NOAA has now made all US coastal water charts free in BSB format. They
are called NOAA RNC charts and can be downloaded from he
http://nauticalcharts.noaa.gov/mcd/Raster/index.htm

Fugawi has a free demo software (Fugawi Marine ENC), which reads the
charts and can be downloaded he
http://www.fugawi.com/demo/version4.html