The relationship between Chart Datum/LAT and MSS is a vertical offset ‘Z0’.
To reduce your Bathy Data to Chart Datum or LAT:
- Obtain the Z0 value (e.g. from the Admiralty Tide book to the nearest tidal port of your survey area)
- Obtain the MSS value from the Tideinfo.txt File
- Compute the LAT/ Chart Datum value using the following calculation: Raw Depth – MSS Tides - Z0
- Raw depth is 100.00m,
- Tides is low tide @ -0.87m
LAT/Chart Datum = (100.00+0.87-1.50) = 99.37m
Note: This post processing can be carried out using the Tidesinfo.txt file in a spreadsheet application.