Estimate apparent wind, true wind, sailing angle, wind category, reefing concern, and sail trim guidance from wind speed, boat speed, and wind angle. This calculator is useful for sailors, coastal cruisers, dinghy sailors, lake sailing, passage planning, and comparing upwind, reaching, and downwind conditions.
True wind:
True wind is the wind measured relative to the water or ground, before boat motion changes what the crew feels onboard.
Apparent wind:
Apparent wind combines true wind with the boat’s motion. As a sailboat moves, the wind usually feels stronger and shifts farther forward.
Sailing guidance:
The calculator estimates point of sail, apparent wind speed and angle, reefing concern, sail trim notes, and trip time from entered speed and distance.
A sailing wind calculator helps estimate what the sails actually feel, compare upwind and downwind angles, and decide whether conditions suggest full sail, reefing, or a more conservative setup.
Actual sailing comfort and safety depend on gusts, sail area, reefing setup, sea state, boat design, crew skill, ballast, current, visibility, and forecast changes.
This calculator uses vector math to estimate apparent wind from true wind, true wind angle, and boat speed:
Apparent Wind = True Wind Vector + Boat Motion Wind Vector
Apparent wind is the wind felt on the boat. It combines true wind with the wind created by the boat moving through the water.
As the boat moves forward, it creates wind from ahead. That forward component pulls the apparent wind angle closer to the bow.
Reef when the boat is overpowered, heeling too much, hard to steer, or when gusts and waves make conditions uncomfortable. Many sailors reef before conditions become difficult.
Use apparent wind for sail trim because it is what the sails actually feel. True wind is useful for route planning and comparing weather conditions.