GPSNAVX  GPSNavX does support USB devices which transmit NMEA data (i.e. BU-353 USB GPS). Garmin has chosen not to send NMEA data over their USB port. NMEA is the standard which marine instrumentation uses.

While Garmin does send their proprietary data over the USB port it lacks much of the information NMEA contains such as satellite, active waypoint and route information.

GPSNavX does support transfer of waypoints, routes and tracks via the Garmin proprietary data transfer protocol.

All Garmin Marine models do support NMEA, but require an RS-232 connection. So a Keyspan Adapter or Shipmodule Multiplexer is used.  
(Version 4.0)

GPSNAVX  The negative with Offshore Navigator is it leaves very little room for the chart. Furthermore it cost's allot more than GPSNavX ($199 versus $49).

Here is a screenshot..

http://www.maptech.com/water/OffshoreNavigator/images/feature3.gif

And who wants to run VPC on a Mac?  
(Version 2.05)

GPSNAVX  GPSNavX has become a full featured competitive marine navigation application while retaining the simplicity of the Mac.

The price is an amazing $50. You won't find similar software on Windows anywhere near that price.  
(Version 2.05)

GPSNAVX  GPSNavX is agressively improving the application with new features on a weekly basis. As of late (version 1.30) transfering waypoints to and from Garmin and Magellan GPS support has been added. Support for routes and geoTIFF will go in soon.

I tried MacGPSPro and was very disappointed in the poor user interface, its ability to only work with Garmin GPS, and lack of marine chart support. Also no demo version to test out was not very inspiring.

The folks over at GPSy have no plans for an OS X version as it appears their website has gone stale. I agree it's a good application, but it's time to move on from OS-9.

GPSNavX is quickly becoming a very powerful OS X navigation application without becoming bogged down with complex additions that few need.

If there is a feature you want in GPSNavX email gpsnavx@mac.com  
(Version 1.3)