Hey Chris, correct me if I am wrong but don't Vega's with combis have
no transmission and no room on the shaft for shaft zincs? Trev (Mystic
Rose V2915)
________________________________
From:
AlbinVega@yahoogroups.com [mailto:
AlbinVega@yahoogroups.com] On
Behalf Of Chris Brown
Sent: July 5, 2007 7:43 PM
To:
AlbinVega@yahoogroups.com
Subject: RE: [AlbinVega] zincs and community
The sacrificial anode is sometimes called a "guppy." There is a
commercial
version sold that is actually cast in the shape of a fish, but it is
nothing
more than a piece of zinc with a long insulated wire attached and a
large
alligator clip.
Actually to protect the shaft and prop it has to be connected to the
shaft,
not the engine. The reason being is that the shaft is actually isolated
from
the engine by the transmission oil (I know, I didn't believe it either,
but
I demonstrated it once with a meter). Also if you have a coupler, like
the
Centaflex, the shaft is then isolated with a rubber bushing. Attaching
to
the engine would do nothing.
To connect the zinc to the shaft requires a "shaft brush." There are a
several types available and I think even West sells one of them. One
requires mounting a tempered shaft to the hull and then a piece of
carbon,
like an engine brush, is pressed against the shaft. I once used one that
actually wrapped around the shaft and was then tensioned by a spring
that
was attached to the overhead - easier to install I guess but more
expensive.
Both have a wire attached which is then attached to the guppy or the
bonding
system.
That's another thing to consider -- whether the bronze thru-hulls are
bonded. The ABYC recommends this as the standard practice. It is nothing
more than wire going to each thru-hull and then to the grounding system.
Personally I don't bond as I don't think the thru-hulls will be attacked
if
they aren't connected. Also there is an argument to be made that bonding
with a passive system isn't that great. There are actually active
systems
available they induce a neutralizing current into the bonding system.
But
this is expensive. At the very least it requires checking with a meter
and
what is called a "silver silver chloride half cell." If you really want
to
get into it, you can buy the cell alone for use with your multi-meter
for
about $150 or so, give or take.
Now the big kicker. If you don't leave your shore power hooked up all
the
time, then this electrolysis won't happen as there is no return path at
least that is what I believe and do. Stray current will be in the water,
but
it can't go through the prop or shaft as it has no where to go. Sure the
zincs will be eaten by galvanic action, but this probably can't be
avoided
anyway. This is much slower than electrolysis anyway, usually.
Best advice is Steve's - just go sailing (and check the shaft zinc every
few
months or so).
From:
AlbinVega@yahoogroups.com mailto:AlbinVega%40yahoogroups.com
[mailto:
AlbinVega@yahoogroups.com mailto:AlbinVega%40yahoogroups.com ]
On Behalf
Of Trevor Leech
Sent: Thursday, July 05, 2007 11:44 AM
To:
AlbinVega@yahoogroups.com mailto:AlbinVega%40yahoogroups.com
Subject: RE: [AlbinVega] zincs and community
Apparently the sacrificial anode needs to be directly hard-wired to
something like the engine block in your boat in order to protect your
prop/shaft etc. from electrolytic corrosion. Trev (Mystic Rose - V2915)
________________________________
From:
AlbinVega@yahoogroups.com mailto:AlbinVega%40yahoogroups.com
mailto:AlbinVega%40yahoogroups.com
[mailto:
AlbinVega@yahoogroups.com mailto:AlbinVega%40yahoogroups.com
mailto:AlbinVega%40yahoogroups.com ] On
Behalf Of Victor Schreffler
Sent: July 5, 2007 2:56 AM
To:
AlbinVega@yahoogroups.com mailto:AlbinVega%40yahoogroups.com
mailto:AlbinVega%40yahoogroups.com
Subject: [AlbinVega] zincs and community
As I understand the whole electrolysis discussion, the greatest threat
is when you are at the marina where stray electricity from a variety
of sources can attack your metals. What would happen if you hung a
chunk of zinc from the end of your dock--would it help not only your
boat but also help protect others around you?
Victor Schreffler
Blue Fin
Vega 1553
