Each year the United States Coast and Geodetic Survey issues four paper-covered books containing information about the rise and fall of the tide at about six thousand places in various parts of the world.
Every ship carries official tide tables.
They also carry a nautical map that includes the level of the water in certain plaes, at lowest tide. With these two maps, one can figure out when low tide is by the tide tables, and how low the tide is by the nautical map, this way they know when the best time to sail into a port is without grounding their boat. On a tide table information is included to help calculate close to exact times the tide will be at a specific hieght. The first official tide table was issued bythe Brittish Admiralty in 1833. The United States began to compile tidal information in 1853.