Final answer:
Years of tidal records are needed to understand partial tides because of complexities like Earth's rotation, land masses, and variable ocean depths, which affect tides and require long-term data to predict patterns.
Step-by-step explanation:
Several years of tidal records are necessary to determine the most significant partial tides because Earth's tides are influenced by numerous complex factors. Complexities such as land masses, oceanic friction, Earth's rotation, variable ocean depths, and wind contribute to tidal variations, making it difficult to predict tides accurately without extended observation. Over time, these records capture the long-term variations and reveal patterns that help in understanding the relative impact of each factor on the tides at a specific location. Furthermore, the gravitational pull from the Sun and Moon, especially during spring and neap tides, causes the height of tides to fluctuate over the course of a month, necessitating comprehensive tidal data to account for these changes.