MJM Yachts 36z Express - Manual (Page 39)

CHAPTER 6
6.6
As a safety precaution, your AC panel is fitted with reverse polarity
indicators. If an AC supply were wired incorrectly, either aboard your boat or shoreside, a
dangerous shock situation could exist. Normally, the reverse polarity lights should not be
illuminated. If they are, disconnect that source of power and alert the appropriate person.
6.7
Metallic fittings, particularly the aluminum
sterndrives, that are exposed to saltwater are
subject to electrolysis and galvanic corrosion. To minimize potential
damage, your boat is fitted with a sacrificial zinc on the transom, on the
drives themselves (2), on the top of the trim tabs and on the bow thruster
if this option is fitted. This transom zinc is connected to the bonding
system of your boat. That zinc and others should be visually inspected at
least monthly or and replaced before 1/2 of the zinc has been eroded.
Pay special attention to its condition, with even more frequent visual
inspection when in new waters and marinas, as environmental
conditions affect the rate of deterioration. If the zinc erodes rapidly,
current meters can be used to assess possible causes and
remedies. The zincs on top of the cavitation plates of the stern
drives can be easily inspected idaily. The forward zinc underneath each
drive (shown at right) most be inspected by a diver.
5 Zincs are seen in this photo of Volvo Drives: Trim Tab (2), Drive (2) and Transom
Zinc (1) . The Yanmar Drives have zincs on the lifter arms as well as under the Drives.
REVERSE POLARITY
ELECTROLYSIS & GALVANIC CORROSION
ELECTRICAL SYSTEM 32