What datum are boating safety charts on?
All current boating safety charts are published on the horizontal datum of GDA94 which is compatible with WGS84 datum. Your GPS or DGPS receiver should be set to WGS84 (or GDA94 if available) and you will be able to plot DGPS or GPS positions directly onto the boating safety chart. Boating safety charts earlier than 2000 are on AGD84 datum and you must set your GPS or DGPS receiver to this datum to plot directly onto these older charts or you must apply a correction. The vertical datum (for soundings) of all boating safety charts is Lowest Astronomical Tide (or LAT). Older charts are on Low Water Datum (LWD). The horizontal and vertical datum of all current charts can be found in the title area on each chart.
