Re: TWL: Zinc protection
Subject: Re: TWL: Zinc protection
From: Ancora (ancora@XXX.XXX)
Date: Wed May 01 2002 - 10:20:14 EDT
We have the Electro-Guard system on Ancora. The vessel has only the two
large plate zincs on the transom, none on the underwater gear. With
Electro-Guard the plate zincs last a lot longer than without, and I can
monitor the underwater conditions and adjust accordingly. Usual disclaimers.
----- Original Message -----
From: "Arild Jensen" <elnav@XXX.XXX>
To: "trawlerworld list" <trawler-world-list@XXX.XXX>
Sent: Friday, May 03, 2002 5:32 AM
Subject: Re: TWL: Zinc protection
> > > Doug Hoople wrote:
> >I'm not a fan of electrical controllers, as they often cause more harm
than good. A wood boat's
> > electrical system is an ecosystem that requires balance, and that
balance is achievable organically,
> > if you will. I liken the electrical controllers to the use of chemical
pesticides and herbicides in
> > farming. They create unintended side-effects, and cause more harm than
good unless understood at an
> > extraordinarily nuanced level.
>
>
> REPLY
> I'm inclined to agree, based on my own observations in the field.
> However, I would like to clarify one thing. There are two kinds of
"electrical" controller systems.
>
> The active kind that "impresses" a counter voltage onto the bonded
fittings.
> This is the one that is really prone to causing damage if a malfunction
occcurs.
>
> The other kind is "passive" in that it does not actively control the
amount of protection current
> flowing from the zinc to the under water fittings.
> It consist of a resistor placed in series between the zinc and the
bonding wire connecting the
> fittigns to be protected.
>
> A millivolt meter is permanently connected to read the voltage on the
bonding wire referenced to
> a cell ( usually silver - silverchloride )
> One company - ElectroGuard - uses a zinc instead of a silver
silverchloride cell but that is
> another story.
>
> By monitoring the voltage, you can adjust the resistor to give you exactly
the right voltage to
> neutralize the galvanic potential created by the dis-similar metals in
the water.
>
> This is perhaps more convenient that having to place the silve cell over
the side and having to
> connect your test meter to each fitting or the bonding wire.
>
> With a passive system, the only risk of failure is if the bonding wire
breaks, corrodes or the
> meter itself fails, or the zinc completely erodes away. Presumably,
periodic inspections as a
> normal part of boat maintenance would reveal these deficiencies long
before a catastrophic
> failure occurs.
>
> The passive system is litttle more than a permanently installed test meter
and a means of
> adjusting the zinc size to suit your boats under water fittings.
> It has the additional advantage of making convenient, frequent,
inspections possible.
>
> regards
>
> Arild
