Sailing Calculators
Free online sailing calculators for course, tidal heights, hull speed, anchor scope, passage planning, and racing.
Anchor Scope Calculator
Calculate how much anchor chain or rope to let out based on water depth, boat freeboard, and weather conditions. Stay safe at anchor.
Apparent Wind Calculator
Calculate apparent wind speed and angle from true wind speed, true wind angle, and boat speed. Essential for sail trim and racing tactics.
Boat Fuel Range Calculator
Calculate your cruising range and engine endurance from tank capacity, fuel consumption, and speed. Includes safety reserve calculation.
Course to Steer Calculator
Calculate the compass heading to steer to counteract tidal current and leeway. Find the actual course made good and estimated speed over ground.
Hull Speed Calculator
Calculate the theoretical maximum hull speed of a displacement yacht or boat from its waterline length in feet or metres.
Mast Rake Calculator
Calculate mast rake angle from measurements. Optimize helm balance by adjusting mast rake on your sailboat.
Sail Area Calculator
Calculate total sail area for a sloop rig (mainsail + jib). Compute sail area-to-displacement ratio to assess boat performance.
Sailboat Heeling Angle Calculator
Estimate a sailboat heeling angle from wind pressure and righting moment. Understand the stability trade-off for different sail configurations.
Sailing Dead Reckoning Calculator
Calculate distance, speed, or time for boat passage planning. Solve for any variable using the fundamental D = S x T formula in nautical miles and knots.
Sailing Handicap Calculator (Portsmouth Yardstick)
Calculate corrected time for handicap sailing races using the Portsmouth Yardstick (PY) system. Compare two boats to find the race winner on corrected time.
Tidal Current Speed Calculator
Estimate tidal current speed at any time using the 50/90 rule. Enter maximum current and hours before/after slack water.
Tidal Height Calculator
Estimate the height of tide at any time between high and low water using the 1/12 rule. Find out if there is enough depth to enter a harbour or anchorage.