H. ELECTRICAL AND ELECTRONICS
MAST ELECTRICAL WIRING PROBLEMS AND GROUND FAULT CHECK
Often times the blistering, with white powder residue around fittings on the aluminum mast or
boom is not just a dissimilar metal corrosion problem. More often than not, the root cause can
be traced to a "ground fault", or short, in the electrical system on the mast or on the boat. You
can stop or prevent serious deterioration of the spar system with a simple ohm meter by
performing a ground fault check.
ELECTRICAL GROUNDING SYSTEMS ON A SAILBOAT
There has been a considerable amount of misunder-standing, confusion and incorrect
information over the years regarding the grounding systems on boats, and we attempt to clear
up some of these questions in this article. A great deal of the confusion lies in the use of the
term 'ground' as regards to the electrical systems on a boat. There are actually five separate
electrical systems that have the name 'ground' associated with them. Quite often these systems
have been electrically connected together, either by design or by misunderstanding, and we feel
that they should be separate and distinct systems, each with their own purpose, and their own
These five systems are as follows:
1. The negative 12 volt system from the batteries. This is used to power the 12 volt equipment
on the boat, and is 'grounded' to the engine on most boats.
2. The 'ground' wire on the 110 volt system, usually green in color, and connected to a stake
driven into the ground. This is used to prevent a shock in the event the positive and neutral
wires of the 110 volt system come in contact with each other through a faulty connection.
3. The electrolysis 'ground', which is used to protect dissimilar metals on the boat when used in
4. The radio 'ground', which is used to help the antenna of a radio or loran achieve greater
distance of transmission and reception.
5. The lightning 'ground', which is used to discharge the current from a lightning strike to the
'ground', which in this case, is the water the boat is floating in.
Most of the gudgeons are fiberglass, and the pintals are bronze pins. You should not have any
galvanic action on the pins as they are not in contact with any other metal. The bronze gudgeon
on the W-42 and W-43 should have a zinc attached to it, as the rudder shaft is stainless steel.
The early W-32's with stainless steel pintals and gudgeons should have a zinc on each pintal.
The propeller shaft should always have a zinc collar or a cone over the nut, and it should be
checked twice a year, and replaced if badly pitted. The stainless steel bobstay fitting should
have a zinc attached to it, as we have seen a number of these get pitted out by electrolysis.
a pair of small round zinc plates normally used on metal rudders, and attach through the bottom
hole in the bobstay fitting, or drill an extra hole near the bottom corner of the fitting.
ALTERNATOR DIODE AND FUSE
A diode and fuse are installed in the engine electrical wiring system on the Westsail boats, and
an explanation of their use is given.
WESTSAIL SERVICE MANUAL TOPICS
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