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I was interested to find out how would a Tide clock behave, so far up the mighty Humber Estuary. I tried to find a source of Tide data that could be "machine read", however I get the impression that the UK Hydrographic Office  does not provide any such data like the wonderful resource in the USA at NOAA, who not only provide tidal data that can be machine read, but also the harmonic constants for each tide station. So I resorted to manually entering the Tide data for a month for Brough, which has to be for last month because the UK Hydrographic Office only provide 6 days into the future it seems. 

I ran my "Best Fit" software on the Official Tide, to see how to set a Tide clock and then to examine how does a Tide Clock behave at Brough. I have attached a text file that has all the data that you may find interesting to examine David. The file also has a debug dump of how the software iterates to find the "best fit" setting time. 

Although there are times in the month that a Tide clock (if set correctly) predicts the Tide to perfectly match the Official Tide, there are other times that are 90 - 100 minutes different to the Official Tide, that I imagine could be very hazardous for a Yawl to use at Brough. Nearly 1/4 of the predictions are over 60 minutes in error. So maybe the best Latin description for your club house Tide Clock should be "Caveat", because the Tide Clock represents whatever the opposite of a NAVAID is called. It is a pity that there is no "machine readable" data for the Brough tide (unless I'm mistaken from way 'Down Under' in the Antipodes) because it would be nice to research the Brough Tide over more than a single month.

Clearly the mighty Humber Estuary distorts the Tide well away from the pure Moon (M2) constituent at different times of the month. 

I hope that the attached file helps David, to understand some of the issues of using a Tide Clock at Brough.

Regards, Geoff Hitchcox, Christchurch, New Zealand.