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How Long Is High Tide?

Knowing about tides can be very beneficial. No one wants to be stuck on a sandbar. No one wants to go home empty-handed after a day of fishing. No one has to. A little tide knowledge will keep your boat afloat and the fish frying. Just brush up on the highs and lows and the ins and outs so you'll know how long you have to catch that big one or, if worse comes to worse, how long you'll be calling a sandbar "home."

Semidiurnal
- There are three basic tidal patterns: the semidiurnal, mixed semidiurnal and the diurnal. Tidal areas usually have one of these three patterns. The semidiurnal tide has two high tides and two low tides twice a day, each tide being about the same height. Most coastal areas have two low and two high tides.
Mixed Semidiurnal
- The mixed semidiurnal tide is similar to the diurnal tide in that it has two high tides and two low tides, but the mixed semidiurnal tide heights are not the same. So you can have one high tide that is higher than the other occurring in the same day.
Diurnal
- The Gulf of Mexico has only one high tide and one low tide per day. When this pattern occurs it is known as a diurnal tide. In harbors and bays tides can be higher or lower than what is anticipated because of the weather. Storms, wind conditions and cold fronts can affect the tide height. So not only should you check your tide tables when going out on the water, but also the weather forecast.
Facts
- Most coasts have two low tides and two high every lunar day. A lunar day is 24 hours and 50 minutes long. A solar day is 24 hours long. High tides occur 12 hours and 25 minutes apart. It takes 6 hours and 12 1/2 minutes to change from a high tide to a low tide or from low to high. The Bay of Fundy in Nova Scotia has the world's highest tides. High and low tides there have shown a difference of 53 1/2 feet.

Nature