True vs. Apparent Wind

How boat motion changes the true wind. We sail by apparent wind, which is the wind that your boat feels.
thesailingacad...
thesailingacad...
The Sailing Academy
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[@michaelcarman-yv9tm]

what's the point in this? i've sailed for years w/o knowing this. what's the wind vane at top of my mast for?

[@davidhmws]

In a way you're right. If you learn to sail, you learn by feel how much to sheet in the sail for a given wind velocity, boat velocity, and desired direction of travel relative to the true wind. This discussion only explains what is happening above the water, there is also the physics of what is happening below the water with the keel/fin/foil and boat shape, so ultimately by experience you figure out how to get from A to B. It's a partially self-correcting system. If you don't sheet in the sail enough relative to the apparent wind, the board will slow down until the sail is sheeted in correctly. However, If you are going fast and you sheet the sail in too much, the sail will stall and you will just slow down, system won't correct itself.

[@michaelcarman-yv9tm]

@@davidhmws ok then