It's a really great start. I have looked for an initiative like this one for a long time. I'm a french sailor and were I live marine charts are not free like in America with NOAA. In fact in most countries in the world charts are not free.

Concerning the depth, it's indeed a very important aspect of the chart but in my opinion it's by far the most difficult to obtain with crowdsourcing. The guys at Openseamap seem to have made a piece of hardware just for that purpose (http://www.ak-modul-bus.de/cgi-bin/iboshop.cgi?show1100,5708...).

Keep on the good work guys, we need an open source solution for naval charts. Thanks.