changing zincs on prop shaft?

[centerline]

as many zincs as ive changed on my boats over the years, this actually embarrasses me to ask such a simple question, but i want to make sure i get it right the first time....

always before, my powerboats boats have had several zincs installed on the several protuberances that was available to attach to...(trim tabs, bronze rudder, prop shaft.. or outdrive) if one didnt get a good bond, another was there to help out...

now.. with the sail boat I have only the prop shaft that sticks out and i have a spot for one zinc on it. and the one zinc that is there is no longer active for some reason...

so other than removing the old zinc, sanding the shaft with emery cloth and installing a new zinc, are there any other methods i should employ to insure its bonded well?

 

[Ralph Johnstone]

The Big Question Here Is ..............

the one zinc that is there is no longer active for some reason...

................. what leads you to believe it's not active ?

Assuming you have the proof that it's not active, does your one zinc have the two small contact balls to ensure a good electrical contact is made between the shaft and the zinc. ?

 

[Tom J]

When I'm scrubbing the waterline, I'll also dive on the zinc and scrub it with a coarse pad or stiff brush. A clean zinc is an active zinc!

 

[Rich Stidger]

I do what you do. I remove the old zinc, sand and clean, and attach the new one. Some zincs just get tightened, others like a smack with a hammer to ensure contact. Instructions with the new zinc will declare the procedure.

And, FWIW, I just use one zinc on the shaft. However my feathering prop has it's own zinc.

 

[srhummer]

A lot of people do not like them but I have been using a zinc fish over the side for the last 4 years. Easy to pull up clean off and check for how much is left. When it starts getting low I get a new one and add it over the side. I clip them to my shrouds to ground them. I have noticed my shaft zinc lasts longer, but the fish goes faster as the shaft zinc gets smaller. Since I am on the bay and it is brakish I started using Aluminum this year - too soon for a report on how that has gone.

 

[spraygun]

For what it is worth. We were cruising the ICW in South Texas a few years ago. To make a long eventful story short. We heard a pop and then the engine raced. We jumped out with a light and dove into the water. Our propeller shaft had snapped right in half before the strut. We keep a zinc installed on the propeller shaft before the strut and after the strut. The only thing that was holding on that pricey feathering prop was that zinc. My point is ,you can never have enough zincs.