Galvanic Corrosion; Corrosion Prevention - Four winns 278 VISTA Owner's Manual

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.
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 to prevent
corrosion to your electrical systems and underwater
parts. These anodes will be slowly eroded away by
galvanic action and require periodic inspection. Please
refer to the section on "Anti-Corrosion Anodes" in your
engine manufacturer's manual for additional informa-
tion.
Electrical Systems - Section H Owner's Manual Page