How many years of study are typically required to determine the mean high tide?

The determination of mean high tide involves complex scientific measurements and observations over time due to the natural variability of tidal patterns influenced by factors such as the moon's position, weather conditions, and geographic features. A commonly accepted period for accurately calculating mean high tide is 19 years, which aligns with the lunar cycle and provides a comprehensive dataset that accounts for various predictable changes in tidal behavior.

This 19-year timeframe allows surveyors and oceanographers to gather sufficient data to analyze trends and establish a reliable average that reflects the long-term patterns of tidal fluctuations in a given area. This period helps ensure that the calculation is representative, making the results more useful for legal, environmental, and construction purposes. Other timeframes such as 10, 15, or 25 years may not cover enough cycles or might introduce too much variability in the data, thus making 19 years the most scientifically sound choice for determining mean high tide.