Took some work to figure this. There are 2 channel sizes. The 1 ratio is set for the largest channel size (from the circled top down to the thick blue) and the smaller ratios are set for the smaller channel size or .66406 of the 1 for that grid.
The steeper grid is exactly the same ratios and also uses the key point that is circled as the for the grids. Notice one grid is completely blues and the other grid is completely reds. The thicker lines for blue are the 1 ratio...and the thicker lines for the reds are the 1 ratio. All other ratios are .66406/2 .
The 2nd channel size (smaller) is .66406 of the 1 ratio and the smallest ratio is .66406/2 for both grids.