Establishment of a port
Establishment of a port is the technical expression for the time that elapses between the moon's transit across the local meridian at new or full moon at a given place and the time of the next high water at that place. As an example in the UK, the interval may vary from 6 minutes to 11 hours 45 minutes meaning that the time difference of high water between those two places is 21 minutes. At London Bridge it is 1 hour 58 minutes.
The term establishment of the port is identical to the obsolescent term High Water Full and Change Full referring to the full moon and change referring to the new moon. Before the creation of modern tide tables, it was a quick way of predicting the time of local high water. The moon’s passage at the local meridian is about 50 minutes later each day. If it is HWF&C 1 hour 30 minutes and we are three days after the full moon, then the morning high water is 1h 30 + 150 minutes = 0400.