H - 8 STRAY CURRENT CORROSION
A. General
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.
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.
C. Corrosion Prevention
Anti-corrosion anodes are attached to the bottom of
the gimbal housing to prevent corrosion to your stern
drive 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” or “Corrosion and Corrosion
Protection” in your engine manufacturer’s manual for
additional information. The engine manual is included
in the owner’s packet.
Stray current corrosion can be caused by the polarity
of the dockside wiring system of the boat being
reversed from the power source (reversed polarity) or
surrounding boats, an improperly wired battery
installation, other boats that are in close proximity that
have electrical power leakages, or any other source
close to the boat that has electrical power leakage into
the water. Stern drive units are especially vulnerable
to stray current corrosion.
Periodically inspect the drive components and thru-
hull fittings to determine if stray current corrosion
damage exists. If corrosion damage is found, deter-
mine and correct the cause of 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
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-
| Categories | Four Winns Manuals, Four Winns SL-Series Manuals, Outboard Marine Corporation Manuals |
|---|---|
| Tags | Four Winns SL |
| Model Year | 2008 |
| Download File |
|
| Document Type | Owner's Manual |
| Language | English |
| Product Brand | Boats and Cruisers, Four Winns. For support contact your dealer at http://www.fourwinns.com/locate-dealer.aspx |
| Document File Type | |
| Publisher | fourwinns.com |
| Wikipedia's Page | Outboard Marine Corporation |
| Copyright | Attribution Non-commercial |
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