I was back to looking at boat wake when we went up Catbells. There were unusual features to the pattern in the bit circled. I looked up the Kelvin wake again - must learn how to do the theory.
https://en.wikipedia.org/wiki/Wake It asserts that the angle between the arrow and the red line should be 19.47 degrees. Also, the wavelets I've coloured yellow ought to be at 53 degrees to the arrow. I will try to get photographs from an angle that allow proper measurement.
