Field notes
Guides
Short explainers on what the water is doing and why — the theory behind every chart on Perigee's station pages.
How tide predictions work
Why NOAA can publish tide tables years ahead: harmonic constituents, tidal datums, and the difference between a prediction and what the water actually does.
How to read a tide chart
What the curve, the zero line, and a negative tide mean — and how to use high and low tide times to plan fishing, paddling, clamming, or a walk on the flats.
Spring tides, neap tides, and king tides
How the moon's phase and its distance from Earth set the size of the tide — and why the biggest tides of the year arrive when a full or new moon meets perigee.
Minus tides: the best days for tidepooling and clamming
What a minus tide is, why it exposes shore you never normally see, when the biggest ones cluster during the year, and how to plan a well-informed trip to the flats around one.
Why the tide is different every day
Why high tide arrives about 50 minutes later each day, why the two daily highs rarely match, and why some coasts get one tide a day while others get two.
Tidal datums: what tide heights actually measure
What MLLW, MHW, and mean sea level mean, why a tide height of 0.0 ft doesn't mean no water, and how to read datums when judging depth, clearance, or flood risk.
How sunrise and sunset times work
Why sunrise and sunset change by date and location, what dawn and dusk mean, how time zones affect the clock, and where to find today's exact local times.
How tides affect fishing: finding the useful water
There is no universal best tide for fishing. Learn how tide height, tidal current, shoreline access, moon-driven range, wind, and local structure shape a practical saltwater fishing window.
Flood, ebb, and slack water: how to read tidal currents
What flood, ebb, maximum current, and slack water mean; why they do not reliably line up with high and low tide; and how to read NOAA current predictions for a local waterway.
NOAA reference vs. subordinate tide stations
How NOAA predicts tides at reference and subordinate stations, why a nearby station can differ from its parent, and when high/low-only predictions are the correct local answer.