So what exactly should you look for when purchasing a GPS for your canoe or kayak? Since virtually any GPS unit you buy (from the top to the bottom of the line) should be capable of presenting the data mentioned above, here are the basic design features which make one unit preferable to another:

Raised, Well-Spaced Buttons — Make sure the buttons are raised (not recessed) and spaced far enough apart that they can be operated easily, even with neoprene-gloved hands or cold, clumsy fingers. They are also easier to operate "by touch" in the dark, once you become familiar with their layout.

Front-Mounted Buttons — Some GPS units have buttons on the sides, but these buttons can be hard to operate without physically picking up the unit. They are even harder to operate if, keep the unit inside a protective waterproof case. Buttons mounted on the front of the unit can be pressed quickly and easily, with one hand, between paddle strokes, without taking the unit out of its protective waterproof case, making it very convenient.

Mapping Capability — Mapping capability is not absolutely necessary if you're just using the unit for diagnostic purposes, but if you plan to take a few extended trips in unfamiliar areas, a good base map and some reliable mapping software can be amazingly useful and reassuring—especially when you want to quickly check your course in violent conditions that don't permit you to unfold a conventional paper map across your lap. Of course, you'll also need to verify that the unit you purchase offers enough built-in or add-on memory to store detailed map data for your trips.

Configurable Data Fields — Make sure the unit allows you to choose which data fields ("speed," "speed made good," "total mileage," and other such values) are displayed on a particular screen. Paddlers will want to be able to set up their GPS so that all or most of this data can be displayed simultaneously, on a single screen, rather than needing to scroll through, menus or submenus. The less you have to fiddle with buttons, the less often you need to take your hands off your paddle.

Good Battery Life ("Battery Saver" Mode) — Some manufacturers list the approximate battery life for their GPS units; others do not. Search the Internet and read reviews about the units that interest you. The longer the battery life, and the fewer batteries needed to run the unit, the better. Most GPS units require at least two "AA" batteries to run, but a decent unit should allow at least 8 - 10 hours of operation if it includes a "battery saver" mode to reduce battery drain. For the average paddler, that is sufficient to run the unit continuously for at least one full day of paddling, which is good. You don't want to have to change batteries more than once per day on a trip—the less often, the better.

Clear, Well-Sized, Backlit Viewing Screen — The clarity, contrast, and overall size of the screen is important. Buy a unit with a screen that you can read clearly whether sitting still on a calm lake or pitching violently in tossing waves. A screen which measures 2" x 2" (or larger) is adequate. Avoid micro-sized units which force you to squint to read information on their tiny display. Make sure the contrast of the screen is legible in bright, direct sunlight. Make sure the screen can be backlit for nighttime viewing.

There are literally hundreds of "gimmicky" features that you don't need, but a few may surprise you. Here are some of the unnecessary features:

Color Screen — A color screen can be handy for adding a little bit of visual distinction to certain symbols and areas of the map, but this "benefit" is outweighed by the fact that color screens tend to raise the cost of the unit significantly, and also draw more power to shorten battery life. A black-and-white screen works just as well, for less money, with less power drain.

Anchor Alarm — The anchor alarm function is useful to a boat at anchor, to notify the user if the boat starts to drift and drag its anchor during the night. For a paddler, this feature is fairly useless, so unless you also plan to use your GPS on a larger boat, "anchor alarm" is unnecessary.

Electronic Compass — All GPS units include some sort of compass feature. Those with a true "electronic compass" will register your heading even when standing still, while more basic units will need to be in motion in order to register an accurate heading. Neither feature is necessary because your GPS should never replace a reliable, high-quality compass. In fact, you should carry two compasses: a deck-mounted compass and a smaller, pocket-sized "hiker's compass" (to verify directional accuracy in moments of doubt).

Waterproof Construction — Waterproof construction promises some degree of protection from the paddling environment, and most compact GPS units on the market are rated waterproof, but realistically speaking, it is not a "necessary" feature. Why not? Because no matter which GPS unit you purchase—even if it is rated "waterproof"—you should never take the naked unit paddling. Always carry it in a waterproof case. Keep reading to learn why.

Industry waterproofing standards provide very little "real-world" protection for a paddler. To receive a waterproof rating, electronic devices like GPS units and VHF radios need only survive a simple "dunk test" in a calm tank of water. When you subject those same devices to harsher, real-world variables like wave pressure, water turbulence, and extreme temperature changes, however, they often fail. Protect your investment with a good waterproof case—ideally a soft, see-through case like those designed for PDAs or cell phones. You'll be able to operate a GPS unit with raised front-mounted buttons through a soft case, without need to expose it to the elements.

Even inside a waterproof case, there is still one moisture-related enemy to be feared: condensation. When your GPS is sealed inside a waterproof case which is allowed to bake in the sun and dunk in cool water, condensation is inevitable. To combat this problem, tuck one or two little silica packets inside the waterproof case with the GPS. Silica packets are the little white, moisture-absorbing, disposable packets that often come packaged with electronics equipment. Ask a local camera or electronics store to save some for you. The amount of moisture they can absorb is limited, so before you go on a trip, "recharge" the packets with a hair dryer (to dry them out) and then store them in a ziploc bag or waterproof case until you're ready to use them. They'll suck up condensation inside the waterproof case and protect your GPS.

Another enemy to your GPS is extreme heat. Rubber seals and gaskets can deteriorate quickly if left to bake in the sun. When they do, the chances that your unit will fail from moisture intrusion increase exponentially. Never store your GPS inside a hot car or a similar "harsh" environment. It's fine to keep your GPS strapped on the deck of your kayak while you paddle, but when you get to camp, don't let your GPS bake in the sun any longer than necessary. Tuck it in your hull or set it in the shade. If condensation begins to form inside the case, open the case periodically to let it "air out."

In Summary

Casual paddlers can certainly get by without owning a GPS, but there are many compelling reasons to justify the investment. GPS units are more than an aid to navigation; they also provide extremely useful diagnostic information to help you tweak your stroke and your paddling habits. If you're an avid paddler, keep an eye on the market for basic GPS units that fit your budget. Many entry-level units provide all the information a paddler could need. If you're a die-hard multi-day paddler, you may want to spend a little extra on a more advanced unit, but by-and-large, most "top-of-the-line" features are gimmicky and unnecessary.

More GPS Benefits

Paddling Speed And Distance

The average speed of your boat can only be determined if the GPS is on at all times. Otherwise, you must do the calculation yourself. (And they are both only partially correct). If you have the GPS on at all times and you stop for a while, the calculation of average speed would be incorrect. If you paddle in a Z shaped pattern, mark a waypoint at the start of the Z, turn the GPS off, paddle to the end of the Z, mark a waypoint and then calculate the distance between the two waypoints, the GPS will indicate that you paddled 1/2 mile. The GPS does NOT know that you didn't paddle in a straight line. You would have to mark 4 waypoints (each time you turned and then measure the distance between the 4 waypoints and then the GPS would record 1 mile). The GPS only gives the correct distance and speed if the GPS is left on all the time and there is constant paddling or each time the kayak goes into a different direction, each waypoint is marked.

Currents, Tides And Wind

The GPS does not know if the tide, currents or wind is a factor in the paddling. You might be paddling at 3 1/2 knots and maybe there is a tide of 1 knot directly in the direction you are paddling or directly against you. In the first situation, your paddling speed would be 2 1/2 knots and the second example your paddling speed would be 4 1/2 knots. The GPS would give you the correct boat speed, but not your correct paddling stroke speed. If you had 4 miles to paddle and you figured your speed at 4 1/2 knots but the tide is now against you, the calculated arrival time based on the GPS would be inaccurate. You would have calculated maybe about 50 minutes and now it might be 1 hour and 15 minutes due to the tide change. You must be aware of all factors and when the GPS could possibly give incorrect information.

Pre Trip Planning

If you enter the waypoints into the GPS before you set out on a trip (using GPS software or manually entering the waypoints), it becomes a very helpful tool. If you get fogged in you can paddle with your GPS and compass and arrive exactly where you want to go. The GPS is extremely helpful in those situations. If there is a channel that you need to find during low tide, the GPS is very useful for those specially marked waypoints that were marked in your last trip there.

• Marking off hazardous areas to steer clear of when travelling at a rapid pace can be boat-saver and lifesaver.

• If you are going into the backcountry you can navigate miles of logging roads to get to the correct "put-in" site without getting lost.

Marking Waypoints

Coordination With A Map

Easier Than Paper Maps