I am looking for a low cost, rugged and seaworthy yacht navigation system on a tablet. If you have been there and done it, please tell me:  What tablet do you recommend?  Will it take 12volts DC & if not, how do you power from 12v DC?  How much did it cost?  What software do you recommend?  What do you like about it?  Can it run raster charts based on UKHO paper charts? How do you input GPS and AIS?  How much is the software?