Chart plotters play a number of different roles in boat navigation. Many are used at the helm where they provide a real-time picture of the boat���s position relative to a chart. Others are primarily used at a chart table for voyage planning and as a means for automatically recording the track of the vessel for use in future voyages. While the majority of chart plotters are dedicated devices using embedded software it is also possible to use a general-purpose computer loaded with specialized software. The latter choice makes it possible to update the plotter software when desired and makes the computer available to support whatever other applications the user may require.

Although the first usable chart plotter programs were written for the Apple Macintosh computer, almost all software written during recent years has been limited to use on Windows PC computers. Owners of Macintosh computers had to run their machines under Virtual PC in order to use them as plotters. Thanks to new chart plotter software written by Richard Ray, a San Francisco Bay area sailor, Mac owners whose computers use the outstanding OS-X operating system can enjoy using what we believe to be the most practical and user friendly chart plotter system on the market. The program is called GPSNavX and can be downloaded from the net at http://www.GPSNavX.com. The software downloads in a minute or two and sells for $49.95 with demo versions and demo charts available without cost.

As with virtually any Mac program installation consists of expanding the compressed program and dragging it onto the Applications folder on the computer���s hard drive. Charts are loaded similarly. (Note to PC users, that is really all there is to it, find a Mac and try it sometime).

As with almost any Mac program the user friendliness of GPSNavX is truly outstanding, in fact the system is so self evident that no instruction manual is needed to guide even the first time user. Plugging a self contained USB connected GPS receiver into the computer or using a Bluetooth wireless GPS completes the initial setup. The system will also work with virtually any GPS with a standard NMEA 0183 output data stream.

Program setup begins with the totally self evident preferences window and can be completed in a minute or less. The desired chart is selected under the File menu and will load in a few seconds. Unlike many Windows based chart plotter programs, very few subordinate menu choices are presented under the top menu bar headings. In fact, there is rarely a need to refer to the top menu once the system is in use.

Plotter operation and management uses the Mac operating system���s WYSIWYG approach. A floating on-screen "Chart Setting" box provides immediate control of chart image zoom, chart movement, measurement tools for distance and bearing between points, mouse click designation of waypoints, relocation of waypoints and annotation of the chart with complete choice of notation color. The chart settings box can be moved to any place on the screen and made transparent or minimized in size to enhance chart visibility. A selection in the chart settings window will cause boundaries of adjacent charts that have been loaded into the computer���s memory to appear on the chart in use, allowing immediate switching to the adjacent chart with a click of the mouse.

GPSNavX uses raster charts, eliminating any need to become familiar with a new and perhaps strange looking chart appearance. Compatible chart sources include Maptech, BSB Electronic Charts, Softchart International / PhotoNavigator, MarinePlanner.com, Nautical Data International and others. In most cases you can buy only the charts needed for your navigation area.

The fact that the plotter software is running on a powerful computer eliminates all limitations on the length of a waypoint���s identification. If you wish you can write a book about each one and have the entire story appear in the waypoint description. A total of 53 waypoint icon choices are available. Route construction is a simple point and click exercise. The "Instruments" menu option enables NMEA 0183 data from the boat���s heading, hull speed, depth, apparent wind angle and apparent wind speed sensors to be shown on the screen. When those inputs are available the "Track" function will record the date, GPS time, vessel position (lat/long), COG, SOG, heading, speed, depth, wind angle and wind speed at a selected interval between 15 seconds and 5 minutes.

Although like almost all standard computers, a Mac���s display screen is not suitable for viewing other than in a controlled, limited illumination environment. However, I have found the Powerbook���s screen fully adequate in many wheelhouse locations and at the chart table of a sailboat. If on deck visibility is mandatory, a remote, sunlight readable display screen can be connected to the computer with a remote, controlling functions through a wireless mouse. Plus, sunlight viewable screens are becoming readily available and less expensive.