Let’s now use the tide table to calculate the tide for a standard port. But first, what is a standard port? In the tide table we distinguish between standard ports and secondary ports. A standard port is a port for which the times and heights of high and low water are predicted for every day of the year. A secondary port is a port that has an assigned standard port. The reason for the use of secondary ports is that it is impossible to list the times of high and low of each port in the world. The tidal curves of the secondary port and the assigned standard port are assumed to be the same.