Some of you may be interested in TeamSurv, a crowd sourcing project to help create better charts.
Participants log depth and position data whilst going about their normal activities, using a simple data logger. They then upload the data to the web site, where tidal and other corrections are applied, and the results can be seen online.
We're just progressing with the next stage of the project, providing downloadable chartlets in areas where we have sufficient data.
Have a look at www.teamsurv.eu
if this sounds of interest.