Our biggest design gripe, however, is that the GPS 100 doesn't live up to its claim of IPX7 water-resistance specifications (submersion in three feet of water for 30 minutes), though it floats as promised. After we plunged the device into one foot of water for just 15 minutes, we noticed significant seepage in the battery compartment and condensation inside the display. The unit was still functional following the incident, but we encountered intermittent problems, such as random scrolling through menus and occasional power outages, afterward. We performed the same submersion test on the Cobra GPS 500, and in its case, the test proved fatal. The Cobra GPS 100 is WAAS (Wide Area Augmentation System) enabled for increased accuracy, but it doesn't include any mapping data or internal memory to accept maps and points of interest. However, the device has the features you'd expect in a nonmapping handheld; it can store up to 500 waypoints and create a route using as many as 50 of them. It's also capable of automatic bidirectional tracking. Plus, the intuitive menus let you view average, maximum, and current speed; elevation; trip mileage; and the ETA to your destination. In addition, the GPS 100 features a built-in compass, clock, and altimeter. The device sounds an alarm when the receiver loses satellite reception and when the battery is low. We tested the Cobra GPS 100 under a cloudless sky with a 360-degree view and were sorely disappointed. The device took more than 4 minutes to track four satellites the first time we initialized it; after that, it took at least 1 minute each time we powered on the unit. As with the GPS 500, we had trouble maintaining a 3D (four satellites) fix, both inside a vehicle and while strolling through the streets of Manhattan. Out in the suburbs of Long Island, the unit managed to keep a 2D (three satellites) fix under open skies; in contrast, its sibling was able to hold a 3D fix under the same conditions. It was accurate as far as locating our position, but it faltered in even the most lightly wooded areas.
Battery tests yielded better results. We managed to get just less than 12 hours of continuous use with two AA batteries (not included). That's par for this unit but less than Magellan's SporTrak Color GPS, which has a high-resolution color display.