How Chart Datum is calculated - Hydrographic Tidal Observatory at Newlyn

Great video from Rick Stein, about the the history of the Hydrographic Tidal Observatory at Newlyn Cornwall…

This tidal observatory was built is 1915 to calculate the rise and fall of our tides, it took 5 years to calculate the the mean sea level (height of an object above the sea level ie hill, church or lighthouse) and record the lowest astronomical tide known as Chart Datum which are the numbers located on an Admiralty Chart as the shallowest depth of water.

This station is still on operation today and it’s more important than even as it’s records the effects of global warming, which has increased the depth of water over the years.

Admiralty charts are regularly updated including any change depth of water natural or made made (dredging), buoyage, hazards etc.

You simply add the depth of water for from the tide tables for the pacific area of operation to these figures to get the true depth at High or Low water.

For mid tides depth calculations, you will require a tidal curve for this area and add in the data and times, from which you can get a the depth of water at a pacific time ie slack water for your intended dive site. (See over videos).

This makes great revision for anyone taking the BSAC Diver Coxswain Assessment or BSAC National Instructor award…

For further information about our courses simply follow link https://jurassicaquasports.co.uk/bsac...