GPS systems use a constellation of Earth-orbiting satellites to determine and plot a location. This type of technology was once only used by the military but has been opened up to the private sector. A GPS receiver can tell you the latitude, longitude and altitude of your current position. To make use of a GPS system even easier, most receivers can download this data into a map format. GPS systems can also trace your path as you move; that's why they are now being used by sailors. If you run into trouble sailing and need to call for help, a GPS system can help rescuers get to you.

But as a sailor, you should be aware that GPS systems can fail. For this reason, some experienced sailors believe that when sailing you should not rely solely on sailing GPS technology. Sailors have been using nautical charts and other sail navigation methods to determine their course and watch out for water hazards for many years. Nautical charts are one of the most fundamental tools available for marine navigation and portray many features of the marine environment not determined by a GPS system such as depth of water, configuration of the sea bottom, rise and fall of the tides, and locations of man-made aids in navigation. If you are going to be an expert sailor, you should know how to use GPS technology effectively along with other traditional sailing methods.