http://news.bbc.co.uk/2/shared/spl/hi/pop_ups/08/sci_nat_enl_1208537412/html/1.stm
I wonder what sort of transducers this is using?
Tide gauges have been around for many years, around the coast of the UK there are a number of ‘tide balls’ like this one on Flickr. The wire ball cage goes up and down as the tide ebbs and flows. Many no longer work including this one but you can still see them, this one is on the hill behind Ramsgate Royal Harbour.
Stuart