AR Nav Supplies Waterproof Pedometer
AR Nav Supplies Waterproof Pedometer ($39.95)
Early this season, my teammate Hani purchased a waterproof pedometer from AR Nav supplies, and it had proved handy in several races. Two months ago I purchased one as well and IÆve had nothing but good luck.
Pedometers are simple devices. A motion-based sensor counts steps and that count is multiplied by a distance the user inputs based on the length of his or her stride. The AR Nav pedometer is a high quality device that comes enclosed in a very effective and perfectly fitting dry bag. The pedometer also comes with a helpful instruction page, prepared by AR Nav Supplies, in addition to the standard pedometer instruction booklet.
Getting set up
The first step in getting up and running with the pedometer is getting it calibrated. It is possible to start with a best guess as to stride length by measuring your steps. Most experienced navigators are already well aware of their stride, so if known, itÆs easy enough to plug that information in. However, itÆs also easy enough to calibrate by simple trial and error.
Started the calibration process by heading out on a hike with my Garmin GPS device and the waterproof pedometer. After the first + mile, it was clear the pedometer was overestimating my distance by around 10 percent, so I changed the stride length setting by reducing it by 10%. The next + mile was close to dead on. By the end of my two hour hike, the pedometer and my GPS were giving almost perfectly aligned results.
But does it work?
Over the next two months I put the device through the ringer. I fully submerged it numerous times, including during an extended whitewater swim. Since I kept it attached to my backpack through several 24 hour training sessions and a multiday race, it was treated with all the abuse I could hand out. The dry bag not only keeps the device dry, it also provides plenty of protection against abrasion and shock.
During this time, I was surprised by the accuracy of the device. There are many ways for a pedometer to fail you. First, pedometer may improperly count steps. Cheap pedometers often over count steps, being confused by vibration or other motion that register as steps. The pedometer included in the AR Nav supplies is fairly effective in distinguishing steps from other motion, and in multiple checks, the pace count was 100% accurate. The only time I was able to identify any pace counting error was when climbing in a 5.4 to 5.6 canyon near Yosemite; here tentative steps and motion did rack up a few false steps. I suspect this wonÆt be an issue in many adventure races.
The other source of errors is the result of users having different stride lengths during different activities. Running and walking will have different stride lengths; steep uphills and downhills will result in different stride lengths than a flat walk. All pedometers will have resulting errors. The good news is that in most condition, whether a fast hike or an AR shuffle, on flat or hilly roads, the measurements were dead on. Only in the most extreme conditions were measurements off. The biggest errors I found were on extremely steep lose ground. However, on the terrain that is most challenging for a pedometer, navigation via contours and features is typically most simple, and the pedometer isnÆt needed. When walking in open, featureless terrain, when distance estimation is critical, the pedometer is gold.
Steep hills and fast runs also were slightly off. However, the errors are predictable, and therefore easy to adjust for. For example, on a steep hill, the device measured around 5% more than my actual distance travelled, so with a minimal amount of mental calculation, it is easy enough to get a good measurement.
When I first heard about the pedometer I dismissed it on many grounds. One fundamental objection I had was that I didnÆt think I needed it. IÆve worked hard to be able to estimate travel times in a variety of situations and rates of travel. So the final test for the pedometer was to see if I could out perform the pedometer by my standard estimation techniques. Bottom line? If I made no type of mental adjustments for the terrain my personal estimations were about the same as the pedometerÆs accuracy. However, once I made the minor mental adjustments for steep terrain, running versus walking, etc., I was easily able to outperform my unaided time/distance estimations.
Bottom line
I am a converted skeptic. The AR Nav waterproof pedometer is a highly effective aid to navigation. When used without any type of mental adjustments, the pedometer produces results that are good enough for most navigation purposes. With minor mental adjustments, the pedometer can take distance estimation to the next level.
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