Newlyn Tides

[sfh]

have just read info on tides, they related to Newlyn, why?

 

[halcyon]

You have to have some standard, and there is a chap with a tape measure living there, needed to find him something to do.

Brian

 

[peterb]

Heights on Ordnance Survey maps are related to Mean Sea Level. For some reason, this was originally measured at Newlyn. Depths and drying heights on Admiralty charts are related to Chart Datum, usually Lowest Astronomical Tide. So that heights on charts can be related back to Ordnance Survey heights, the difference is quoted on the chart. Since the tidal range often varies across the chart, the difference between the two datums (or should that be data?) varies, so it is usually given at several specified places on the chart.

It's one bit of information that you can safely ignore unless you are trying to use charts and OS maps together.