Taking polars on big boats is easy. Most already have the instruments to do the job. Attach a laptop to the
data bus, sail the required course, reduce the data and plot it out.

With beach cats, the problem is the wind speed and direction.

You could take a GPS (that will record and output the course and speed) and spend an afternoon buzzing around a weather buoy whose data is available online. If you have a laptop that can interface to a NEMA bus, find a monohull with wind and compass, that will anchor out and let you buzz them. Get a couple of boats and swap out the GPS

Polars are useful to beach cats, especially if you convert them to relative wind direction. They give you a starting point on angles. For example, they tell you real fast to sail a Tornado hot and sail deeper and higher on a A-class. They also told me that it sucks to be on a 5.5uni when the wind is over 15, except downwind. I am still looking for my data files.