The Tide Table Handbook
A tide table is a day-by-day list of predicted high and low waters: a time, a height, and the datum the height is measured from.
Each row pairs a clock time with a height. The time marks the predicted moment of high water or low water at a named reference station; the height tells how far the surface is expected to stand above the table's datum at that moment. The vertical difference between a high water and the next low water is the range of that cycle.
Read the time zone printed with the table before anything else. Tables state the standard time of the station's country and whether a daylight-saving shift applies; a one-hour misreading is the most common error made with an otherwise correct table.
On narrow screens, swipe or scroll the plate sideways.
Heights are meaningful only against the datum. Many national tables measure from a chart datum near the lowest astronomical tide, so predictions rarely fall below zero; others use mean lower low water or another average level. Mixing datums between a table and a chart quietly corrupts any depth calculation.
A table is valid at its station, not along the whole coast. Publishers cover intermediate places with secondary-station corrections: printed offsets in minutes and in height, or a ratio, that shift the reference predictions to the nearby location. Each secondary station has its own corrections.
Finally, remember what the table does not contain. Predictions come from astronomy alone. Wind, air pressure, and river flow move real water levels away from the printed values, sometimes by a large margin; official storm and surge warnings exist to cover exactly that gap.
Further reading