| Sailonner, You might be talking about the way galvanized chain typically dies, once it's going, it's gone.This is easily explained, by the increasing exposed steel surface of the chain,increasing current flow between steel and zinc.I remember galvanized trash cans, which stayed rust free for a decade or so, but once you saw the first signs of rust, the whole thing deteriorated in a matter of months. You say:"As far as I am concerned, the purpose of grounding is to create a ZERO volt reference. Neither anodic or cathodic. " This might be true for everything inside the boat, but outside, you always end up with metal with its own specific potential submerged in seawater, that has zero volts. The question was, if hooking up this "ground" to the negative battery (current source) or a big lump of lead if you want, with its own specific voltage (nobler than zinc) will INCREASE said deterioration. In my experience it does. I lived 10 years with negative grounded, with horror stories of electrolysis and another 15 years on the same boat with negative isolated from ground with dramatically less damage.
Rob --- On Thu, 3/3/11, Lonner <lon4@yahoo.com> wrote:
From: Lonner <lon4@yahoo.com>
Subject: [Electric Boats] Re: Rewiring DC electric system and Grounding
To: electricboats@yahoogroups.com
Date: Thursday, March 3, 2011, 7:04 PM
I'm no expert, but have done a fair amount of marine electrical system work. Years ago, I lived on a boat at anchor and saw the chain deteriorate rapidly, though that boat had no electrical system at all! I believe you may be dealing more with galvanic depletion of the zinc (hot dip galvanizing) This can happen when something in the nearby environment is cathodic, or receiving electron flow via ions through the salt water.
For everyone a good read here: (corrosion-doctors.org/Definitions/galvanic-series.htm)
As far as I am concerned, the purpose of grounding is to create a ZERO volt reference. Neither anodic or cathodic.
Sailonner
--- In electricboats@yahoogroups.com, rob linda <rob_linda_2000@...> wrote:
>
> Living on an anchored boat, I would like feedback on the following:Most anchor windlasses use a series (starter) motor with negative ground.The motor housing connects to the windlass, the gypsy, the chain and seawater, creating a conductive path between battery negative and the sea.It is widely believed, that this causes the galvanizing (zinc) of the chain to disappear rapidly.Reason I and many others have an extra switch in the negative windlass lead, which lives in the 'OFF' position, except when the windlass is used.On a similar note, some have an extra negative switch for the starter motor of the main engine, keeping negative and ground separated, to prevent the fast eating away of sacrificial zinc anodes etc.Both windlass motor and starter motor are typically automotive of the shelve.I have understood, that professional marine motors have their negative terminal separated from the housing (ground), for that reason.It seems to me, that an
> ELECTRIC boat forum should have a clear consensus on a simple question as :"Should there be a conductive path between battery negative and the ocean?"
> RobS/V Linda
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