You missed something
I downloaded the SevenC's viewer, but I couldn't import the ENC files from NOAA.The dkLook viewer worked fine.Great resolution once you zoom in. The SF Bay takes a while to load on my system, but if you right click on any feature, a window pops up and tells you everything about what your looking at.(Assuming the rock or bouy is where they say it is.) I think, on a laptop, they would be a very convenient alternative to big paper charts or chartbooks.