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

Gate distance (nm)

Required number in nm.

Boat speed (kt)

Required number in kt.

Adverse current (kt)

Required number in kt.

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

Calculate the hours needed to transit a tidal gate against an adverse current from the gate distance, boat speed, and current strength. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Transit time (h)

Returned number in h.

• 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.
• 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.

• Time to Start Line Calculator

  Calculate how many minutes it takes to reach the start line from the remaining distance and current boat speed.

• Current Correction Angle Calculator

  Compute the signed crab angle needed to oppose a current's cross-track component. Routes whose cross-current exceeds boat speed cannot be held.

• Current Gain Loss Calculator

  Calculate the distance gained or lost to the current along the course, with a favorable set positive and an adverse set negative.