Properly set, our tide clocks are quite accurate almost anywhere in the world. However, the effects of the sun, as well as local weather conditions can cause the tides to vary, sometimes by as much as 1 1/2 hours during the course of the month. While there are always two high and two low tides per day, in some locations, such as the China Sea and parts of the Gulf of Mexico, the second high and low tides are so small that there appears to be only one high and low tide per day.

Starting Your Clock

Obtain a local tide table and a calendar that shows the days of the full moon, new moon, etc. Many newspapers publish this information, often near the weather report. On the day of a full moon, insert your battery precisely at the time of high tide according to your local tide tables. If your Tide Clock is set correctly on the day of the full moon, it will display the minimum error throughout the entire month. Usually the discrepancy will be less than 30 minutes and therefore unnoticeable. Typically, only four or five days each month will have a difference as great as an hour.