Where is the datum that tide height is measured from?
My answer is only applicable for the UK, as other countries will, I am sure, have their own defined benchmark “0” but you are correct to say Zero Ordnance Datum is measured from a mark in Newlyn see http://benchmarks.ordnancesurvey.co.uk/p… How and why Newlyn – I have no idea, Probably just historic, just as the “0” meridian is defined as a line throug Grenwich Ah, ther we go, a little googling finds http://www.newlyn.info/content/view/117/… and http://www.newlyn.info/content/view/127/ these give some background information on the history of the tidal observatory at Newlyn and how it was chosen above all others. Knew Proudman Oceanographic Laboratory would have something. A conversion chart for Newlyn Datum to other major UK coastal
