I agree with most of your remarks, although I do think that the frequency of the boat itself is by definition different than the frequency of the waves. It will be tricky to separate them if they are close. I think when you saw two frequencies in your fourier analysis, this must be it - one of the boat and one of the sea.
In fact, some seas have two frequencies - the short wave and the long swell. They say on the North Sea, every seventh wave is a big one, where the wave coincides with the swell. Haven't experienced it yet, but when I get my setup working I'll run your fourier tool. Where is that tool, btw - haven't found it in the plugin and now left the openplotter on the boat.
The quaternation is one bridge too far for me yet, but if the result is the pure vertical component, it must be the wave, given the sensor is near the boat's centre of gravity *). If one can plot that curve, and make some footage of the plot along with the steering corrections of a good helmsman (which I am not), you can work towards phase-dependent steering corrections. I expect to see that on a wavetop a boat has a tendency to turn into the wind, and a helmsman steers against that.
*) if the wave go up and your boat goes down, it's time to disengage your autopilot
In fact, some seas have two frequencies - the short wave and the long swell. They say on the North Sea, every seventh wave is a big one, where the wave coincides with the swell. Haven't experienced it yet, but when I get my setup working I'll run your fourier tool. Where is that tool, btw - haven't found it in the plugin and now left the openplotter on the boat.
The quaternation is one bridge too far for me yet, but if the result is the pure vertical component, it must be the wave, given the sensor is near the boat's centre of gravity *). If one can plot that curve, and make some footage of the plot along with the steering corrections of a good helmsman (which I am not), you can work towards phase-dependent steering corrections. I expect to see that on a wavetop a boat has a tendency to turn into the wind, and a helmsman steers against that.
*) if the wave go up and your boat goes down, it's time to disengage your autopilot