AA Butterfly versus CNv LCD wind calculation

Thanks for confirming my question that a fixed magnetic compass provides the fastest and best wind speed/direction calculation. It is also impressive how much others have done (even 20 years ago) to build algorithms which calculate great wind info without the fixed compass.

Racing sailboat instrumentation today (and for the past 20 years or so) is also extremely advanced at calculating "true wind speed" and "true wind direction." Imagine how important it is for a sailing team to understand what the "TRUE" wind direction and speed actually is! The funny thing is that on a moving sailboat (especially a fast moving sailboat) "true" wind direction and speed is actually very difficult to calculate accurately. Modern boats are accelerating and decelerating rapidly and make almost constant course adjustments. Modern sailboats are very high performance, especially downwind, especially multihulls or foiling boats. This performance (huge advanced sailplans, lightweight and powerful and efficient hull shapes) create racing sailboats which develop significant "apparent wind." Apparent wind essentially "bends" the true wind forward as the boat builds speed as much as 120 degrees from the "true" direction as the boats forward speed creates considerable additional wind energy. This energy fluctuates greatly as the boat changes speed and direction to maximize its speed as the true wind changes. Accurate true wind speed and direction data is extremely important for calculating what polar speed is optimum and (equally important) for what tack is favored towards the next mark (SMG, speed made good and SMGT, speed made good (optimum) other tack). The sailors are constantly referencing key instruments for optimum heading (apparent wind angle) and boatspeed in order to stay on the optimum polar heading and speed. This is exactly the same as when a glider references "speed to fly" and changes pitch (1 dimension vs 2 on a sailboat) to stay at the optimum polar speed for the current lift shown on the speed to fly vario. Sailing teams spend many, many thousands of dollars buying and countless hours optimizing these instruments (just as glider pilots do) but sailors actually have a much more critical tactical need for the instantaneous and accuarate true wind data.

For whatever it is worth.

Sean