Tides are created by the sun and moon exerting a pull on the earth. High tides and low tides are predictable, and each one normally occurs twice daily at approximately six-hour intervals.
Boat operators in coastal waters need to be mindful of the effect of tides. The rise and fall of tides can cause water levels to fluctuate by several feet and also can generate strong currents. Some tidal currents are strong enough that some boats cannot make headway against the current.
As a boat operator, you need knowledge of the tides in your boating area. It is a good idea to learn how to read the tide tables found in many newspapers in coastal areas. Tide schedules also can be found on weather radio channels.