Regal 53 SC Owner's Manual page 424

ZEUS STERN DRIVE MAINTENANCE
Corrosion Facts and Tips
On the drive unit unit there are 2 or more dissimilar met-
als. When the drive is submerged in a conductive solution
such as saltwater, brackish or polluted water with a high
mineral content a chemical reaction takes place causing
electrical current to fl ow between the different metals.
The electric current fl ow called electrolysis or galvanic
corrosion causes the metal that is most chemically active
or anodic, to erode. This process in time will cause the
need to replace power package components exposed to
water.
The Cummins MerCruiser Zeus propulsion package uses
anodes to help protect against moderate galvanic corro-
sion. The Zeus unit features a MerCathode System which
along with sacrifi cial anodes will provide corrosion pro-
tection under ordinary conditions. Boats connected to AC
shore power such as your vessel require additional protec-
tion to prevent damaging low-voltage galvanic currents
from passing through the shore power earth ground wire.
As standard equipment your Regal yacht features a 60
amp galvanic isolator installed to block the passage of
galvanic current while providing a path to ground for the
dangerous fault (shock) current. See the galvanic isolator
in this manual for further information.
Furthermore, if your yacht incorporates the isolation
transformer it does not allow the neutral ground conduc-
tor on board as it makes its own neutral through a mag-
netic induction process and therefore is not suspect to
galvanic corrosion because that pathway is not available.
Sacrifi cial anodes are mounted on the drive trim tab. Also,
there is a set mounted on the vessel's transom under the
swim platform along with the trim tabs. These need to be
checked at least every 6 months and if 50% corroded they
need to be replaced.
MERCATHODE
CONTROLLER
The MerCathode system uses an electrode and an anode
assembly to help protect against galvanic corrosion. The
MerCathode electrode and anode are mounted to the
composite cover on the underside of the drive.
The controller is mounted on the transmission. The sys-
tem needs to be periodically tested to ensure adequate
output. Contact a Cummins MerCruiser Diesel Autho-
rized Repair Facility.
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Chapter 8