Content

Each chart currently consists of three data sets:

• the processed data as spot depths on the grid scale(s) used for processing the data
• a shaded contour chart of the area, produced from the spot depth data
• a data density plot showing the number of data points in each grid cell, and thereby giving an indication of the accuracy and reliability of the data

Horizontal positions are in decimal degrees; the horizontal datum is WGS84. Depths are in meters below chart datum. Note that all depths shown are mean depths, unlike nautical charts which use a "shoal bias" to show the shallowest waters in an area. The coastline is approximate and only to aid orientation.

As well as downloading the charts, you can also view them online.

Formats

From the web site, files are available as PDF files for simple viewing online and printing off. We can also provide ESRI Shape and other GIS file formats, and .CSV files of spot depths. We are also working on code to produce data in S-57 and other chart formats. The PDF files are probably best printed off at A3 size, as you may find A4 too taxing on your printer resolution or your eyesight. The .CSV files hold the processed points, with position as latitude and longitude (and in some cases as a grid such as UTM), and depths as depths below the chart datum. These can be read in by most applications, and are particularly suited if you want to do your own processing of the data.

Usage

 Please note that by viewing or downloading any chart files, you are agreeing to the following terms and conditions:

• You accept that these charts are produced automatically from crowd sourced data, and may contain inaccurate or erroneous data. As such, the charts are made available with no warranty, and are not to be used for navigation or for any other critical purpose. It is your responsibility to assess whether they are adequate to meet your needs.
• The charts are for your personal use only. You may not distribute, reproduce or publish the charts or the data therein, whether for commercial purposes or not, without prior written permission. If you know someone who would like to use the charts, please ask them to download the data from the web site for themselves.

Coming Next

 We are currently finishing off fully automating the chart production process, and also producing a single, interactive display for both track and chart data. This means that chart production will always be  fully up to date - until now we have had to rely on doing this manually whenever someone had time, and as a result chart updates have lagged far behind. This will then be followed by having the charts available in a number of formats for both mariners and GIS users. You can see the new viewer as it develops here.