The Northstar 951XD boasts a 12-channel GPS receiver and dual-channel differential receiver.

The Northstar 951XD boasts a 12-channel GPS receiver and dual-channel differential receiver.



Shopping for a GPS (Global Positioning System) these days is a lot like buying a car. A Hyundai works about as well as a Mercedes, if you only need to get across town.

With navigation electronics evolving even faster than computers, yesterday's expensive high-technology often transforms overnight into competitively priced consumer products. Still, you don't get something for nothing.

Hand-held, bare-bones GPS receivers not noted for speed or accuracy start at around $100. On the other end of the spectrum (the $10,000 end, to be exact) are the truly state-of-the-art PC processor-based GPS systems, boasting chart plotters, incredibly detailed raster charts, bright color displays, nearly instantaneous 12-channel GPS receivers, dual-channel differential receivers and 10-foot accuracy.

Most dedicated platform (non-PC-based) units are considerably less expensive, but still offer many high-end features. Northstar's premium quality 952XD differential GPS/chart plotter is a perfect example.

While its $3,895 retail price (10- to 15-percent discounts are common) is somewhat higher than discount chain store offerings, its pedigree is impeccable. Northstar is well known in aircraft avionics, and its navigators were voted "Best in Performance and Reliability" by NMEA 19 years in a row.

The 952XD is the color-screen version of Northstar's best-selling 951XD GPS/chart plotter, which is a huge improvement over the monochrome display. Its 12-dedicated-channel GPS receiver and dual-channel differential receiver automatically search and lock onto the best station, providing a typical fix accuracy within 10 feet and speed within 0.1 knot.

This level of accuracy is 10 times better than the 100-foot fix accuracy of good GPS systems without differential receivers. Spending a few more dollars up front also buys you speed. The 952XD is considerably faster (up to 20 times faster) and more accurate than other less expensive GPS receivers using one or two channels that switch between satellites.

Size matters, too, especially when you are trying to read the display and push buttons in a rolling boat. The 952XD is just large enough to provide the real estate needed for easily used buttons and a modest size display, without hogging the entire instrument panel or being too large to mount overhead.

The compact 7-inch diameter by 3-inch high combination GPS/differential antenna simplifies installation, eliminates electrical interference and reduces complexity.Naturally, the entire unit is waterproof and includes user-configurable shared data outputs for other navigation instruments and autopilots.

A satisfyingly quick, smooth and intuitive chartplotter complements the 952XD's impressive GPS performance. Display brightness and contrast are easy to change and readable in bright sun or in shade. Most functions require just a touch, rather than punching in coordinates.

Unfortunately, some level of familiarity is required with any menu system; Northstar's is good, and only occasionally inscrutable. Compact and readily available vector graphic Navionics Nav Chart cartridges provide "layers" of data that can be easily customized using on-screen menu selections.

Compared with most chart plotters, this one is a rocket, never forcing you to wait when you zoom or rapidly pan across the chart. The "Quik" feature makes routes and plotting waypoints easy by eliminating keying in coordinates.

All things considered, the 952's plotting and GPS functions work well and are easy to learn. The system takes perhaps 20 minutes to learn if you have no previous GPS/plotter experience. That's high praise for high-end navigation gear.

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