Autowind switching True Wind / Apparent Wind

[ironman]

Could there be a setting that automatically switches to Apperent Wind mode when AWA < 90 degrees, and to True Wind when AWA > 90 degrees. This seems to be implemented in some autopilots, and it coincides with the practice I seem to be following with my pypilot.

[seandepagnier]

it would be easy to implement

I am wondering.. how does true wind mode work? Do you find it useful? I have very little feedback about using this mode.

[ironman]

The theory is that on broad courses, with inherently following seas, the boat speed might change more due to surfing up and down waves. With the STW undulating, so does the AWA, and the pilot might steer a curve instead of a straight line. With the risk of broaching and gybing, you're better off steering by TWA.

On a beat, you want to maintain a constant AWA to get the most out of wind shifts, while still preventing stalling due to the wind turning dead ahead.

So on a reach, your strategy is risk-mitigation, while on a beat, it's performance.

This theory I've adopted so far and it gives me the impression of a calmer ride either way. Nothing scientific. Some forum thread got me to realize this would be great functionality for an autopilot. It would not be a big thing to change the wind mode manually, but one typically forgets.

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BTW, currently pypilot determines TWA based on SOG. In general, and in tidal waters in particular, it's better to determine it based on STW. But I realize there's no speed log yet in the pypilot omniverse...

[seandepagnier]

So to confirm, this is theoretical.. I was waiting for practical use of true wind mode first before implementing such a feature.

I agree that water speed is preferred over gps speed, but as you say, there is no waterspeed available for the most part.