On The Money
Pinpoint your navigational needs by installing a GPS chartplotter.
by Chris Caswell
June 1, 2004
Not long ago, a GPS (Global Positioning System) receiver using satellites for pinpoint
navigation was very expensive, and one with a built-in chartplotter was only for megayachts. Today,
however, navigational accuracy with a GPS/chartplotter combo is available at everyman prices. Even
better, these are very easy to install and set up. With the Wide Area Augmentation System (WAAS),
GPS accuracy has been greatly enhanced, and the chartplotter shows you the position of your boat on
an electronic chart, complete with depths, buoys and all the details of a paper chart. A
GPS/chartplotter combination makes for worry-free navigation in all types of weather.
STEP 1: Magellan's FX324 Map GPS Color Plotter (about $800) with WAAS, 1,000 waypoints and a
claimed accuracy of just one meter (39 inches!) is used in this example. This unit uses MapSend
BlueNav marine charts on memory cards. An internal antenna allows the FX324 to be mounted without
an external antenna on small boats, and the waterproof color receiver is easily removed to prevent
theft. Start by choosing a location that's easily visible from the helm and has access underneath
for running the power cable. You can use the bracket (as shown) for a variety of positions, or you
can flush mount the FX324 into the instrument panel.
STEP 2: The FX324 requires a DC power supply between 10 volts and
36 volts. An inline 2-amp fast-blow fuse (shown) is necessary for protection, and the unit
is protected against reversed current. The blue wire is connected to the negative side of the DC
power source, while the red wire goes to the positive side. These wires are very fine, so be
careful when cutting away the insulation to join the wires. The FX324 also has output wires for
connection to an autopilot, radar or sounder, and it can be linked directly to a PC with an
optional connector.
STEP 3: The internal antenna is ideal for open runabout use, but if you want to mount the
FX324 inside the cabin or under a hardtop, you'll need to install the supplied external antenna.
This should be located in an area free of radio interference and with a view of the full horizon.
The cable should be routed using the shortest possible path, and it should be away from other
electrical cables. The antenna base is tapped to accept a 1-inch-by-14-inch TPI ball joint so it
can be leveled, but in this installation it's flush mounted to the cabin roof. Not shown in this
installation is the sealant used to waterproof the antenna hole.
STEP 4: Connect the power/data cable to the back of the GPS receiver. Then remove the
protective cap over the external antenna socket and attach the antenna cable. Follow the
instructions carefully to initialize your GPS. The FX324 is delivered with a built-in worldwide map
of coastlines, but to fully utilize the GPS/chartplotter function, you should add a SD card with a
local chart on it (available at marine stores). For practice, there's also a Navigation Simulator
that allows you to use all the functions of your Magellan FX324 without being underway.