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Old 08-02-2011, 23:02   #16
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Bill, engines typically have pencil zincs mounted in the block itself to protect it from corrosion. What is being discussed here is a 'band-aide" method of providing protection, not only to the engine, but running gear as well. Clipping a long wire with a zinc on one end (hanging in the water) to some part of the engine, shaft or rigging (if the rig is bonded) may provide some protection, but is not the ideal method of corrosion control by any means.
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Old 08-02-2011, 23:08   #17
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Okay another question, even though I have zincs on my shaft that are supposed to take care of this problem, is there still a good chance that I'm still getting electrolysis to my engine/transmission, as in its not really fool proof right?
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Old 08-02-2011, 23:09   #18
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is the pencil zinc mounted to the engine submerged?

is that the primary system and teh 'wired system' a 'secondary'?

seems everything is going to be done like that anyways, as you can't mount zinc to everything...

again, I see 'redundant' in the multiple grounding busses' so, maybe you cant have enough zinc?
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Old 08-02-2011, 23:10   #19
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Okay another question, even though I have zincs on my shaft that are supposed to take care of this problem, is there still a good chance that I'm still getting electrolysis to my engine/transmission, as in its not really fool proof right?
Why would there be a good chance of this happening? Are you speculating or is there evidence of corrosion on your engine?
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Old 08-02-2011, 23:13   #20
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is the pencil zinc mounted to the engine submerged??
In the cooling system.

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is that the primary system and teh 'wired system' a 'secondary'??
Yes, as far as engine protection goes. Hanging a zinc over the side is a stop-gap measure and not standard procedure.

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maybe you cant have enough zinc?
Just the opposite. It easy to have too much zinc, especially on a wooden boat.
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Old 08-02-2011, 23:15   #21
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Not anything noticeable, but my question was more from my curiosity than anything. The more I know about how to preserve my engine the better.
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Old 08-02-2011, 23:16   #22
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Old 08-02-2011, 23:18   #23
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Quote:
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In the cooling system.


Yes, as far as engine protection goes. Hanging a zinc over the side is a stop-gap measure and not standard procedure.


Just the opposite. It easy to have too much zinc, especially on a wooden boat.
Can you explain how you can have too much zinc?
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Old 08-02-2011, 23:20   #24
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Not anything noticeable, but my question was more from my curiosity than anything. The more I know about how to preserve my engine the better.
Well, if your engine uses pencil zincs, obviously the best thing to do is make sure they are not depleted and replace them if they are. Again the guppy zinc over the side is really just a band-aide.
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Old 08-02-2011, 23:26   #25
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Well, if your engine uses pencil zincs, obviously the best thing to do is make sure they are not depleted and replace them if they are. Again the guppy zinc over the side is really just a band-aide.
I dont have pencil zincs. I have a yanmar 3HM35F, which is fresh water cooled unlike the 3GM30 I had on my other boat that required them.
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Old 08-02-2011, 23:28   #26
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Can you explain how you can have too much zinc?
A galvanic cell (formed when a zinc anode is attached to a prop shaft, for instance) causes the water around it to become alkaline. This can damage some anti fouling paints by blistering them. This is exacerbated when too much zinc is used. In wooden boats, this excess alkalinity can actually destroy wood around the metal fitting being protected.
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Old 08-02-2011, 23:30   #27
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I dont have pencil zincs. I have a yanmar 3HM35F, which is fresh water cooled unlike the 3GM30 I had on my other boat that required them.
In that case, if hanging a zinc over the side gives you peace of mind, then you may as well do it.
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Old 08-02-2011, 23:31   #28
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ok, sorry, i misunderstood.. i didnt read that the zinc was just wired and 'hung over the side'.

I had thought the zinc was mounted to the hull, and everythign was wired inside the hull and then connected to teh mounted zinc..(the mounting stud for the zinc was a through bolt of some type)


If there is a zinc mounted to the prop shaft, isnt that connected to teh motor? and if the motor is bonded/grounded, isnt everything eventually connected to at least one zinc .. probably several...

likei said originally, i figured that the closer the zinc is to the object it is trying to save the better..

the only 'bad' thing i can think of is that multiple 'grounding' points affects electrical equipment, as ground is 'relative'...
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Old 08-02-2011, 23:38   #29
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I guess I should clarify: In my case, I wired the zincs directly to the saildrive housing as close to the driveleg as I could, through a porthole and then into the water.

I have no idea if they actually helped, I only know that two months later the drives, shafts and props were OK.

This is certainly not a desirable method -- purely stopgap, and perhaps useless. I'm only saying that you're not alone in trying!

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Old 08-02-2011, 23:40   #30
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ok, sorry, i misunderstood.. i didnt read that the zinc was just wired and 'hung over the side'.

I had thought the zinc was mounted to the hull, and everythign was wired inside the hull and then connected to teh mounted zinc..(the mounting stud for the zinc was a through bolt of some type)
Larger powerboats (and some Taiwan-built sailboats) have zincs mounted on the hull. But these are never intended to protect more than one or two items. Protection is a factor of anode surface area and typically you would have a zinc or two on the prop shaft, another on the strut, in powerboats you find them on the rudders and trim-tabs etc., etc. Never is it one big zinc to protect everything that needs protecting.

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If there is a zinc mounted to the prop shaft, isnt that connected to teh motor? and if the motor is bonded/grounded, isnt everything eventually connected to at least one zinc .. probably several...)
Not everything in the boat requires protection. But all underwater metals should be protected. If you take the prop, shaft, tranny and engine into account, the realtively small shaft zincs do not have enough surface area to protect it all. And again, the length of the electrical path is a factor.
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