Thanks, Westward. Yes, I'm a bit cross with Garmin for discontinuing the support on mine (just missed out o a chart chip on eBay last night too!) 3 amps does sound high. I'm using an iPad with Navionics in the cabin, which works very well for planning, but it's too hard to see to be much use to me on deck in sunlight.
Algey, thanks: if you could figure out the iPad, a picture would be great! I really want the plotter to fit on the binnacle, to hide the hole left by the Garmin!