lasts long and the labels end up in the bilge.
Also label the wires and components on your
diagram. You’ll probably have to list and number these labels off to the side with a corresponding encircled number at the component.
This avoids diagram clutter.
As you trace wires, look carefully for problems, including chafed insulation, hot spots
indicated by browned or blackened insulation,
little bumps in the insulation (indicates corrosion or overheating inside), a burnt insulation
smell, or corroded terminals. Note the problems and fix them before you use the boat
again. If you find an unfamiliar component,
such as a diode, shunt, or transfer-solenoid
switch, ask someone or research the part until
you know what it does. This isn’t just for
accuracy; it will educate you, enabling you to
diagnose problems more easily.
In older boats you might find dead wires,
where an owner has removed something and
disconnected (hopefully) its supply wire at the
panel, but left it behind “just in case.” Should
you take it out, leave a strong nylon messenger string in its place to pull through another
wire later. If you leave the wire, label it at both
ends and be certain it’s dead. Seal each end by
wrapping it with electrical tape and then smear
electrician’s “liquid tape” over the actual tape
to keep moisture out and the tape in place.
VOILÁ! THE FINAL PRODUCT
By the time you get through diagramming the
DC system, you’ll have a good sense of how
you want your wiring diagram to look. This is
a good time to redraw it before starting on the
AC system. AC systems can have more than
one source (shore power, generator, inverter).
If yours is particularly complex, consider hiring an ABYC-certified tech for an hour or two
to walk you through it. Your diagram should
clearly differentiate between AC and DC, or
you can do a separate diagram for each system.
Label which is which and make it obvious
where the two types of current run close to, or
could be confused with, each other. Make at
least one copy to keep off the boat, and store
your onboard diagram in a waterproof container such as a Ziploc bag. If it’s very large, roll
it up in a PVC pipe with two end caps. Glue
one on, and use the other as a removable cap.
Diagramming your electrical system is a
great winter project, and will be invaluable
when you want to install something new.
Tom Neale, a technical writer and liveaboard
cruiser, leads our “Ask The Experts” team.
Cruise through time and explore the rich
history of the Canal System that shaped a nation.
Cruise the Erie Canal