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It must be Clocks Week.  Recently, while scouting eBay for replacement quartz clock movements, I noticed that the Chinese produce a 12-hour 25 minute per revolution version for use as a tide clock for little more than the 12 hour version https://www.ebay.co.uk/itm/334884985332 , so of course, I had to try a couple.   I borrowed a couple of my least favourite cases and made a small (two tides per day) tide clock for Doranne, because she’s only 17ft 6ins long and a larger tide clock for Humber Yawl Club Brough Clubhouse (See photographs)

So, some questions for you experts:

1.     How do they get a 12hr 25 minutes revolution.  I can’t imagine them thumping the quartz crystal, and I can’t imagine them changing the output gearing for such a low volume production.  It ticks, so there’s a stepper motor, but I doubt they’d try and fiddle with that, so that leaves the microchip circuit.  Do they perhaps re draw the printed circuit so it counts more than 32768 oscillations before kicking the stepper motor?

2.    As we can only travel in and out of Brough Haven between two hours before and 90minutes after high water, I felt I was safe using 30-degree sectors for the hours on the clockface.  To be strictly accurate should I have used:

30° x 12 x 60 x 60”/(12 x 60 x 60 + 25 x 60 + 15)” = 30 x 43200/44715 = 29° to the hour?

3.    These approximate devices are most accurate during springs and least accurate during neaps.  The books say they are best when only adjusted at high water springs, but should this be on the day of the full or new Moon or on the day of the highest tide, which for the R. Humber occurs roughly two days after the full or new Moon?

4.    When I tried to be clever and added “Time and tide waits for no man to the clock face” using Google Translate it came out as “Tempus et aestus insidiatur homini”, but when I untranslated that, also using Google Translate it came out as “Time and tide wait for man” missing out the “no”.  Why was that?

5.    Finally, for another gold star, why do you think I accidentally on purpose dropped a spot of white paint on the black clock caps?

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