You have to have a computer with either Internet access or a expensive
satellite system. I started using chart plotters
powered by a computer 6 years ago, I put a wireless internet conection so I
could get my almost daily updates. As a result anyplace a can get a
internet signal ( I use a sprint MIFI card ) I'm able to get
marinetraffic.com . The only time
I lose a signal is when I'm to far off shore. Which isn't to offten.