Water level offset

Thanks for adding the ability to specify water level offset in settings. Its really useful to be able to change the contour and sounding depth to account into the water level changes. Will definitely use it this weekend t Lake Mead where the water level has dropped a lot due to drought . Water level offset will come in handy there.

Michael-1222 about i-Boating: Marine Charts & Gps, v60.0.0