Chart S/W
DebraI think you should be asking what s/w & chart formats are best for the application you have in mind. The Raytheon onboard chartplotters like the RL70CR that support both radar and GPS usually use the CMap-NT format digitAL charts. Many of the PC nav software programs (e.g., MapTech, The Cap'n, etc.) use digitIZED charts -- there are big differences.Digitized charts are exact replications of the official paper charts, and are geo-registered to a specific horizontal or geoidal datum (e.g., WGS-84) so you can plot/pull exact lat/long positions. As such, they serve the similar purposes of the paper charts -- route planning and more precise navigation & piloting. The digitized format is very computer memory- and processor-intensive, since to capture the fine detail they must be scanned at a very high resolution and then treated with special reduction & compression algorithms.Digital (vector) charts are on-the-fly reconstructions of a horizontal situation. They will show boundaries and will be geo-registered to plot/pull lat/longs. Often they are coupled with a similarly geo-registered information database that provides feature object descriptions (e.g., nav aids, wharfs, hazards, landmarks), and other data (e.g., depth). The digital format is much more computer memory- and processor-efficient, hence their popularity in hand-held devices. Digital charts, because of their ability to be drawn very rapidly, serve the function of a positional reference (chartplotter) very nicely. Since they don't (yet) have the detail and accuracy of the paper charts, you use them for route planning and precise navigation at your peril.Charts in both formats (digitized and digital) suffer from a general lack of regular, affordable updating mechanisms. (For that matter, how many of us are faithfully updating our paper charts from the LNMs?)So, I guess the answer is you must decide which way to go with full understanding of the limitations offered by each technology. It would make more sense to get a handheld GPS as a backup that uses the same chart format as the master on-board chartplotter. Then, they could be shared.Having said all that, I do not have direct experience with Raytheon's s/w. For what its worth, I use the MapTech Chart Navigator software & their digitized charts (with digitized photos & topographic maps) for route planning and downloading GPS waypoints & routes.It works very nicely. I do not bring my laptop PC on-board however because, in general, these laptops are not ruggedized for a marine environment.Hope that helps you some. --Rons/v Lady Jane, Marblehead, MA