Mike writes: << The greatest advantages of vector charts based on S-57 and DNC is that they are built algorithmically from the underlying database which is used to generate the existing charts. note that the entire DNC chart database is availble for downloading. these are the charts for ECDIS-N - the USN's version of ECDIS. they do not rely on some third party transcribing paper charts. these are the real item. ............what you are seeing now in the market is people scrambling to invent ways to remain relevant - add aerial and satellite photos, add bathy data, add this, add that, but at the end of the day, that's all chrome on the bumper. the real nav data is readily available and the days of cribbing off paper (or film) charts plotted from databases are over. the DNC files are built algorithmically and they are updated electronically. there's no reason you can't have an electronic chart that doesn't reflect the latest changes and Notice to Mariners, and you don't need the resellers to get it. that's why the vendors are frantically troweling on new "features" trying to salvage a business model that's got a leak below the water line.>> ============ I certainly agree that the current chart "repackaging" model has a leak below the waterline. A navigational program that would work directly with the database, doing the heavy lifting of position plotting on a recreated S-57 type chart display, would eliminate the middlemen. The problem is that portions of the the underlying database may be incorrect or outdated and any errors there will be reflected in both paper and electronics charts. In my cruising area, navigationally relevant features which have changed as far back as 20 years ago have yet to be altered on the charts. And my area is geographically stable. In faster changing locations along the Atlantic Coasts and the ICW, chart makers have long abandoned keeping up with current conditions. By the time an area is resurveyed and the data base updated, conditions have changed again. Local knowledge is still needed. Now for a question about satellite imaging. Google offers satellite images of any location, referenced to latitude and longitude. I took a careful reading of my front porch on my Garmin 76 GPS, then entered the lat/long data into Google. An image came up of the general area of my house but the location pointer pointed to a spot several hundred yards away. This is far greater than the error currently estimated for GPS. Why the discrepancy? Do Google satellite images and GPS refer to different datums? I don't intend to navigate using satellite images but I'll bet mapmakers use these images in drawing charts. Inquiring minds want to know. Larry Z