GPS:

A Solution and a Problem

Revised by BoatUS editors in April 2012

The GPS (Global Positioning System) has become a fundamental part of the lives of most people today.  But a few years ago it was a star wars type of technology useful for military and navigation purposes. Now probably the vast majority of cell phones have onboard GPS.  This means that most people use them and know about them and the old issues of familiarization of boaters with the concept are just that: old issues.

Today you can have a simple handheld GPS that tells you where you are and directs you to a point, or units that perform at many levels above that, including elaborate chart plotting GPS units that show you where you are on a very accurate multi layered electronically reproduced charts and tell your auto pilot what courses changes to make and where in order to get you to a chosen destination. GPS technology is also integral to the better rescue beacons because with activation and proper use it can tell a rescuer where you are. The GPS has made boating much easier and much safer. So what’s the problem?

The problem is the tendency of some to rely too heavily on the GPS and all the great things that can come of it.

First, while GPS technology, now with certain enhancements, can pin point your location very accurately, it isn’t always exactly right. There are many areas in creeks, rivers and along the east coast ICW (to mention but a few examples) where you can look at your chart plotter and see that it has your boat cruising through dry ground or marshland.  This can be caused by a combination of the GPS and the cartography utilized by the chart plotter, or either one.  Often on a boat “close” isn’t close enough. This is particularly true, for example, where you must thread your way through shifting shoals or rock-lined narrow tortuously twisting inlets as in, for example, the Bahamas.  So the skipper using the GPS must also use traditional seamanship skills of good navigation.

Second, even the best of electronics break. If your GPS and/or GPS chart plotter stops working and you don’t have your position marked on a paper chart, you may be very much out of luck.  But it’s easy enough to carry two, one might think. Think again.

In the recent past the military exercised what was called “Selective Availability.” Without getting into scientific and military speak, suffice it to say they would deliberately compromise the ability of the civilian population to get the most accurate data from the system. This was done in the interests of national security.  More recently this has stopped, but if the need arises, the military can do it again.  If GPS is the only thing telling you where you are, where you’re going and how you’re going to get there, you’re probably going to soon be wishing you were skippering a condo in the mountains.

Also, sometimes a satellite upon which the system relies is taken off line for “maintenance.” When this occurs there are areas where GPS service is impaired, sometimes significantly.  While this occurrence is usually announced in USCG Notices to Mariners, we don’t always hear these and there may be times when it doesn’t get announced.

So to the extent that this incredibly helpful technology has lulled some of us into laxness or ignorance of traditional skills and techniques of seamanship, there’s an ever increasing and very serious problem.  But for those who use it as it should be used, it’s an amazing boon.