Bottom Cleaning

fstbttms wrote:
I'm liking this forum. Good fun from Day One!

fstbttms,

You probably already know this, but on every forum there are a few people who just cannot be wrong no matter how wrong they actually are.* You'll never get the last word.

Best to just let them ramble on, you're not going to change them.

*

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-- Edited by rwidman on Thursday 29th of March 2012 06:33:52 AM

Oh, believe me, I know it. I spend waaay too much time in forums and have for years. I'm an old hand at this.

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-- Edited by fstbttms on Thursday 29th of March 2012 08:36:07 AM

BTW- I couldn't post this from my phone while I was out on the water, cleaning the six or eight boats I did yesterday :jawdrop: but here is a chart from the Martyr Anodes web site illustrating anode types and where they should*(and where they should not) be used. I think it's pretty clear:

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-- Edited by fstbttms on Thursday 29th of March 2012 08:54:24 AM


-- Edited by fstbttms on Thursday 29th of March 2012 08:55:25 AM

Does anyone have a Galvanic isolator on there boats or zinc saver as I like to call it.

They really do work if you have a hot harbor.

SD

It is clear that with maintenance*zinc can successfully*be used in fresh water too!
*
Following are quotes from Martyr Anodes website;*fstbttms favorite.* As I*have said and others boaters*clearly intimated... zinc works in fresh water too, especially*if its surface is kept*clean.**Page link: http://www.martyranodes.com/content/martyr-resources/about-corrosion.php*i.e. "... for example the surface of a zinc... if left in fresh water for some time become covered with an off white crust of oxide which effectively seals the anode and stops it working... It is therefore very important to check Zinc... [in] fresh water and if necessary clean [it] off..."*As I say...*Cleaning the surface of zinc enables it to continue working unabated by surface coating in fresh water.**Properly tended, Zinc can function as an applicable anode in fresh water.* If left unattended zinc will eventually cease functioning as an anode.* There is no need to change anodes in fresh water as long as zinc surface is kept clean.*

*
*Full sentrences from Myrtr Anode web page linked above:*
Not all anodes are suitable for every environment, for example the surface of a zinc or aluminum anode will if left in fresh water for some time become covered with an off white crust of oxide which effectively seals the anode and stops it working even when returned to salt water. Zinc Anodes suffer a similar problem even in brackish conditions whereas Aluminum will continue to operate effectively in river estuaries and other areas of brackish water indefinitely. The consequences of this passivity of the anode are that the next most anodic item within the anode bonding system will start to sacrifice itself which could of course be very serious.
It is therefore very important to check Zinc and Aluminum anodes after any trips into fresh water and if necessary clean off or change the anodes. Should a vessel move into fresh water for more than two weeks Martyr recommends that an alternative anode system is used suitable for fresh water situations.

skipperdude wrote:
Does anyone have a Galvanic isolator on there boats or zinc saver as I like to call it.

They really do work if you have a hot harbor.

SD

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SD - Altough our Tolly is not at a*hot harbor in our*remote*freshwater location,*and* therefore I do not require one.**I*agree with use of Galvanic Isolaters in Hot-Spots*and have been told they*work well by other boaters.

My personal opinion is that a galvanic isolator is never a bad idea. However, I also think the "hot harbor" is a wive's tale. You can go to virtually any marina anywhere and find somebody who will say it's "hot" there. I have heard this in virtually every marina I have ever worked in in the Bay Area, and I have yet to find it to be true. Marina-wide problems are rare, IMHO. That being said, if you are plugged into the shorepower system, your boat is in electrical contact with every other boat on that particular circuit and you can be sharing somebody else's electrical problems. But in reality, if you are experiencing rapid zinc depletion or corrosion issues, the most likely cause is aboard your own boat and that's the place to look first.

skipperdude wrote:
Does anyone have a Galvanic isolator on there boats or zinc saver as I like to call it.

They really do work if you have a hot harbor.

SD

I do.* I thought any boat with shorepower would have one from the factory.

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fstbttms wrote:
My personal opinion is that a galvanic isolator is never a bad idea. However, I also think the "hot harbor" is a wive's tale. You can go to virtually any marina anywhere and find somebody who will say it's "hot" there. I have heard this in virtually every marina I have ever worked in in the Bay Area, and I have yet to find it to be true. Marina-wide problems are rare, IMHO. That being said, if you are plugged into the shorepower system, your boat is in electrical contact with every other boat on that particular circuit and you can be sharing somebody else's electrical problems. But in reality, if you are experiencing rapid zinc depletion or corrosion issues, the most likely cause is aboard your own boat and that's the place to look first.

A friend of mine was told by a mutual friend and boat owner that he was moving to another marina downriver.* His diver told him that his anodes were being disolved because of electricity in the water from a train bridge about a mile up river (this is not an electric train).

I call BS, but I didn't talk to the diver personally.

If you have a problem with your anodes or underwater metal and the other boats in your marina do not, you should probably look for a problem on your own boat or possibly the individual pedestall you are plugged into.

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rwidman wrote:
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I do.* I thought any boat with shorepower would have one from the factory.

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*I made my own.

SD

rwidman wrote:
A friend of mine was told by a mutual friend and boat owner that he was moving to another marina downriver.* His diver told him that his anodes were being disolved because of electricity in the water from a train bridge about a mile up river (this is not an electric train).

I call BS, but I didn't talk to the diver personally.

*

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*I have found in the marine maintenance business, and the hull cleaning industry in particular, that there are a lot of people who don't know their ass from a hole in the ground. This guy sounds like he was one of them.

fstbttms wrote:
My personal opinion is that a galvanic isolator is never a bad idea. However, I also think the "hot harbor" is a wive's tale. You can go to virtually any marina anywhere and find somebody who will say it's "hot" there. I have heard this in virtually every marina I have ever worked in in the Bay Area, and I have yet to find it to be true. Marina-wide problems are rare, IMHO. That being said, if you are plugged into the shorepower system, your boat is in electrical contact with every other boat on that particular circuit and you can be sharing somebody else's electrical problems. But in reality, if you are experiencing rapid zinc depletion or corrosion issues, the most likely cause is aboard your own boat and that's the place to look first.

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*I wonder about that as well. However, we had our boat in a marina where we had a row of houseboats directly behind us and we experienced massive depletion of our zincs. Once we moved to a different marina the depletion dropped dramatically. We had/have shorepower in both situations.

I guess we are lucky here in the PNW. At my marina, Zinc usually will last a full year and I don't hand clean the hull. I use an ablative paint and would not be fond of brushing the paint to clean the hull. Usually an hour of running is enough to clean what little has grown, off the hull. My diver checks the hull and zinc several times during the year and replaces the zinc in March or April each year.
Larry B

rwidman said:

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Just because a zinc is disolving does NOT mean it's working.

All boats SHOULD come with Galvanic Isolators or Transformers but sadly they don't/

psneeld said:

Just because a zinc is disolving does NOT mean it's working.

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Then what is it doing if not working?

fstbttms said:

Then what is it doing if not working?

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Eroding...galvanic action...several reasons...

But if it is not enough or if there is no continuity with the metal it's attached to...then it ain't helping that metal (or helping it enough).

psneeld said:

Just because a zinc is disolving does NOT mean it's working.

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Yeah, I gotta disagree with that. Yes, it's possible that there is not enough zinc to protect adequately, but zincs don't simply "dissolve". If they are depleteing, it's because they're doing their job.

fstbttms said:

Yeah, I gotta disagree with that. Yes, it's possible that there is not enough zinc to protect adequately, but zincs don't simply "dissolve". If they are depleteing, it's because they're doing their job.

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Think about it...underwater metal is affected by galvanic action that doesn't have zinc on it and is more nobel than zinc.

So why can't zinc underwater be subject to that same galvanic action?

If the zinc is isolated from the metal it is trying to protect by corrosion or poor connection or paint...it doesn't protect but will still go bye-bye just like your rudder and props eventually.

Without a DIRECT electrical connection between the zinc and the metal it's trying to protect...the zinc in the props, etc will still start to react in a galvanic way. Even with plenty of zincs on other underwater parts...I have seen props and prop nuts destroyed because of lack of zinc.

All boats SHOULD come with Galvanic Isolators or Transformers but sadly they don't/

Yeah buy one or make one and install it.

I used two bridge rectifiers wired in sequence so the current go's in a loop wired into the green wire from shore power. mounted on a big chunk of aluminum angle as a heat sink.
About $20.00
Sd

psneeld said:

Think about it...underwater metal is affected by galvanic action that doesn't have zinc on it and is less nobel than zinc.

So why can't zinc underwater be subject to that same galvanic action?

If the zinc is isolated from the metal it is trying to protect by corrosion or poor connection or paint...it doesn't protect but will still go bye-bye just like your rudder and props eventually.

Without a DIRECT electrical connection between the zinc and the metal it's trying to protect...the zinc in the props, etc will still start to react in a galvanic way. Even with plenty of zincs on other underwater parts...I have seen props and prop nuts destroyed because of lack of zinc.

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Galvanic corrosion occurs when two dissimilar metals are in contact with each other in an electrolyte. How is this happening in the scenario you describe?

fstbttms said:

Galvanic corrosion occurs when two dissimilar metals are in contact with each other in an electrolyte. How is this happening in the scenario you describe?

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I bolded the most pertinent words in the above statement. Plumbing 101.

If there is no direct contact between the dissimilar metals galvanic corrosion will not occur.

fstbttms said:

Galvanic corrosion occurs when two dissimilar metals are in contact with each other in an electrolyte. How is this happening in the scenario you describe?

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OK...I see the point....but zincs do seem to "dissolve without that majical connection" maybe it's because they are not pure zinc but an alloy?

psneeld said:

Nevermind...you didn't think it through...otherwise you don't need zincs at all.

They DON"T have to need to be connected...just immersed...

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I suggest you Google "galvanic corrosion", because you clearly don't understand the definition of the term.

fstbttms said:

I suggest you Google "galvanic corrosion", because you clearly don't understand the definition of the term.

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Sorry long day...I wasn't thinking it through...but still feel like the whole issue of zincs doing their job is more about regular monitoring than the "wait and see appproach"...then it's too late for some.

You at least see them on a more regular basis.

An anode + a cathode + seawater = a battery.
electrons migrate.
Two disimilar metals in seawater.
One becomes the anode the other becomes the cathode.
electrons migrate ( or disolve) from the least noble metal.
Zinc is the least noble metal on your boat.
It disolves.
SD

psneeld said:

Sorry long day...I wasn't thinking it through...but still feel like the whole issue of zincs doing their job is more about regular monitoring than the "wait and see appproach"...then it's too late for some.

You at least see them on a more regular basis.

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Don't ever doubt me again.

Call me stupid believing a dissolving zinc isn't doing its job.

fstbttms said:

Then what is it doing if not working?

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It's ballast.