Setting BeachClock Tide Clocks
The best way to calibrate your tide clock is to consult a local tide table during either a New Moon or a Full Moon, which results in a "spring tide". A spring tide has nothing to do with the spring season. Rather, spring tides occur twice each lunar month* and have the hightest high tides and lowest low tides. Tide clocks are most accurate during spring tides and least accurate during "neap" tides of the moon's quarter phases which have relatively weak tides. Depending on where you are located, the tide clock may have to be reset periodically to adjust for tidal variations.
Link to NOAA Tide Predictions.
*FUN FACT - “Once in a Blue Moon” some years have 13 Full Moons instead of the usual 12 - with one called a Blue Moon. Identifying which one is the Blue Moon is quite the controversy. Read more about Blue Moons at Sky and Telescope.