Thanks guys! Like the responses.
We are sailing a Dragonfly 28 Sport (i.e. tall rig). This is a very (for a tri) heavy boat at 2 220 kg's. We have the same sail area as a SeaCart 30 at more than twice the weight.
We need quite a lot of wind to really get going. Or a nice wind angle. When we get planning life is good but like Tomas and Sail(Plane) say, it is a question of playing the waves and finding the holes.
Apparent wind at 90 degrees seems to be the Hobie mantra. Yes, it is a good starting point. But then when the speed is up, I wish to maximize VMG down wind.
I find myself steering to the speedometer mostly. Which feels a little bit wrong.
We have a rudimentary polar diagram for two wind speeds. But speed varies very much on a trimaran.
Maybe one could start from the target boat speed, go up, go faster, go down, go lower than the angle at target boat speed, go up when speed is down to target boat speed. And repeat. (are you with me?). This will have us below target boat speed when we accelerate again but we are pointing below target angle so the price is not without benefit. What do you people think?