Here is the Navionics website:
Navionics - We start where the road ends | Navionics
Click on the map on the first page and scroll around as well as zoom with the mouse scroll wheel to the area you are interested in. If the the 1' contours are there, they will have them. Yes you do get online updates quite often. There is a really cool feature where local folks put their waypoints in as well for certain features, so it's a good idea to update often. What's also nice is when you get the card and update for the first time, it will download a version on your computer. That way you can look around and put your waypoints in, routes, etc. Then just download onto a 2 GB card and into the unit.