Does the accuracy of a GPS unit depend on its features or will even the cheaper handheld units provide equally accurate information?
Mark Sloan responds:
With selective availability now turned off, the accuracy of all units has improved considerably and you'll find very little difference in accuracy among the makes and models. The primary difference between GPSs are the individual features of each unit. Your personal requirements will determine which unit is best for you. I feel, however, that those units with external antennas provide better signal reception from the satellites than units with built-in antennas. Reduced reception is typically due to interference caused by using the unit below-decks, under a bimini, or by other obstructions that tend to block the signals.
Many units, even some of the less expensive models are "Differential Ready," meaning that an optional differential beacon receiver can be plugged in. If the highest consistent level of accuracy is desired, a unit that is differential ready should be considered. The differential beacon receiver can be purchased separately at a later time to enhance accuracy.