The real problem is that windvanes don't work well when the boat accelerates very quickly or reaches higher speeds. So performance oriented boats that can accelerate quickly bring the apparent wind forward, the vane adjusts slowly, then falls off again, repeats, etc. With the true wind behind the beam, this can lead to uncontrolled jibes. Vanes simply cannot react fast enough to boats operating at higher speeds. This can also result in unpredictable steerage.

Paul L described this for his J-37, which is hardly a racing boat, but is a performance cruiser. So there certainly are monos that cannot get suitable performance out of windvanes. For some, using a windvane would even be dangerous. In fact, there are many of this type of boat out there, and they are becoming more popular and numerous every year. Granted, there are probably fewer of them on the US West coast, like there are fewer catamarans there. But you will see that changing quickly.

Mark