Zincs and the 'Hot' Marina

[Alan Wheeler]

Nathan has very kindly apologised to me behind the scenes. Thank-you Nathan, I really do appreciate that. That doesn't mean to say that any one of us was right or wrong on the subject. Nathan, I would like to know more about it. It is obviuose that you have found a result and I too have found a result that is opposing. Either we are discussing a different point (highly possible with differences in English) or there is something more for either one of us to learn. (also highly possible)

The following is not addressed At Nathan, it is a general comment.
I want to make one thing very clear to any reader. The "Team" welcomes debate on subjects. That's how we all learn. That is the essence of this board, it is what we ultimately strive for so this Forum remains exciting and a place to learn about our common goal. I certainly don't know it all. Some subjects you will see I stay compleatly out of. But when I do participate, I aways do so with the view that I stand to be corrected. I welcome correction, so should we all or we will never learn. However, I want to make this very plain. What ever any one has to offer here is all up for debate. It is via debate that we all share and learn.
But if someone is wrong, that poster should not be ridiculed in anyway. That is a rule we as the "team" protect very dearly here. All posters should be able to post in a "safe" environment. I hope we as a "team" manage to maintain that to some degree.
So for instance, if I post something that someone else disagrees with, then by all means I welcome that poster to add their knowledge and hopefully, we all go away a little more wiser. But if someone agressively returns a post, it is only natural that the original poster is going to have there heckles raised and then the topic will take a nose dive and nobody becomes any wiser. Well......apart from maybe becomeing wiser as to what the posters attitudes are like ;-)
So please take stock of how a reply is posted. That goes for me as well. But if we are careful in our choice of words, then this place will remain a great place of learning and continue to be the place I enjoy participating in the most.

[EngNate]

I'll second that. Y'know, there's a lot of well-documented, yet contradictory information out there, and a lot can be lost through small missing details or 'syntax errors'. One thing, I think, is certain, electrons have no emotions, no philosophy, no regard for anyone's position in life, and if we go off on these tangents we defeat our purpose.

[Pura Vida]

Well I have to say thanks to every body who has posted so far. Now that I have managed to get rid of that pesky job for a while I'm headed down to get the boat ready for some quality time. Tomorrow I plan on trying out the meter test and see what I can learn. Now as an old british car and bike nut I have only one question remaining... are the old C&C's postive ground?

[seafox]

One thing, I think, is certain, electrons have no emotions, no philosophy, no regard for anyone's position in life

Electron, single, energised, seeks one way trip with yacht owner. No emotions or strings attached.

[Ex-Calif]

seafox - forgot to advise the attitude. Is this a positive or negative electron?

I've had it with negative attitudes on the boat. Can spoil the whole passage.

[seafox]

it's looking to cruise so I suppose it is a positive one

[Pura Vida]

Well I did a few tests day before yesterday and came up with another question. I removed the bonding from one of my bronze thru hulls (head outlet) and did the test. I received a number in the 880 range indicating stray current. So here is my question. If the bronze fitting is not connected to any conductive part how is the electrolysis occuring?

[Maddog]

Alan - Your magnanimity is only surpassed by your number of posts. I'm glad we are all freinds again.

(My wife made me throw out the Word Power tapes last week. The dinner conversation was becoming too obtuse and contained antagonistic proclivities.)

[Alan Wheeler]

Why use a big word when a Deminuative one will suffice :-)

I have been talking to Nate in the background. I understand where it all went wrong. I was my poor communication. Way back when all this got a little tense, I made a comment about the fact that a current could flow, even though Zincs were on each hull. What Nate understood from that was two opposing Zincs would form a battery, which is incorrect. Where I was coming from was even if both hull s have a Zinc, differences such as maybe one zinc being more worn than the other, or one hull having more metal to protect than the other and other similar variations, would mean that one hull would have a different voltage potential in the water than the other. Even water temp and Salinity could have an impact. So even with a Zinc on each hull, it is still possible to have an electrical current flow between the two hulls.
Gee I do hope that was clearer.

[GordMay]

See ABYC Sections “E-2" (Cathodic Protection) and “E-11" (AC & DC Electrical Systems)
E-2: https://www.abyc.com/committees/E-02.pdf
E-11: https://www.abyc.com/committees/.%5CE-11.pdf

Specifically, the Reference Voltages in Table 1 (page 7):
https://www.abyc.com/committees/E-02.pdf

Fluke has a short tutorial on Corrosion Testing at:
http://www.fluke.com/Application_Not...r/B0269b_u.pdf

And another, on testing Engine Electrical Systems at:
http://assets.fluke.com/appnotes/ele...r/B0270b_u.pdf

[Pura Vida]

Thanks Gord.

[hellosailor]

Wheels-
"So even with a Zinc on each hull, it is still possible to have an electrical current flow between the two hulls. "

Well, you stick two pieces of metal in an electrolyte, and you've got a battery and you will have the potential for current flow. Ideally you use different kinds of metal...but even two "pieces of zinc" could be different enough, when all is said and done, to create SOME potential.

OK, maybe it will only power a hearing aid that way...< G >... but considering how carefully scrap metal companies mix the alloy types that become boat zincs?<G>

I wonder if we could use a stack of US pennies instead. They've been copper-clad zinc for a long time now. Hang a bag of pennies over the rail, keep the hull clean and power the hearing aids at the same time, eh?

Just makes me appreciate Marelon thruhulls all the more!

[stevemac00]

Do I need to be concerned about this in freshwater (Great Lakes)? I'm installing a Freedom Inverter which requires me to electrically bond the AC and DC grounds. Just to be safe I plan on installing the Yandina (capacitor-less) galvanic isolator but wondered if it's really necessary. Hope you find this still on topic.

[S/V Elusive]

Steve - It is only needed in Sea Water (metal content). I'm pretty sure the Great Lakes have reduced most of their metal content .. haven't they?

[EngNate]

Pura Vida: To confirm what you are reading is stray current (the value 880 is borderline, some really hi-grade bronze may read this high) (assuming you are reading DC), move your zinc probe to different locations around the boat and test. The reading will change if there's stray current, and if there is no connection to the fitting except the meter, that current is in the water and can be from your boat or another. On confirming stray current, disconnect all your batteries and turn off the charger(s) (if reading DC) or the shore cord (if reading AC) and re-test. If the voltage goes away(AC) or falls to expected value for the fitting(DC), you have a fault on your boat. If it remains the same, the fault is on another boat (Possibly includes a fault(s) on the dock if AC). You can find the source by going along the dock and measuring between the grounded outlet boxes and your probe in the water close to a potentially (no pun intended) suspect boat. Where you find the highest reading, start unplugging boats - let someone know if anyone is aboard, and turn off the dock breaker before unplugging. When you pull a plug and the meter reading drops significantly, you've found a problem boat, and don't be too surprised if there's more than one.