wind point / wind speed

[bkw]

which is in sync with the masthead fly. the apparent wind reading on the gage or the true reading on the gage ? how can the instrument tell the difference between apparent or true when it is part of the boat?

[Faster]

Everything your wind instruments sense is apparent wind. If the wind instrument knows your boat speed, it can use that plus the apparent angle to calculate what the true wind speed and angle is.

[nolatom]

Apparent wind angle is what the mast telltale shows. If your instrument also shows true wind, then something (a knotmeter or a gps?) must be giving the instrument your boat's speed and direction, which vector it "subtracts" from the apparent (upwind) or "adds" to it (downwind) to get the "true" speed and direction.

[sailingdog]

Be careful though, if you're using a knotmeter for the speed and direction of the boat, the "true" wind can be off if there is a strong current.

[chrondi]

All these instruments should be properly calibrated if you need any degree of accuracy and reliability of the measurements! I think the angle reading is the most sensitive.