The basic idea was to use a less power hungry system for chart plotting. My laptop was using a bit over 5 amp/hour by being run thru an inverter. I think this can be cut to 1 or 1 1/2 amp/hour with the Pi. With it being relatively easy to connect sensors to the Pi I've decided to see if I can incorporate an auto pilot into the dashboard. The big question being whether hobby sensors can stand up to life on a sailboat and whether I can develope a low amperage use auto pilot.
News as of Feb. 2017. I have scrapped using the 4 x 20 lcd and have moved up to a 7" touch screen to be cockpit mounted.
Took the gps apart and added the working parts to a circuit board that also sends back barometric pressure and temperature.
Have also completed a 12vdc step down to 5vdc circuit (2 in fact) one to run the Raspberry and the other to run the touch screen. I'm running Ubuntu Mate on the Pi. As the sensors for pressure and temp send analog data and I had to add an ADC I've also included 2 voltage dividers one for battery voltage and one for a future solar panel voltage output. For the time being I have given up on trying to use the magnometer on the 9 DOF chip and will only be using it for heel and pitch of the boat.
photo's of the 12 volt conversion board and gps/barometer/temperature are in the album. I have also found a 12 vdc linear actuator that I'm considering for the auto pilot.