Tide & Current Stations
BoatRoutes displays data from NOAA tide and current prediction stations throughout the Pacific Northwest. This data is essential for understanding water levels and tidal currents at your location and along your route.
Tide Stations
Section titled “Tide Stations”NOAA operates a network of tide stations that provide predicted tide heights. On BoatRoutes, tide station data appears as:
Sparkline Cards
Section titled “Sparkline Cards”Compact cards showing the tide height prediction over a 24-hour period. Each card displays:
- Station name — linked to the full station page
- Sparkline chart — a small line chart showing the daily tide curve
- High and low values — the predicted highest and lowest tides for the day
- Current height — the predicted height at the present time (or your selected departure time)
Daily Tide Curve
Section titled “Daily Tide Curve”On the station detail page, a larger chart shows:
- The complete tide height prediction for the selected date
- High and low tide times and heights, clearly labeled
- The current time marker (if viewing today)
- Rise/fall indicators showing whether the tide is currently coming in or going out
Current Stations
Section titled “Current Stations”NOAA current stations measure and predict tidal current speeds and directions. Current station data includes:
Sparkline Cards
Section titled “Sparkline Cards”Similar to tide stations, with:
- Station name — linked to the full station page
- Sparkline chart — showing current speed over 24 hours
- Max flood and ebb speeds — the strongest predicted currents in each direction
- Slack water times — when the current is at or near zero
Daily Current Curve
Section titled “Daily Current Curve”The station detail page shows:
- Current speed prediction for the selected date, with flood above the axis and ebb below
- Slack water times clearly marked (where the curve crosses zero)
- Maximum current times and speeds
- Direction indicators (flood vs. ebb)
Station Types
Section titled “Station Types”Harmonic stations — Primary stations with direct NOAA observations and predictions. These have the most accurate data.
Subordinate stations — Secondary stations whose predictions are derived from a nearby harmonic station using time and height corrections. Accuracy depends on the corrections applied.
Understanding the Data
Section titled “Understanding the Data”Tide Heights
Section titled “Tide Heights”- Heights are in feet above MLLW (Mean Lower Low Water) in US waters
- Heights are in meters above Chart Datum in Canadian waters
- Negative values mean the water level is below the charted reference — exercise extra caution in shallow areas
Current Speeds
Section titled “Current Speeds”- Speeds are in knots (nautical miles per hour)
- Flood currents flow inland (into Puget Sound, up channels)
- Ebb currents flow seaward (out of Puget Sound, down channels)
- Slack is the transition between flood and ebb (near-zero speed)
- Tide stations closest to your location give the best indication of local water levels. Be cautious about extrapolating data from distant stations, especially in complex waterways.
- Current stations are especially important near narrow passages. Check the current station data before transiting areas like Deception Pass or Active Pass.
- Predictions are based on astronomical tides. Actual water levels and currents can differ due to wind, barometric pressure, and river flow (especially in spring when snowmelt increases river discharge).
- Use station data alongside the route overlays to cross-check conditions for your planned departure time.
Station coverage by region
Section titled “Station coverage by region”Station density varies by cruising area. The coverage pages list the notable tide and current stations for each area and how well its passages are covered: