A tide chart looks like it is telling you when the water will be moving. It is not. It is telling you how high the water will be, at one place, at a series of moments — and the difference between those two things is most of what people get wrong about tides.
Our tide times page gives you the predicted highs and lows and names the station they came from. Here is how to read what it gives you.
The tide is the up and down
The CO-OPS glossary defines a tide as "the periodic rise and fall of a body of water resulting from gravitational interactions between Sun, Moon, and Earth" — specifically "the vertical component of the particulate motion of a tidal wave."
The sideways movement is a separate thing with a separate name. A current is "generally, a horizontal movement of water", and the glossary is firm about keeping the two apart: although the horizontal movement is part of the same phenomenon, "it is preferable to designate this motion as tidal current."
So a chart of highs and lows is a chart of water level. Which direction the water is running, and how hard, is a different prediction.
Flood and ebb
The two words worth knowing. A flood current is "the movement of a tidal current toward the shore or up a tidal river or estuary." An ebb current is "the movement of a tidal current away from shore or down a tidal river or estuary."
That is all they mean: water coming in, water going out.
Slack water is not necessarily high water
This is the part that catches people, and the honest answer is that it depends on where you fish.
Slack water is "the state of a tidal current when its speed is near zero, especially the moment when a reversing current changes direction and its speed is zero." You might reasonably assume that happens at high and low water. Sometimes it does. The CO-OPS glossary is explicit that it varies:
"The relation of the time of slack water to the tidal phases varies in different localities. For a perfect standing tidal wave, slack water occurs at the time of high and of low water, while for a perfect progressive tidal wave, slack water occurs midway between high and low water."
Read that again, because it is the whole lesson. In one place the current stops at high water. In another it stops halfway between high and low — three hours adrift of where you would have guessed. Your water sits somewhere between those two ideal cases, and no general article can tell you where.
There is a related word for the flat spot in the height: a stand of tide, "an interval at high or low water when there is no sensible change in the height of the tide." Strictly the water is stationary "for only an instant", but the change near the turn is slow enough that it does not feel like it.
The heights are measured from a datum
A tide height is not the depth of the water. It is a height above a reference level. The usual one is mean lower low water, which the glossary defines as "a tidal datum" — "the average of the lower low water height of each tidal day observed over the National Tidal Datum Epoch."
An average of low waters, in other words. So a prediction of two feet means two feet above that average, not two feet of water under your hull. What is actually beneath you is that datum-referenced chart depth plus the tide.
How far to trust the prediction
Predictions are astronomy. The water in front of you is astronomy plus weather.
NOAA Tides & Currents runs forecast models that fold the weather in — they "include water level deviations in the estuaries caused by wind and ocean water level changes", and are "accurate to within 6 inches 90% of the time." But those models depend on wind forecasts, and NOAA is candid about the horizon: "the wind and ocean water level forecasts are limited in their accuracy beyond one to two days, thus tide table predictions are probably better for longer term predictions."
Which is a useful rule in both directions. Planning next weekend, the tide table is your best tool. Judging what the water will actually do tomorrow morning in a hard onshore blow, it is not the only thing to look at.
Then let your own log settle it
A chart tells you what the water will do. It cannot tell you what your fish do about it, and anyone who says otherwise about your particular creek is guessing.
That is what a record is for. Note the stage you fished — not just "high tide", but what the water was doing — and after a season you will know whether the ebb really is better off your point, or whether you have been repeating a story. The fishing log guide covers what to write down.