Tidal Observation Buoys and Beacons

A tide gauge, current meter, authoritative harbour display or published observation station can provide measured height or stream evidence. An ordinary navigation buoy or beacon does not automatically carry a live tide sensor; identify the actual service and variable before relying on it.

Compare observation and prediction only after checking that they use compatible datums and time bases. Read the station location, last update, quality flag and whether the measurement is height, stream or another sea-state variable. A remote gauge may not represent a shallow bar or narrow race.

Use disagreement as a trigger to increase margin and reassess the passage. The observation supplements the passage plan; it does not remove the need for charted depth, current publications, visual/radar evidence or a safe alternative.