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

Tack count

Required integer. Number of tacks performed.

Boat length (m)

Required number in m. Overall length of the boat.

Boat lengths lost per tack

Optional number. Boat lengths lost for each tack.

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

Estimate the distance lost to tacking from the number of tacks, boat length, and boat lengths lost per tack. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Distance lost (nm)

Returned number in nm. Total distance lost to tacking.

• 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.
• Tack count must be at least 1.
• Boat lengths lost per tack must be at least 0.
• Boat lengths lost per tack must be no greater than 10.
• 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.

• Gybe Loss Distance

  Estimate the distance lost to gybing from the number of gybes, boat length, and boat lengths lost per gybe.

• Maneuver Time Loss

  Compute the total time and distance lost to a series of maneuvers from the maneuver count, seconds lost per maneuver, and boat speed.

• 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.