Chart updates is why I'd like to use USGS charts.
Keep in mind that chart updates may not be even necessary where you boat. Here in Maine they pretty much mean squat where the currents & tides don't move sand around and change water depths like they may in the intra-coastal. Even so NOAA charting rarely updates these sand-bar movements on their RNC / raster charts. What is on the floor of the ocean here has not changed in hundreds of years unless there is a wreck. Heck on my work skiff I am running a Garmin chart from the mid 2000's. No need for anything more accurate as the hunks of granite have not moved since the days of plate tectonics.
With CHIRP, update accuracy and speed are unprecedented, and our government already provided them free.
CHIRP is a transducer technology ideally suited for fishermen and is related to depth and fish finding. It really has no bearing on a sailboat moving at slow speed not fishing. You'll pay more for a CHIRP enabled plotter, but it is not necessary. Some plotters can now upload your sonar info, and other boaters sonar info,
crowd sourced data, to create more accurate
vector charts (ENC's). I don't know of a single free government
raster chart that has been updated via crowd sourced sonar data.
Active Captain doesn't seem to appear on any dedicated marine line.
Ken
Active Captain is not available on any plotter that I am aware of, except for Furuno $$$$$, but is avaible for your phone or tablet.
Garmin's free standard
g2 vector charting looks the most like a NOAA chart, except it is a true digital vector chart.
Out of all my customers I have only one who prefers a
raster chart (RNC) over a vector because he is so vision impaired that he likes to zoom in on soundings and as he zooms the sounding gets larger. It gets larger because he is simply zooming in on an "image" of a chart, not a digitized chart.
Digitizing charts is expensive thus they are not free. A vector chart (ENC) is a digitally made chart that allows zooming without having to load an additional chart. A raster chart is an "image" or "picture" of a NOAA chart so when you zoom in it just gets more grainy. If you are enter a harbor for example and you zoom in on a loaded raster you will only ever get that scale and would need to load the next scale NOAA chart for the harbor. With a vector chart the zoom is automatically loading, as you zoom, because it is a digitized chart not just a scanned image.
There are no
plotter manufacturers, who offer the direct NOAA
ENC viewing capability. For that matter I don't know of any that allow a direct downloaded NOAA raster chart either. They all
adapt the NOAA charts to work with their software. Raymarine has units that can display the free "Lighthouse" charts (based on NOAA charts) but IMHO they are horrible, stripped down versions, not the same as a direct NOAA download. If you wanted RNC for a Raymarine you'd need to download their Lighthouse RNC charts in order to work with the Lighthouse II software.
Buy an inexpensive plotter, with the free charts, and go have fun. Or get a computer and remote display.