On Tue, 27 Dec 2005 00:11:51 GMT, Gene Kearns
wrote:

Anybody know of a GPS with this capability?

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Some of the better sailboat systems like Ockam or B&G offer direct
digital readout of current direction and speed. They are calculated
numbers based on observing SOG vs speed through the water, and COG vs
magnetic compass heading. The instrument system resolves all the
vectors and spits out the numbers. It is fairly slick but requires
constant calibration and cleaning of the speed sensors which are
mechanical flow transducers in through hull fittings.

My Furuno Navnet, integrated chart plotter/GPS/RADAR, displays a
heading vector and a separate COG vector on the RADAR screen. It has
an electronic compass sensor to provide heading information. Since it
knows your heading, it can also overlay chart data with the RADAR data
which can sometimes be useful. It needs heading information to rotate
the chart into the proper orientation. I find this function
particularly useful for quickly determining whether a RADAR target is
a NAVAID such as a buoy, or another boat.