Tides are frequently in the form of coastal Kelvin waves of semi-diurnal frequency. The tides are forced by the periodic changes in the gravitational attraction of the moon and the sun. These waves propagate along the boundaries of an ocean basin and cause sea level fluctuations at coastal stations.
The M2 tide caused by the Moon has a wave period of 12.42 hours, and the S2 tide caused by the Sun has a wave period of 12.00 hours. Tidal Bulge moves like a wave, that is turned by rotation of the Earth. Wave turns right in the Northern Hemisphere and left in the Southern Hemisphere. When it encounters the coastline, it becomes a coastally-trapped Kelvin Wave. Co-tidal lines connect points that experience high tide at the same time, and Co-range circles connect points of the same tidal range.
1The Oceans, Their Physics, Chemistry, and General Biology. New York: Prentice-Hall, 1942.
https://publishing.cdlib.org/ucpressebooks/view?docId=kt167nb66r;chunk.id=d3_4_ch14;doc.view=print
2Bowden, K. F. 1984. Physical oceanography of coastal waters. Ellis Horwood Ser. Mar. Sci. John Wiley & Sons.