Electricity is scarce commodity on the boat. So, You like to conserve it. Modern navigation solutions, based on PC and powerful dedicated chart-plotters can drain Your battery quickly. Modern chart-plotters, like Raymarine E-series and C-series units draw 32 Watts or 2,7 Amps. Powerful Laptop can easily draw more than 50 Watts and drain Your battery in a day.
Luckily there 2 two new computer technologies, available right now, what save energy and provide enough computing power to provide low-energy navigation. Even if You like to use sailboat specific complex polar-data based tacking computing and other computer-intensive sailboat specific stuff.
Atom CPU is new Intel low-power CPU. Designed specially for ultra-portable netbook computers like Dell Mini 12 and Asus Eee PC 1100, having 24-30 Watt hour batteries. Atop draws less energy than Celeron and Core Duo. Whole system (laptop) spends less than 10 Watts.
SSD drives or solid state drives, next HDD or hard drive. SDD has no moving pars. They are chock-proof and spend less electricity than conventional HDD. Price is still quite high, but smaller units cost only 100-200 U$.
Screen size is still a problem with less-powered units. Dell Mini 12 has biggest LCD screen on the market, still only 12″. Barely enough for navigation, but not most comfortable.