Hey Phil, I've got one. I use it to draw up routes on the PC that I then save to a user card and load into the Raymarine chartplotter on the boat. I find it useful to look at routes etc, but I still draw them up on the charts once on the boat. Its also handy to print out a chartlet of a harbour/whatever which I then laminate.
A few quirks: the software is a little clunky, but useable. The raymarine plotter I have can only *replace* the routes/waypoints with those on the card, so save your current ones onto the user card first (ie. loading from the user card overwrites the plotter memory). This can be annoying if you've added waypoints on the boat, but forgot to save them off. There are issues with naming waypoints, as the PC may allow longer names than the plotter.
I think the usefulness depends on what you really want to be able to do. It also depends on what plotter you have, as some (eg. Simrad) can't load form user cards, so it gets a lot more complicated.
Wiggo: sure, want me to bring it along on Thursday? You could borrow it and my user card for a couple of weeks.
I have the cetrek auto pilot and plotter and its not very easy to use, screen is too small and also is downstairs, I have installed a decent garmin on the flybridge, but wanted to find an better way of loading the cetrek with routes, don't really want to replace it
According to http://www.c-map.co.uk/pdfs/PC-PlannerNT-Brochure.pdf, the Cetrek supports the user cards. If thats the case, then the PC Planner is a solution that I'd be happy with. If you want to borrow my reader/user card at sompoint to give it a spin, drop me a PM. You'd have to join the queue after Wiggo though /forums/images/graemlins/smile.gif