Tides helps you understand tide height, high tides, and low tides for the selected Weather pin or route.
Use Tides to check how the water level changes over time, which tide station Orca is using, and how tide height may affect your route, anchorage, harbour entry, or shallow-water navigation.
What does it show?
The Tides tab shows forecast tide height for the selected location and selected time.
Unlike Rain, Wind, Waves, and Currents, Tides does not use a heatmap or animated particles. Instead, Orca shows nearby tide stations on the map and a tide height chart in the bottom sheet.
Map
The Tides map overlay shows tide station information visually for the selected area.
It includes:
Tide stations
Diamond shapes represent tide stationsSelected tide station
The selected tide station, which appears in blue with its name stated on the chart, is the station Orca is using for the tide forecast. This is usually the closest available tide station to the Weather pin or selected route location. Other nearby tide station names may also appear when you zoom in.
Weather pin or location along a route
Marks the location the tide forecast is being shown for and shows the tide phase and tide height for the selected time.
The tide phase icon depends on the phase of the tide, not the absolute tide height.
The arrow indicates whether the tide is rising or falling, and the fill level indicates how close the tide is to high or low tide.
Data source label
Appears in the bottom-right corner of the map or in the expanded tide information, depending on the view. The data source is currently either UKHO / Admiralty Tides or WorldTides, depending on the selected location.UKHO = United Kingdom Hydrographic Office
WT = World Tides
Bottom sheet
The bottom sheet contains the Tides weather chart. This is where you can inspect tide height over time. You can scroll the chart horizontally to move through the forecast.
Weather chart
The Tides weather chart shows:
Highest-height reference line
A grey line shows the highest tide height in the data range.
Tide height line chart
Shows tide height over time for the selected tide station.High and low tide annotations
Shows the forecast high and low tides, including the tide height values.Tide height value line
Shows tide height values over time.
Together, these let you compare tide height over time for the selected Weather pin or Route.
The tide height shown in the chart should correspond to the tide height shown on the map for the Weather pin or position along a route at the selected time.
The tide chart is scaled to the height range of the selected tide station. This means that curves from two different tide stations are not directly comparable just by looking at the visual height of the chart. Compare the actual tide height values, not only the shape of the curve.
Expanded view
The expanded Tides view shows more detail about the selected tide station and the upcoming highs and lows.
The expanded Tides view shows:
Station name
Station distance from the Weather pin or route location
Data source
All highs and lows for each day
How is it measured?
Tides are measured as tide height over time.
In Orca, tide height is shown relative to Chart Datum.
Chart Datum
Chart Datum is the vertical reference level used in navigational charts to measure water depths and tide heights.
Because chart depth and tide height use the same reference level, tide height can be combined with chart depth to estimate the actual water depth at a given time.
For example, if the charted depth is 2 metres and the tide height is 1 metre, the estimated water depth is about 3 metres.
Chart Datum can vary by region
Orca uses navigational charts provided by official hydrographic authorities through Electronic Navigational Charts, or ENCs. Each chart includes its own Chart Datum, defined by the hydrographic authority responsible for that region.
Orca displays chart data as provided by these charts and does not adjust or offset the Chart Datum.
Because Chart Datum is defined locally, the exact reference level may vary depending on the region.
Examples include:
Lowest Astronomical Tide (LAT) – commonly used in Europe.
Mean Lower Low Water (MLLW) – used in the United States.
In some areas, the Chart Datum may be close to LAT but not exactly identical, depending on the standards used by the local hydrographic authority.
Tide stations and measured data
Tide forecasts in Orca are based on nearby tide stations. The selected tide station is the station used for the tide height shown in the chart and on the map.
The tide height value shown on the Weather pin or route location should correspond to the tide height shown in the chart for the selected time.