52
Electrolytic Corrosion
To protect the propeller and underwater equipment
against galvanic corrosion your boat and its propulsion
unit have galvanic corrosion protection. Leakage
current from the electrical system will prevent this
protection system from working and may result in major
damage to your boat or other boats in your vicinity.
Leakage current from the electrical system can be
caused by faulty equipment or incorrect installation of
electrical equipment.
Caution!
Electrolytic corrosion as a consequence of
leakage currents may cause serious damage to
your boat’s equipment within a short time. Work
on the boat’s low voltage circuit should only be
carried out by qualified/experienced personnel.
Installation or work on the shore power equip-
ment must only be carried out by electricians
authorized to work with high voltage installa-
tions.
The following should always be observed: Route and
clamp electric cables so that they will not be exposed to
damp or bilge water in the keelson. The main engine
switch must be connected to the positive (+) terminal on
the battery, and must cut off all power consuming
equipment as soon as the engine is stopped. If an extra
battery has been installed then there must be separate
switches for extra equipment. There should also be a
main switch between the auxiliary battery positive
terminal and the electrical equipment fuse strip. The
main switch for the auxiliary battery must cut off all
power consuming equipment connected to that battery
and be turned off when power is no longer needed. The
engine or drive must not be electrically connected to
other equipment such as the trim plane, bathing steps
etc. The engine and transmission must not be used as
ground points for radio or navigation installations or
other electrical equipment with separate ground cables.
All separate ground cables must have a common
ground point, separated from the engine and transmis-
sion. If shore power is connected, a protective ground
should not be connected to the engine or to any other
ground terminal on the boat. Transformers connected to
shore power must be installed so that the protective
ground on the input side (120/220 V) and the negative
connection on the output side (12 V) are not connected.
For more detailed information on this subject, see the
section
Electrochemical corrosion
in publication
number 7733534
Marine Electrical Systems Part I.
Maintenance and Care
Sacrificial Anodes
If you have a closed cooling system on your engine, a
acrificial anode is attached to a bolt located at the top of
the heat exchanger.
Anodes are slowly eroded away by galvanic action and
require frequent inspection. Additionally, anodes that
are subjected to frequent wetting and drying require
periodic scraping with sandpaper to remove scale and
oxidation to maintain their effectiveness. Do not paint
anodes, as this will destroy their effectiveness.
When you need to purchase new anodes, see your
Volvo Penta dealer. The material composition of Volvo
Penta anodes meets U.S. Military Specification 18001-
H. Some after-market anodes may not meet mil-specs
and are larger in size. Using after-market anodes may
cause cavitation bubbles due to poor fit, which may lead
to propeller erosion. You may order the anodes sepa-
rately, or as part of an accessories kit. (The accessories
kit also includes o-rings, oils, washers, seals, and
bellows.)
Replacing Sacrificial Anodes
Inspect anodes every 14 days, or more frequently if
used in extremely salty water. If an anode is 2/3 its
original size (1/3 eroded), replace it.
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