, the weight of the zinc will cause the inertia to break the screw Loose and it will unscrew. I haven't lost one in 5 years now.

Bill on Triumph