We use a 400 watt inverter (30 to 40 dollars) along with a six outlet type surge suppresor for powering our wireless modem, laptops, camera battery chargers and cell phone chargers. We have a cigarette lighter outlet on the front of the rear dinette seat for the inverter to plug into. This allows for all this stuff to be up and running while we are cruising. This way we run coastal explorer software on the laptop while putting our boat on course with the hand held auto pilot. Plus at night I can run a cpap machine off the same power strip inverter combo. We can have our anchor light on and have all this running on the house battery and still not have to switch to the second battery to start the motor in the am. We use the same inverter and power strip setup in the truck for internet access using a USB type cell card in conjunction with a wireless modem to get info we need while speeding down the highway.
D.D