For the last ten years I've taught a 2-day class on GPS navigation for recreational outdoor users. Students in a typical class include hunters, backpackers, geocachers, and day hikers, along with the occasional park ranger, paramedic, and search-and-rescue volunteer. The class consists of one Monday evening lecture followed by a 4-hour field session the following Saturday. The typical student invariably already owns a GPS receiver but doesn’t know how to use it. Most students don’t have a technical background, so I can’t expect them to know anything about how GPS works.
I am often asked, “how do you decide what things to teach in such a short class?” So I thought I’d describe my typical class here. This simplified description doesn't cover everything, but these are the key points. If the topics sound familiar, you’re probably already a good GPS navigator. If any of this is new to you, it’s time to go brush up on basic GPS skills.
After ten years of classes, I've learned a few things along the way. Early on, I tried to cover too many topics—not only how to use a GPS receiver, but also things like how to read a topo map and how navigate with only map and compass. Over time, though, I’ve learned that too much information can be overwhelming. In recent years, I’ve decided to zero in on those few things a student really needs to know how to do. If anyone wants to learn more, I refer them to my book.
The evening class starts with a quick overview of how GPS works. The main thing students need to know is that a GPS receiver finds its position by picking up signals from satellites orbiting overhead. It needs to be receiving at least 4 satellites to get an accurate position, and things like tree leaves, canyon walls, and tall buildings can block the signals. So ideally, you want your receiver to have a clear view of the sky.
Next I explain the concept of waypoints, which are like the “street addresses” of the GPS system. Students need to know how to store a waypoint and how to retrieve it after it has been stored. After that, they need to learn how to navigate by following a bearing. So at that point, we take a little break from the classroom and head out onto the campus to practice following bearings. This is also where they learn how to use a magnetic compass. We mark the location of the classroom, walk a few minutes away from it, and then use GPS to navigate back. It’s a little challenging for some students, but they’ll get plenty more practice on Saturday.
By that point the students have learned how to get back to a location they have been to before. Next it’s time to learn how to go to locations they haven’t been to before. So we go back to the classroom and learn about latitude and longitude. Besides explaining what it is, students need to understand two additional concepts. The first is that not all latitude-longitude coordinates are the same. If you get coordinates off the Internet, they are often in a format called “degrees-decimal minutes.” If you read them off a topo map, they are in degrees-minutes-seconds. Students need to know how to recognize the two formats and how to set their receivers to accept either of them. (Yes, I know there are other formats like decimal degrees and UTM, but I try not to make things too complicated that first evening.)
The other key concept is that of a “map datum.” This is how geographers fit latitude-longitude onto the imperfect surface of the earth. I try to avoid the technical details and just show students how to figure out the datum their coordinates are referenced to and how to set up their receivers to use it.
At this point it’s time to wrap up the evening class, so I hand out a homework assignment for the Saturday field session: enter into your GPS receiver the coordinates of six waypoints we will navigate to on Saturday.
The Saturday field session takes place out on the Bodega Dunes along the Sonoma Coast. This broad set of grassy sand dunes is an ideal spot for learning cross-country navigation without much chance of tromping through poison oak or really getting lost. The day consists of two parts. In the morning session, we practice navigating as a group to each of the six preprogrammed waypoints. This is their chance to really learn how to follow bearings. They’ll need to know this for the afternoon session, because then they will be on their own in small groups. Without giving away too much of the detail, I’ll just say that in the afternoon, students need to navigate to a new set of waypoints without my help, and the only way the whole class will be successful is if each individual team achieves their own objectives. During our lunch break, I also give a quick course on how to read latitude, longitude, and UTM coordinates from a paper topo map.
By the end of the day Saturday, students invariably feel much more comfortable in their navigation. But like anything, if you don’t keep in practice you’ll quickly forget what you learned. In a recent class, one student had taken the same class two years before. But he hadn’t practiced at all in the interim, and he admitted it was like a whole new adventure to him this time around.
Notes from Steve - Observations from Off the Beaten Path
