I have a Walkabout Hammerhead Tablet with stylus and it is guaranteed to be able to take a 4 foot fall without any harm done. The advertising even shows a pick-up truck running over it and it still works. I have all the NOAA charts of US waters on it and SeaClear Nav software. It takes my GPS NMEA input also.
Granted it is monochrome and very heavy for a 9 inch tablet, but it works fine.