Zinc in fresh water ?

[ndutton]

Yup, makes sense. I suggest matching the wire gauge of the grouper as a minimum. You don't want to add any resistance to the system.

[jpian0923]

Is that alligator clip on there worth keeping? Or should I change it to some other more permanent connector?

[ndutton]

This is intended to be easily removed before a sail and easily connected after a sail. As such, I'd keep the clip. The easier it is to do, the more often it will be done.

[jpian0923]

So, leaving it connected, in the stern locker, while I sail, isn't a good idea?

[ndutton]

Sure, that's no problem as long as it's not connected to the shaft!

Are you thinking this will be a permanent feature? I thought it was a temporary measure until the prop nut zinc got installed. Did I misunderstand or has something changed?

[ILikeRust]

You know, my boat came with a zinc "flying saucer" on a wire. Basically the same thing as the grouper, but in a chubby disc shape.

I was under the understanding that it was for "supplemental" protection when you're in a marina, as marinas are notorious for being "hot" zones due to all the electricity at the docks, and boat chargers that might not be correctly wired, or bonded to the through-hulls.

Did it come with instructions?

I know, I know - you're a guy; we don't read no steenkin' instructions. But maybe you can humor me and make and exception in this case.

[ndutton]

(Imitating DeNiro)

You talkin' to me?

[ILikeRust]

Nah, I'm tawkin' to da guy whut just got hisself a grouper zinc thing.

[ndutton]

Good thing. I was afraid I was going to have to make up some phony explanation.

Baffle 'em with BS, y'know?

[ILikeRust]

Well, yeah, but yer not supposed ta come right out and say so!

[jpian0923]

Neil, If I don't have to get under the boat to put a zinc on, I won't. (water is cold here in so-cal).

So, it could be permanent but since I've learned my lesson on zincs and hull cleaning, and losing props, I'm planning to get my hull cleaned monthly. This means a diver will install a zinc as needed...and check the prop and prop nuts as well.

Although this will occur monthly, I want assurance that my prop is protected from galvanic corrosion. Leaving nothing to chance, I think.

Bill, no instructions. Like you said though, who needs instructions?!

[kiskadee]

Although free AC power is available, I don't plug in. My zinc still only lasts 8 or 9 months. Our marina lies over an area where warships were decommissioned following WW2. A great deal of metal was thrown overboard, including many large coils of steel cables. The bottom, although covered in silt, is full of metal. Luckily we have a member who will dive and install zincs for $10 each.

I've seen stray currents of up to 10 mAmps caused by faulty refrigerators or automotive battery chargers. Without a galvanic isolator you'll never know how the boat next door is going to affect you. Luckily Atomic 4 reversing gears are pretty bullet proof, but I've heard of other engines having problems from the loss of less noble metals inside their transmissions.

In fresh water I'd use zinc or magnesium. I agree that a prop-nut zinc is best if you can't fit one around the shaft. A friend's boat didn't have room for a prop-nut zinc, so he hacksawed the sides off a donut zinc to make it narrow enough to fit between his cutlass and prop.

Even if you don't think your boat needs a zinc, install one. It'll be a cheap one-time purchase if it's not needed. It'll sit there forever, just waiting to shed electrons if something changes. Good cheap insurance.

[fstbttms]

Originally Posted by roadnsky

I'm in fresh water.
My zinc is 6 years old and looks almost new.
I'm also on Shore Power.

Just lucky?

Umm.. no. Your zinc is not working. If it were, it would not last 6 years. As previously stated, you should only use magnesium or aluminum anodes in freshwater.

[fstbttms]

Originally Posted by jpian0923

I hate to stir the pot but, can anyone comment on "In a marina you can hang zincs over the side. They don't have to be attached to your metal parts."

A zinc (or any other type) anode that is not in direct electrical connection with the part it is inteded to protect is nothing more than a piece of metal in the water. It is protecting nothing.

[roadnsky]

Originally Posted by fstbttms

Umm.. no. Your zinc is not working. If it were, it would not last 6 years. As previously stated, you should only use magnesium or aluminum anodes in freshwater.

I spoke to the PO the other day about this and he told me it isn't zinc, it's magnesium.
But... it still looks practically new.

[fstbttms]

Originally Posted by roadnsky

I spoke to the PO the other day about this and he told me it isn't zinc, it's magnesium.
But... it still looks practically new.

Well, I'm no electrician, but the anode should deplete. It's supposed to and if it doesn't, it isn't doing its job.