Find the station and identify the series
The Canadian Hydrographic Service's tides, currents and water-level portal distinguishes observations, predictions, forecast levels and historical resources. Start with the station or area you actually need, then read the series label. A prediction curve can extend beyond the most recent observation without providing any new measurement. The portal also links to notices and station information. Check those alongside the graph instead of assuming that a visible line proves a sensor is reporting normally at this moment.
Why an observed level can differ from a tidal prediction
The CHS frequently asked questions distinguish astronomical tidal predictions from observed water levels and forecast products that incorporate additional information. A prediction is not designed to capture every weather-driven departure. The same FAQ explains chart datum as a vertical reference used for charted depths and tidal information. Before comparing two heights, confirm their reference systems. A number in metres is incomplete without that context, and values at different stations should not be treated as if they share an identical local zero.
Tide tables and current tables describe different motion
The Canadian Tide and Current Tables publication page separates high and low water times and heights from current timings and velocities. Select the correct region and annual edition when using a publication. A table for water height does not tell you a current's speed, and a current table does not provide a measured water level. The distinction is especially important when a search engine returns a downloaded table without the surrounding product description. Go back to the publication page to verify what you opened.
Make a careful comparison note
For each graph or table, record station, date range, time zone, units, datum and whether the values are observations, predictions or forecasts. If you compare a graph with an older download, check the edition and any notices before assigning meaning to a difference. A missing observation is a gap, not a level of zero. A flat-looking curve may reflect the displayed scale, so inspect the axis rather than comparing screenshots by shape alone. Keep original labels in a research note so another reader can reproduce the comparison and see what remains uncertain.
What this page adds to the ship explorer
PocketWorld provides an educational geographic view of available vessel reports. This article does not supply a CHS water-level layer, nautical chart, predicted current overlay or calculation of a vessel's clearance. Open the official services for those products, and keep their observations separate from the time attached to an AIS report. A nearby vessel icon cannot verify the accuracy of a water-level value or establish safe passage. When source data are unavailable or the reference settings are unclear, stop the comparison at that limitation rather than filling the gap with an estimate presented as fact.
Data sources
Official references are linked beside the explanations above. This educational guide does not report current marine conditions or provide navigation advice.