Use this sailing calculation for planning or education when the vessel, units, reference directions, environmental conditions, and assumptions are explicitly known.

Peak stream (kt)

Required number in kt. Peak stream rate quoted for mean springs.

Spring range (m)

Required number in m. Local spring range on the day.

Mean spring range (m)

Required number in m. Mean spring range for the reference station.

The cited overview of Tide supplies background for the terminology and domain context used by this tool.^[1]

Scale the published peak spring stream rate to the day's tidal range to estimate the speed of a tidal race. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Race speed (kt)

Returned number in kt. Estimated speed of the tidal race.

• Vessel design and loading, sea state, wind, current, tide datum, weather, chart accuracy, equipment, crew, and safety margins can make real conditions differ from a simplified result.
• Peak stream must be at least 0.
• Use finite inputs in the displayed units, preserve source measurements and assumptions, and independently verify consequential decisions.

Cross-check current charts, tide and weather services, instrument data, vessel manuals, and applicable navigation rules, and retain a conservative alternative plan.

• Overfalls Risk Factor

  Estimate the severity of overfalls from the spring tidal range, maximum stream rate, and water depth.

• Post-Tack Acceleration Time

  Estimate how long a boat needs to recover full speed after a tack from the speed deficit and the acceleration rate.

• Tidal Stream at Time Calculator

  Model the tidal stream as a sinusoid and return its signed rate at a given time into the flood-and-ebb cycle.