H.-.11. Stray.current.corrosion; General; Galvanic.corrosion; Corrosion.prevention - Four winns 348 vista Owner's Manual

The.entire.120.(220).volt.circuitry,.especially.the.shore.
power.cord,.should.be.seasonally.tested.for.proper.
continuity.by.an.experienced.marine.electrician..This.
will.help.detect.any.short,.open.wire,.or.ground.fault...
Also,.check.the.polarity.indicator.system.for.proper.
operation.
0 (0) volt AC electrical power can be
dangerous. DO NOT attempt to service a
system unless you are familiar with, and
experienced in, performing such service.
H - 11 STRAY CURRENT CORROSION
A. General
Electrically.induced.underwater.corrosion.occasionally.
affects.boats.and.their.related.components...This.is.
referred to as "Stray Current Corrosion" and appears
as.surface.pitting.or.deterioration..Stray.current.
corrosion.is.the.decomposition.of.chemical.com-
pounds.by.electric.current...
Stray.current.corrosion.can.be.caused.by.surrounding.
boats;.an.improperly.wired.battery/charger.installation.
or.other.boats.that.are.in.close.proximity.which.have.
electrical.power.leakages..Stern.drive.units.are.
especially.vulnerable.to.stray.current.corrosion.
.
Periodically.inspect.the.engine.components.to.deter-
mine.if.corrosion.damage.exists..If.stray.current.
corrosion.damage.is.found,.determine.and.correct.the.
cause.of.the.stray.current.to.prevent.further.damage...
Consult.an.experienced.marine.electrician.or.contact.
your.Four.Winns.dealer.for.assistance.
The.use.of.some.shore.power.battery.chargers,.while.
the.boat.is.in.the.water.and.the.battery.is.connected.to.
the.system,.can.cause.stray.current.corrosion..Have.
an.experienced.marine.electrician.review.any.battery.
charger.installation.to.ensure.a.stray.current.corrosion.
problem.will.not.develop..An.improper.battery.connec-
tion.is.a.common.cause.of.stray.current.corrosion..
NOTICE
Use only UL Marine-ignition protected battery
charger(s) designed to meet US Coast Guard
regulations for external ignition protection.
Electrical Systems - Section H
Corrosion.is.usually.more.prevalent.in.polluted.or.salt.
water.than.in.fresh.water..It.is.also.more.likely.to.occur.
when.dockage.is.in.an.area.with.steel.piers,.large.
metal.boats,.or.where.shore.power.is.in.use.
B. Galvanic Corrosion
Galvanic.corrosion.results.from.a.potential.electrical.
difference.existing.between.dissimilar.metals.im-
mersed.in.a.conductive.solution.(e.g.,.salt.or.brackish.
water)..If.these.metals.touch.or.are.otherwise.electri-
cally.connected,.this.potential.difference.produces.an.
electron flow between them. The attack on the more
active.metal.is.usually.increased.and.the.attack.on.the.
less.active.metal.is.decreased,.as.compared.to.when.
these.metals.are.not.touching.
C. Corrosion Prevention
Anticorrosion.anodes.are.attached.to.the.bottom..
of.the.gimbal.housing.of.your.stern.drive.or.to.the.
transom.and.propeller.shafts.(inboards.models)..
to.prevent.corrosion.to.your.electrical.systems.and.
underwater.parts..These.anodes.will.be.slowly.eroded.
away.by.galvanic.action.and.require.periodic.inspec-
tion..Please.refer.to.the.section.on."Anti-Corrosion.
Anodes" in your engine manufacturer's manual for
additional.information..See.Figure.H-2..
Transom
Anode
Figure H-2: Inboard Transom & Shaft Anodes Shown
Shaft
Anode
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