DOTLAN EveMaps

The concept of the Apparent Wind:

The concept is introduced to simplify the study of the forces acting on a sail. By postulating an apparent wind we can consider a sail at rest with airflow over it. Thus, for example, we can use a wind tunnel to simulate actual sailing conditions. In a similar manner to the aircraft designer who can study the forces acting on a stationary aeroplane model operating in an airstream generated in the wind tunnel.

https://ladeas.no/