On Fri, 04 Aug 2006 13:14:05 -0400, Chuck Cox
wrote:

I'm not sure what the
chartplotters are doing, but they should be capable of doing a proper
harmonic prediction, including depth. Can anyone tell me about the tide
prediction the chartplotters offer? Are there less expensive electronic
predictors that I missed?

Both my Furuno chart plotter and my PC based Maptech Offshore
Navigator software do tide and current plotting, which show predicted
height/current speed by day and hour for selected points (tide
stations). This is facilitated by the new, free NOAA charts.

There are a number of PC based systems free for the asking, don't know
about the handheld GPS units but I'd suspect they may be getting into
tide prediction also.