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onwa imarinex True Wind Speed and Direction Calculator

True Wind Speed and Direction Calculator

The concepts of True Wind Speed and Direction are crucial in Fluid Dynamics, particularly in applications related to Navigation and Sailing. ‘True wind’ is the actual speed and direction of the wind experienced by a stationary observer. ‘Apparent wind’, on the other hand, is what a moving observer experiences. This distinction is important because what sailors feel onboard isn’t the true wind, but the wind as altered by their own speed and direction. To make accurate navigational decisions, it’s necessary to calculate the true wind based on the apparent wind, actual vessel speed, and the apparent wind direction.

Example Formula

The calculation for the True Wind involves resolving the wind vector into its components, applying the ship’s velocity, and then recomposing the True Wind vector.

Here’s a simplified version:

VTW = sqrt((VAW × cos(A))2 + (VAW × sin(A) + Vs)2)

θTW = atan((VAW × sin(A) + Vs) / (VAW × cos(A)))


VTW is the True Wind Speed.

VAW is the Apparent Wind Speed.

Vs is the Actual Vessel Speed.

A is the Apparent Wind Direction.

θTW is the True Wind Direction.

Who wrote/refined the formula

These calculations are based on vector analysis, which is a fundamental part of Physics and Mathematics. They’ve been used by sailors and navigators for centuries, and while no specific individual is credited with their creation, they are the result of countless contributions to the fields of Mathematics and Physics.

Real Life Application

This calculation is crucial in navigation, particularly in sailing where the direction and speed of the wind directly affect the vessel’s course and speed. Sailors must often make course corrections based on the true wind to reach their destination efficiently.

Key individuals

in the discipline While there’s no specific individual credited with the formulation of these calculations, many have contributed to the related fields of Mathematics and Physics. Notably, Sir Isaac Newton’s work on laws of motion and gravitation laid the foundation for the development of classical mechanics, including concepts related to vector quantities like wind speed and direction.

Interesting Facts

This calculation is not only crucial in sailing but also in aeronautics. Pilots also have to calculate the true wind speed and direction to navigate correctly.

The ability to calculate true wind from apparent wind has been a game-changer for competitive sailing, allowing for better strategic decisions during races.


Sailing Calculator2 1

ONWA KW-360   Ultrasonic Wind speed and direction sensor

onwa imarinex ultrasonic wind sensor kw-360


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