I have done just what you are trying to do, except I used a freeware program called Seaclear. To download Seaclear, go to www.sping.com, then click on "Seaclear". To obtain charts, go to www.nauticalcharts.noaa.gov

It takes a little work to use these programs, as you have to calibrate the charts using the Seaclear software. Plan on spending a couple nights at it. Once you get the hang of it you realize that you can make your own charts using a digital camera. Just take a picture of an existing chart, get it into your machine as a WINDOWS bitmap (.BMP) image, then calibrate the chart (for Lat/Long) using SeaClear. One time I photographed a regular road map and then drove around and saw the "dot" move up and down Interstate 5.