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Old 05-31-2001
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Tom Wood is on a distinguished road
Handheld GPS Overview


The use of handheld GPS units is more widespread than most mariners know.
In 1990, Kathy and I became pioneers in electronic navigation by abandoning our ancient SatNav in favor of the newly invented GPS (Global Positioning System). A decade ago, our spanking new Magellan 1000 was a single-channel sequencing receiver only slightly smaller than a carton of cigarettes. It boasted 100 waypoints and one non-reversible route, and it actually offered real-time positions about 16 hours each day, except during the Gulf War when it was shut down unexpectedly. The cost for this unit was a mere $2,500, which in 1990 currency was a lot of moola to impoverished yachties like ourselves.

We've come a long way, baby. Like all electronics in the past decade, the physical size of handheld GPS units has shrunk, more features have been added, reliability has increased, and the cost has been reduced by a factor of ten or more. Until recently, in fact, attempting to review models currently available on the market was almost impossible because they changed so fast that the information was obsolete before it was published. But the pace of change has slowed and model features have stabilized enough to make sense of what each user needs.

Before we begin, I have to admit a large bias will creep into my analysis. For those of us who learned to navigate by DR, tracking on guesswork and thinking that making a landfall within 10 of 15 miles was pretty good, even having an RDF or celestial bearing with an error factor of a few miles was a great improvement. Imagine our delight when LORAN and SatNav came along, even though we only got fixes every few hours or had to translate TDs onto the chart. Now imagine the time we saved at the nav table when the simple GPS unit offered us real-time position 24 hours every day—it was like a vacation for the navigator.


Where portability and functionality meet—the new crop of handheld GPS units.
So what if this position was only good to within 200 feet. Our boat is only 40 feet long, and if we can't navigate the area five boat lengths around us, we don't belong out on the water anyway. So the bias is this—today's emphasis on accuracy to within a few feet is baffling to me. Perhaps it is important in surveying, and I might want absolute accuracy if I was landing a Cessna in the fog, but for boat navigation this kind of accuracy is unnecessary. The great differential debate, and now the clamor for WAAS technology, strikes me as rather absurd. For those who intend to integrate the GPS to the electronic navigation program and the autopilot, in effect asking the boat to navigate herself away from the dock and back again, I ask that they do invest in the greater accuracy and a good insurance policy.

The Basics   At the bottom of the price and features scale, the Magellan 310 is a waterproof little wonder. It has a 12-channel receiver packed into a tiny frame and runs on two AA batteries. Even though the 310 has a NEMA-standard data output, allowing the GPS information to be shared with a plotter, autopilot, or PC, and three graphic navigation screens, it only has one reversible route. The most delicious things about the 310 are its very small size and the price—at under $100, almost every sailor can afford one.

Garmin's answer to the 310 is the eTrex, which is even smaller and lighter and yet packs a few more features. The eTrex is also a 12-channel receiver, but it is differential ready and the one route can take up to 50 waypoints. The trip log and automatic track features are a tad gimmicky, but might be of some use to a few sailors. While I find the eTrex display easier to read than the Magellan 310, the Magellan is more intuitive for me to use for some reason. The eTrex is listed as "water resistant" and the street price on it is $120.


The Garmin 48 offers a rotating antenna that is also detachable.

Garmin also has one intermediate handheld GPS unit that is a step above the basics. The GPS 12 uses four AA batteries and gets a little more life (24 hours) from them. It is both differential and NEMA output capable. The key differences between the eTrex and the GPS 12 is that the latter has the operation buttons on the front of a slightly larger frame and also boasts 20 routes of up to 30 waypoints each. These routes are reversible and have what Garmin calls a TracBack feature. The average price for the GPS 12 is $150.

Databases   The next step up in handheld GPS features is the database, and here Magellan and Garmin lead the way—but in slightly different directions. With a basic GPS, the navigator enters the latitude and longitude of the waypoints, or can save a present location as a waypoint for future use. On the next level, databases of common waypoints are pre-loaded into the memory of the machine, or can be uploaded from optional PC software.

The Garmin GPS 12XL is the same unit as the basic GPS 12 mentioned above, but it has a North American database using graphic waypoint symbols. It also has several other features that make it worth a closer look. First, it is capable of accepting an external antenna, which is useful if the unit will be mounted down below or under a hard dodger. Second, the GPS 12XL has an internal lithium backup battery, which will maintain those 500 waypoints and 20 routes if the batteries go dead. The street price is $200.

"This model has a backup battery, which will maintain those 500 waypoints and 20 routes if the batteries go dead."
Garmin also has a more extensive database built into the GPS 48. This adaptation of the wildly popular old Garmin 45 has the famous rotating and detachable antenna, is waterproof, has a moving map with plotters and graphics, and a greatly enlarged database with North American navaids. Curiously, the 48 also sells at $200, which for my money makes it a better buy than the 12XL.

Finally, Garmin offers the GPS 12CX. This unit has all the features of the 12XL and looks similar except for the location of the operation buttons. The 12CX's claims to fame are that it's submersible (who uses these things underwater?), it has 1,000 waypoints, it runs up to 36 hours on dry-cell batteries, and (drumroll, please) it has a color LCD screen. In all honesty, I thought the color screen was a gimmick, but I find that for older eyes, especially when the navigator is tired in the dead of night, the enhancement of the added contrast makes a large difference in the readability. The 12CX has a street price of $250.

Magellan's answer in the database field includes two handheld units that are rubber-armored and waterproof. The Magellan 315 has an international database of 18,000 cities and, in addition, can accept data from Magellan's optional MapSend CD-ROM. This Magellan MapSend is a software package and CD-ROM containing many thousands of waypoints for marinas, lighthouses, harbors, airports, and more, allowing the user to choose the points wanted for the next cruise. Up to 20,000 waypoints can be uploaded at one time. The 315 has nine graphic displays, NEMA output, and sells for $150.


The database in the Magellan 320 is written expressly for mariners in the Americas.

The Magellan 320 is the same unit as the 315 above, but will have more appeal to US-based sailors as the database is oriented to the cities and major marine navaids of the Americas. Unique to the 320, sunset, sunrise, lunar phases, and current sun and moon positions are listed (where was this feature when we struggling with celestial navigation and an old HP celestial calculator?). The Magellan 320 commonly sells for $160.

Maps    The next step up in handheld GPS technology are maps. By adding a visual depiction of the boat's position on a map showing the coastline, major lighthouses, and navaids, rivers, and other features, even the most navigationally challenged should be able to find their way around. I own a handheld GPS with mapping technology and have to admit that I've nearly run off the road while watching it move down the highway at 70 mph—the things are addictively mesmerizing and probably more dangerous than cell phones when used in cars.

The Magellan Map 330 has a high-resolution display and an eight-megabyte database of all US areas. It features a 2,000-point track recorder, celestial information, odometers, and a lot of other fluff that most sailors won't use. But it does include the Magellan MapSend software and CD-ROM along with the necessary PC data cables so that more data can be uploaded. At a street price of $250, the Map 330 is great in the car.

If you want a Magellan GPS mapping unit for the boat, however, you should look at the Magellan Map 330M, which is the same unit oriented towards a marine environment. The 330M has all of its maps and databases providing navaids and details of the coastline, with a price of about $270.


Magellan's Map 330 with its high resolution display.

Garmin also has two handheld units with built-in mapping capability. The Garmin eMap is mostly auto-oriented with data and maps for both North and South America—it even has exit information on the Interstates with restaurant and motel data. It has an optional data card with downloadable maps for even greater information. The unit is small and light, and sells for $200.

Garmin's big entry in the realm of handheld GPS mapping units is the GPSIII Plus, which has one unique feature. The screen can be displayed in either landscape or portrait orientation, allowing the user to comfortably hold the unit by hand or set it on a horizontal surface. The GPSIII Plus also has the capability of uploading more data from CD-ROM, and has all the other features you would expect of a high-end map unit. It sells for $300.

Plotters    The final frontier in handheld GPS units currently on the market includes the integration of a plotter. At the moment, there is only one to choose from—the Garmin GPSMAP 175. This unit is physically big, with a large LCD display giving grayscale moving maps. While the GPSMAP 175 does have a worldwide base map permanently installed, it also accepts Garmin's G-chart cartridges to drive the plotter feature. The advantage is that the navigator now has better cartography including depth contours, all navaids, and other nautical information. G-charts are also available for inland areas. The price on the GPSMAP 175 is $500 and G-chart cartridges are sold separately at varying prices.

Handheld GPS units have become so inexpensive, so easy to use, and so reliable that there are very few excuses for missing the harbor entrance buoy these days. Even if one unit fails, for $99 and the price of a few AA batteries, every navigator should have a spare GPS on board. While no machine will ever supplant the navigator's responsibility to log and plot his position, the GPS has turned the time-consuming and odious chores of higher mathematics into a few moments of jotting down numbers from a reassuring little LCD screen.


Suggested Reading:

GPS Gets More Accuracy by Jim Sexton

GPS Interfacing by Jim Sexton

A Few GPS Basics by Jim Sexton

 

Buying Guide:  Chartplotters

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