What is the tide clock?

A tide clock is a specially designed clock based on the apparent motion of the moon around the earth.

Many of the tides along the coastline are combined sun and moon tides, but the moon still accounts for the majority (67%). 

The tide clock operates according to the time interval between lunar tidal highs, an average of 12 hours and 24 minutes. The bottom of the clock is marked as low tide and the top is marked as high tide. The left side of the clock face indicates the number of hours from the high tide, counting down from 5 hours to 1 hour. 

There is a hand on the clock face that indicates how long until the maximum tide (lunar tide) is on the left side of the clock. The right side of the clock face indicates the time from the low tide, which is also a countdown from 5 hours to 1 hour, and the indicated value is also the low tide time of the lunar tide. Some tide clocks have hands that count down high or low tide, such as when high tide or low tide is over an hour. And when the pointer reaches the halfway of the tide, the calculation of time will be one hour before the high tide or low tide . 

The tides have a fixed advance or lag phenomenon in different places, so the tide clocks are set according to the local lunar tide time.