You can get the navionics app for android as well. You can get a Nexus 7 Tablet for $240 (which has built in gps) buy the app for like $20 and then get a dash mount to put it in your boat and still be under $300. Not a bad price for a 7" gps plotter. Plus you can keep all your music ect... on it. Im sure you can even find a waterproof case for it.