Where are zinc's on a v-drive?

[glocklt4]

Was thinking about this tonight after reading about the frequency of zinc changes on a boat that's wet slipped all year round. Obviously the drive has it on a stern drive, but where are they on the v's? Wondering if there is any way to replace them myself while in the water at all, or if it's really required to have a haul out. I would guess somewhere around the output shaft of the drive, but I have never been under one to see.

 

[Alex D]

My 340DA has zincs on:
Tabs One on each
Transom
Shafts
Hull

My zincs were all glazed over because they are ineffective in fresh water, so I changed the transom plate and the tab anodes to magnesium anodes. the shaft and hull anodes are still the orignal zincs but completely glazed over and inactive.

 

[EKM]

Pic attached....

 

[glocklt4]

My 340DA has zincs on:
Tabs One on each
Transom
Shafts
Hull

My zincs were all glazed over because they are ineffective in fresh water, so I changed the transom plate and the tab anodes to magnesium anodes. the shaft and hull anodes are still the orignal zincs but completely glazed over and inactive.

Interesting... So zinc's are there to be sacrificial anodes, so does that mean that all of the places you mentioned that they are attached are metal? Wouldn't make sense otherwise because an electric charge wouldn't go through the fiberglass hull nearly as easily.

Also, i hadn't read that zinc didn't do anything in freshwater.

 

[glocklt4]

Pic attached....

Cool, thanks! Pretty messy .

So is that one wrapped around the drive in the middle, or is that a joint between the prop and output shaft from the v-drive?

 

[Alex D]

Interesting... So zinc's are there to be sacrificial anodes, so does that mean that all of the places you mentioned that they are attached are metal? Wouldn't make sense otherwise because an electric charge wouldn't go through the fiberglass hull nearly as easily.

Also, i hadn't read that zinc didn't do anything in freshwater.

The tab and shaft anodes are attached to metal of course. The transom plate and the hull anodes are not. They are attached to the bonding system, which is designed to be electrical protection (grounding via the hull plates and water) as well as galvanic corrosion protection for all bonded gear in the bilge.

 

[glocklt4]

The tab and shaft anodes are attached to metal of course. The transom plate and the hull anodes are not. They are attached to the bonding system, which is designed to be electrical protection (grounding via the hull plates and water) as well as galvanic corrosion protection for all bonded gear in the bilge.

Gotcha, thanks!! How often do you replace yours being in fresh water?

 

[Alex D]

Gotcha, thanks!! How often do you replace yours being in fresh water?

the zincs will glaze over and never need replacement, i just changed the tab anodes and the transom plate two weeks ago and we'll see. I expect to have to change them every year. If they erode too fast I am going down to aluminum anodes for the transom plate and tabs. Zinc is just a plain waste in fresh water.
I would not change the shaft and hull anodes cause I cannot dive them and would have to pull the boat, so I'll leave them. In Our super clean freshwater lake most boaters don't even do anode maintenance.

 

[CJ Martin]

My 320DA has three - one on each tab, and a big heavy one on the transom. No shaft zincs, not recommended by my yard. I'm in brackish water, and replace them every spring prior to launch.

I am curious about your 340 Alex, as a slipmate has a 2001 340DA and he seems to be set up just like me. Where is your hull zinc? Or did you accidently count the transom zinc twice? It sure is heavy enough to count as more than one.

-CJ

 

[glocklt4]

Do you have a picture of the hull zinc? I'm curious exactly where that is.

 

[DukesFin]

Here is a picture of the BRICK on the transom/hull of a 340:

 

[glocklt4]

Thanks for the pic. That helps a lot. It looks like you have a zinc at the very end of your prop tip (judging by the color being the same as the brick at the back). Is that right?

Pretty weird to me to have a zinc attached to something non-metal like that brick at the back. I guess it works though...

 

[Alex D]

My 320DA has three - one on each tab, and a big heavy one on the transom. No shaft zincs, not recommended by my yard. I'm in brackish water, and replace them every spring prior to launch.

I am curious about your 340 Alex, as a slipmate has a 2001 340DA and he seems to be set up just like me. Where is your hull zinc? Or did you accidently count the transom zinc twice? It sure is heavy enough to count as more than one.

-CJ

There are hull zincs just forward of the underwater exhausts. If you look into the bilge you will see bonding wiring attached seemingly to the hull just forward where the underwater exhaust go through the hull. These bonding wires actually attach to the outside hull zincs.

 

[Alex D]

Thanks for the pic. That helps a lot. It looks like you have a zinc at the very end of your prop tip (judging by the color being the same as the brick at the back). Is that right?

Pretty weird to me to have a zinc attached to something non-metal like that brick at the back. I guess it works though...

Like I said before! These are zincs for the bonding system that protect ALL metal INSIDE the hull that is permanently in touch with the raw water and that are connected to the bonding system.

 

[glocklt4]

Like I said before! These are zincs for the bonding system that protect ALL metal INSIDE the hull that is permanently in touch with the raw water and that are connected to the bonding system.

Ah ok. I was not sure what the bonding system was, but if there is a wire inside connected to metal parts that makes contact with the zinc outside then that makes sense. Sorry about the confusion!

 

[CJ Martin]

Interesting - My 320DA doesn't have those. I'll have to take a better look at that 340DA when he hauls out for the season. I am 99.9% sure my underwater exhausts are connected to the transom zinc - I seem to remember that being pointed out during the survey. Do you know if that was the way your boat came from the factory? My 320DA is also a '02, so I'm quite curious about this.

-CJ

 

[wkearney99]

Thanks for the pic. That helps a lot. It looks like you have a zinc at the very end of your prop tip (judging by the color being the same as the brick at the back). Is that right? Pretty weird to me to have a zinc attached to something non-metal like that brick at the back. I guess it works though...

It's more likely coincidence that the nuts holding the props onto the shafts are the same color as the zinc. Same growth probably. The nuts are certainly not designed to be anodes.

The large zinc is connected inside the boat by wires to the rest of the boat's bonding system. This provides a route for any stray voltage to take. That way the zincs gets eaten up before any of the more expensive items. This also gives you an easier place to see whether there's more corrosion that there should be. If you know to look it's easier to see it happening on a single big zinc like that instead of all the other bits of metal like your seacocks or through hulls. Better to have an $80 zinc rot out than have the seacocks get weakened, break and end up sinking the boat. So when servicing the zincs also be sure that your bonding wires are all attached properly and in good shape.

 

[glocklt4]

It's more likely coincidence that the nuts holding the props onto the shafts are the same color as the zinc. Same growth probably. The nuts are certainly not designed to be anodes.

The large zinc is connected inside the boat by wires to the rest of the boat's bonding system. This provides a route for any stray voltage to take. That way the zincs gets eaten up before any of the more expensive items. This also gives you an easier place to see whether there's more corrosion that there should be. If you know to look it's easier to see it happening on a single big zinc like that instead of all the other bits of metal like your seacocks or through hulls. Better to have an $80 zinc rot out than have the seacocks get weakened, break and end up sinking the boat. So when servicing the zincs also be sure that your bonding wires are all attached properly and in good shape.

Good advice, thanks!