GPS Has Changed How We Navigate…Here’s How It Works

May 4, 2012

By now, you’ve no doubt come in contact with Global Positioning System (GPS) in one form or another. After all, if you’ve got a smartphone, you’ve probably already got an app for that. But what is GPS? And, more importantly, how has it changed the way we approach boating?

From the days when ancient mariners practiced coastal “landmark” navigation, through the complicated process of “dead reckoning” using a compass, ship’s speed and the hope you’ll get close, it wasn’t until we looked to the sky that our position was something more than a guess. While celestial navigation wasn’t exactly foolproof (not much help during the day or on cloudy evenings), a clear night sky and a sextant were definitely a huge step forward.

The technology we know today as GPS began as land-based radio signaling (some are still used today) and position was calculated by determining how far the boat is away from a known source signal. Now, of course, we use primarily satellite-based, high-frequency signaling and new receivers that are easy-to-use and extremely accurate.  

So now, no matter where you are in the world (assuming you can get a signal) your course and position data is right in front of you and usually right on the money. This makes it easy and convenient to calculate your proximity to land, other vessels and approaching weather. For recreational boaters, this has provided a new level of comfort and security when underway.

It’s amazing, really. There are satellites orbiting the Earth, constantly transmitting signals that contain position and time information. All your GPS has to do is grab a few of those signals and make an quick calculation to determine the differences between those signals (the same way old-school mariners “triangulate” their position using a known fixed point like a lighthouse) and you’ve got yourself a spot on the map you can trust. And because the information is continuously updated, you can see an accurate heading, along with your speed and, sometimes most importantly, where you’ve been.

Of course, all GPS systems work a little differently, and all have their own bells and whistles, but they all essentially work the same way and provide the same basic information. Generally, you’ll have some sort of graphic display to see your location, and many, especially a GPS that’s designed for boaters, will offer a charting feature to put your location in context with your surroundings. They come in different shapes and sizes from handheld to fixed-mount but, again, the basic functionality is the same.

One feature you want to make sure you master before hitting the water is the Waypoint function. This can be as basic as marking your point of departure (usually “Home”) and giving your self a virtual crumb trail back to port. Or you can program in a few stops you want to make during the day, which helps you determine when you’ll arrive at, say, a dockside restaurant for lunch. Fisherman can also mark their favorite “honey holes” so they’re easy to find the next time out.

While GPS systems won’t completely eliminate the need for more traditional charts (they’re not much good if your electrical system fails), they have made it easier for boaters to get more adventurous and confident out on the water.