Reading the table properly
The printed tide table is right and my memory of it is usually wrong, so here is the working version I keep taped inside the shed door.
- Springs and neaps
- Biggest range a day or two after the new and full moon, smallest in between. The table says so; the mud says so louder.
- The two hour rule
- Roughly a twelfth of the range in the first hour, then two, three, three, two, one. Good enough to decide whether to wait.
- Wind on top
- A hard southwesterly adds most of a foot here and holds the ebb back. A northerly does the opposite and does it faster than you expect.
- Pressure
- A centimetre for every millibar below average, near enough. It matters only twice a year, and both times it matters a lot.
None of this replaces the table. It replaces the guess you make when the table is at home and you are standing on the slip wondering whether you have an hour.