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

Total resistance (N)

Required number in N. Total hull resistance at the operating speed.

Wave making resistance (N)

Required number in N. Wave making component of the hull resistance.

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

Compute the wave making share of total hull resistance using wavemakingRatioPercent = waveResistanceNewtons / totalResistanceNewtons * 100. Inputs are interpreted exactly in the displayed units and the calculation returns the following fields without presentation rounding.

Wavemaking ratio (%)

Returned number in %. Percentage of total resistance attributable to wave making.

• 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.
• Total resistance must be at least 0.
• Wave making resistance 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.

• Ballast Ratio Calculator

  Compute a sailboat's ballast ratio using ballastRatioPercent = ballastWeightPounds / displacementPounds * 100.

• Frictional Resistance

  Compute frictional hull resistance using frictionalResistanceNewtons = 0.5 * 1025 * speedMs^2 * wettedAreaM2 * frictionCoefficient with a default coefficient of 0.004.

• Anchor Scope Ratio Calculator

  Compute the scope ratio from the deployed rode length and the total height to the bow chock.