[Dr. Dave @ Dec 19th 2005 12:55AM]

David,

For a reasonably priced and highly-rated handheld that works well in the car, boat and backcountry, I haven't found a more versatile unit than the Garmin GPSMap 60Cx.

You can get a listing of all the Garmin-compatible maps for the 60cx series using Garmin's MapSource Compatibility tool at: http://www.garmin.com/cartography/mapSource/compatCB.jsp You'll see that among the many maps it's compatible with, the 60cx series uses City Select/City Navigator CDs which are essentially the same database that dedicated in-car systems use.

I believe you can load highway, topo, and marine charts onto your machine all at the same time -- you're only limited by the unit's memory. However, only one map type is displayed, depending where you are. For example, if you're at sea, you'll see the marine chart, on the highway, you'll see the road map. Where there's overlap among more than one map type, the documentation refers to a hierarchy it uses to determine what you'll see. The documentation is vague on exactly what that hierarchy is, but you can read more in the 60CS manual on page 88.

There's a link for the 60CS manual (PDF) as well as a review, description and specs at: http://www.rated4stars.com/html/garmin-gpsmap-60cs_.html

Good luck!

P.S. Don't forget to consider the cost of map CDs when estimating cost. You might also want to consider an available car kit with charger.