GPS
By Officer Joe Alvarez

GPS, or Global Positioning System, is a satellite-based navigation system developed by the U.S. Department of Defense to provide a consistent, accurate method of simplifying navigation. It provides both commercial and recreational users 24 hour, worldwide navigation coverage. You should not however rely on GPS as your sole method of navigation. Use every method available and compare the results to make sure that you are where you think
you are.

GPS provides accurate position and course information, regardless of the weather or your proximity to land. GPS can help make your boating smarter, safer and more efficient wherever you may travel.

GPS uses orbiting satellite signals to determine your position. The satellites continuously send out signals containing precise position and time information back to earth. The GPS receiver can determine its present position by knowing the position of three or four of these satellites and calculating the various time differences between the transmitted signals. GPS continuously updates your position and provides speed and track information once underway.

Some GPS's have more features than others but all give basically the same information. Most of them have graphic displays and some allow you to see your location on an electronic chart. The electronic chart provides another way of checking your position,
particularly if you are site of land or an object in the water.

Your GPS should accept waypoints (where you want to go) and routes (a series of waypoints leading to your final destination). Upon entering a waypoint the GPS will calculate your current position and at minimum provide:

. A continually updated course to steer to the waypoint.
. A continually updated distance to the waypoint.
. A continually updated speed once you're underway.
. Continuously update the time it will take to get to the waypoint at your current speed.
. Tells you when you are off course and what direction to turn to get back on course.

Various alarms should be available with your GPS such as:

. An alarm that sounds when approaching a waypoint.
. An alarm that sounds when you've come within a preset distance of any of several waypoints, regardless of whether they are your destination.
. An anchor alarm which sounds when you have traveled more than a preset distance from a waypoint.
. An alarm, which sounds when you have exceeded a preset distance from your intended course.

Portable GPS receivers can be purchased for under $200.00 and a fixed mounted receiver for under $300.00. The cost goes up rapidly from there when you get into the ones with electronic charts. It's worth the cost of investing in a receiver to know your position in any
weather, anywhere on earth. Remember, safe boating is smart boating.



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