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Old 11-10-2014, 09:33 AM   #41
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Well to try and tie the drift to the original thread. Before you dive overboard in fresh water to check your zincs that do not work in fresh water be sure to check out the electrical safety of your surroundings.
And I can tell you that the zinc anodes on Florence A are as white as white can be as the boat was stored in fresh water. And I can tell you that I have had all the bottom coatings off back to bare steel because the paint was bubbling off the steel from electrolysis. Now, fortunately the damage was repairable. BUT I don't think that there will be zinc anodes on my boat when I plan to sit in fresh water for the bulk of the time.
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Old 11-10-2014, 10:27 AM   #42
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Well to try and tie the drift to the original thread. Before you dive overboard in fresh water to check your zincs that do not work in fresh water be sure to check out the electrical safety of your surroundings.
And I can tell you that the zinc anodes on Florence A are as white as white can be as the boat was stored in fresh water. And I can tell you that I have had all the bottom coatings off back to bare steel because the paint was bubbling off the steel from electrolysis. Now, fortunately the damage was repairable. BUT I don't think that there will be zinc anodes on my boat when I plan to sit in fresh water for the bulk of the time.
Hi Bryan

Zinc can only do OK anode-work in fresh water as long as their surfaces are consistently scraped/scrubbed completely clean with rigid metal scraper and stiff wire brush … like… at least every couple/few months or more often. I figure your “white” colored zincs were not regularly tended to in this way???

Magnesium removes need to keep anode surfaces clean in fresh water. It also is more costly, disappears by shedding-off much more quickly than zinc, and therefore more often needs work performed to replace the several old/then-useless Mag pieces.

I love to go under our Tolly while at anchor (never at dock or with gen set running) for tending to anode surfaces as well as check everything under boat carefully with flood light, knife, etc... during each anchor-out. Helps keep me young and healthy!

Happy Anode Daze! - Art
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Old 11-10-2014, 11:25 AM   #43
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...disappears by shedding-off much more quickly than zinc...

An easy sign to tell if your "sacrificial anode" is doing its job is when it sheds off quickly.

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The science behind the recommendations is not that difficult to comprehend. The sacrificial anodes are not very expensive when compared to brand new props, shafts and such.

Honestly, why settle for duct tape that may work out ok when condoms are proven effective and readily available? Replacement cost is a pretty silly argument.
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Old 11-10-2014, 11:51 AM   #44
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The "problem" I have is the variation between seasons. During the summer in the harbour the water conductivity, salinity and temperature is high. During the winter the temperatures drop, and fresh water from the frequent rains are on the surface so conductivity plummets.

Boat use is more frequent in the summer , less in the winter.

So my current solution is to scrape the passivating oxide off in the winter.

A better solution is to find an aluminum alloy anode that will fit my hull anode on the stern, near the surface.

Interestingly enough, the prop and rudder zincs works fine and just requires replacement. No oxide buildup. I rationalize this due to depth (more saline in the winter) and turbulence. Shrug.

But I don't want to mix anodes, so I stick with zinc alloys, or else I'm changing the rudder and prop anodes more frequently.

This would cause me to litter the ocean floor with 1/4" Allen wrenches.
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Old 11-10-2014, 12:06 PM   #45
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An easy sign to tell if your "sacrificial anode" is doing its job is when it sheds off quickly.

Attachment 34306

The science behind the recommendations is not that difficult to comprehend. The sacrificial anodes are not very expensive when compared to brand new props, shafts and such.

Honestly, why settle for duct tape that may work out ok when condoms are proven effective and readily available? Replacement cost is a pretty silly argument.
Yo, Craig... I'm not arguing at all and I know full well Magnesium works without tending to it in fresh water. And, that Mag's replacement cost is not even a real consideration... in the long run. What I am saying is that Zinc works in fresh water too as long as its surface is kept scrapped/scrubbed clean, such as I enjoy often doing to mine. The peripheries I mention such as cost and replacement schedules are pretty much meaningless... but they are fact!

For more pro-zinc items, read this thread’s post numbers: 4, 5, 7, 9, 10, 12, 13, 23, 31, 33, and… 44 for good chuckle!

Then you can read several other posts with diametrically different opinion!

YRMV!!
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Old 11-10-2014, 12:14 PM   #46
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[QUOTE=BryanF;282740]Well to try and tie the drift to the original thread. Before you dive overboard in fresh water to check your zincs that do not work in fresh water be sure to check out the electrical safety of your surroundings.
On the ESD issue. My wife and I witnessed one in Traverse City MI in August 2011. It only takes milliamps to completely paralyze you in fresh water. The dock electrical system was leaking the electricity into the water in this case. Two teens jumped off the dock to cool off and one did not come up. Tragic.
We tell everyone we see swimming in fresh water marinas of the dangers and I have posted on other forums as well.
DO NOT SWIM IN FRESH WATER MARINAS!!! PLEASE!!!!
It was unbelievable how quickly this happened....I will never forget the screams of the friends of this unfortunate youth.....
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Old 11-10-2014, 01:13 PM   #47
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One way to determine if your boat has the correct anode and is functioning as designed for your waters, is to use a silver/silver-chloride electrode with a DVM. It will tell you if you have enough or to little anode, is your bonding system working or is there stray electrical currents in the marina from a neighbors boat or from the marina, if you have a galvanic isolator or not, plugged into shore power or not can also change the requirements. You can buy a reference probe for less that $150 or hire an ABYC tech.

Depending on what source you read, Al can work in fresh, salt or brackish but without testing, which source are you going to follow?
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Old 11-10-2014, 01:27 PM   #48
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I guess that what I was trying to say. The electrolyte can be dynamic in cathodic protection using an anode. One size rarely fits all, and just because it works for your boat, doesn't mean it is going to work for others.

Sometimes we forget that around here...

PS: I'm sure someone will come up with a set and forget impressed current protection including "change anode" alarms for recreational boats soon enough, if it doesn't already exist.
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