Peter Bennett wrote:
On Mon, 23 Apr 2007 18:36:22 -0400, Keith nuttle
wrote:

Cna the functionallity needed of a GPS for navigating on water be
combined with the functionality need for navigating on roads and high
ways.

I would be nice to have one unit for in the car and on the boat.

A GPS receiver optimized for road use is likely to be pessimized for
marine use :-)

It seems that many of the road-use receivers have features like "road
lock" - as long as the GPS position is within some small range of a
road, the GPS will show you as on the road, rather than where you
actually are. I saw one boater complaining that while he was passing
under a bridge, the (road-aware) GPS suddenly showed him on the bridge
and adjacent road, rather than in the river where he really was.

Land-oriented receivers may also omit the very useful "highway"
display that shows cross-track error and relative bearing-to-waypoint,
as it is of very little use while driving but essential (IMHO) on the
water.}

I use a Map60CS for both, but as my car usage is rare (I can actually find
my way to the Supermarket without it!), I would say buy it with a view to
using it on the water and treat it's use in the car as a bonus.

Dennis.