Advanced Marine Electrics and Electronics Troubleshooting A Manual for Boatowners and Marine Technicians

range and requires only 0.5 amp of current, so
even for masthead-mounted sensors, the
weight of wiring aloft will be low.
As with all wind-machine instruments,
especially those with long wire runs up sailboat
masts, you must install cables carefully, using
proper support and strain relief at the mast-
head to ensure acceptable service life. While
Airmar suggests that cable lengths not be
altered, they do provide specific guidelines for
making connections and attaching RFI shield-
ing if you have to remove a cable connector to
facilitate routing through tight openings.
For the average boatowner or marine elec-
trician, troubleshooting this system will focus
on confirming voltage and ground integrity.
The TDR tool (Chapter 3) will be useful to
confirm wiring harness integrity.

Autopilots

Autopilot installation and troubleshooting can
be critical to the safety of your boat and crew.
And depending on your boat, you may need
the combined efforts of an electrical installer
(possibly you), an electronics specialist, and a
marine mechanic.
I say mechanic, because if the boat has
hydraulic steering you may need a mechanic to
mount and interconnect the hydraulic steering
pump that is part of the autopilot system and is
integrated electronically to the autopilot con-
trol box. Depending on the system you choose,
the autopilot pump may replace the existing
hydraulic steering pump. In any case, the
autopilot pump will become the driving force
for the hydraulic ram or actuator at the rudder.
In nonhydraulic steering systems that rely
upon gears or cables (or even direct tiller-to-
rudderstock connections), a mechanical actuator
servo must be linked to the existing steering
system. (You may need a mechanic for this
also, depending upon your skills and/or those
of your electrical technician.)

The illustration highlights several key points:

• The RF ground serves to minimize the
  effects of any EMI with the course
  computer. Equipment vendors’
  instructions for the connection of this
  ground must be followed to the letter.


• The data cable interface harness may be
  split farther away from the course
  computer to provide and receive data
  from NMEA-compatible devices such as
  a GPS, and/or to connect to a proprietary
  network like Raymarine’s SeaTalk or
  Furuno’s NavNet.


• This same harness may also contain
  cabling to feed a system alarm.

installing depth sounders, weather systems, and autopilots 163

Autopilots are an interesting mix of electronic, electrical, and electro-

mechanical components that must be integrated with the boat’s onboard

navigation system to function properly. The system shown is for a boat

with hydraulic steering. On a boat with mechanical steering, the pump in

the illustration would be replaced with an electric servo and a mechani-

cal connection to the steering system.

battery

course computer

to GPS and

alarm system

in-line

power

switch

NEMA interface

(may also be

proprietary)

integral

10 A fuse

integral

ferrite

RF ground plate

autopilot

pump