With the new detailed, full-color electronic charts and computer software to display and manage them, sailors can now bring the highest quality navigation information on board. And with more powerful, less expensive computers, they can own a navigation system that costs less than a single-function chart plotter. Once set up for your needs, the system can also handle an array of functions, from weather fax to communications, not to mention business and recreational uses while on board.
All computer charting and navigation programs work somewhat similarly. The key differences are on how the intricacies of the various navigation techniques, chart updates, nav logs, route planning and different types of electronic charts are handled, as well as the use and display of tide data and current vectors.
First, the software is transferred onto the hard disk of your desktop or notebook computer. The computers serial (Com) port is then connected to a GPS receiver via a supplied cable.
Electronic charts available on both floppy and CDs can also be loaded onto the computer's hard drive, or the CD-ROM can be accessed directly. When you start the navigation program, it receives the current position from the GPS, displays the appropriate chart for that position and marks your position on the chart with a ship's icon. As the sailboat moves, position changes from the GPS are updated on the chart and you see your vessel's location in real time.
Typically, information such as the vessels heading and speed are also displayed and range and bearings can easily be made using the "rubber band" attached to the vessel's icon. Courses and routes can be entered by pointing and clicking on the chart, or entered manually by typing in coordinates, and then stored for future use.
Several companies offer preplanned coastal routes that can be modified for your departure date and time, boat speed and stops along the way. These routes are displayed on the chart, and the coordinates can be uploaded into the GPS and used via the autopilot for automatic steering.
The great thing about route planning on a computer is the ease and speed of the initial planning and any subsequent changes. For example, if you are heading down the Intracoastal Waterway on a preplanned route, you can enter the time you need to be at a waypoint to make a bridge opening or marina dock time. With a click of the mouse, you can calculate the required departure time.
Routes can be planned on the computer's NOAA raster charts and uploaded to your GPS to be used with its vector charts. This allows the computer to remain safely below at the nav station and the waterproof GPS plotter is used in the cockpit for steering. Granted this is a redundant and expensive navigational system, but using redundant navigation aids is the safest way to go to sea. Besides, if you already own a notebook computer and GPS plotter, the only additional expense is the second set of electronic charts and the navigation software.
The other great benefit of using electronic charts and a computerized navigation program is the wealth of information and data that is immediately available to you. All the information from the coastal pilots, light lists and cruising guides is now available on either the chart CDs or on separate floppies. Some companies include this information on their navigation software CD. With a single click of the mouse you can see this information displayed on the screen.
Electronic charting software is a wonderful navigational aid, but remember it is designed to supplement navigation information from other sources and should not be used as a sole source for navigation. As errors and malfunctions are possible with any electronic system or computer, you must continue to use traditional navigational methods on your paper charts.
Which program would best suit your needs? See my article "Computer Navigation Software That Best Meets Your Needs"
- - J.S.