Follow up to prop testing.
Thanks all for chiming in. My props on hand for testing are limited for now.
I switched back to the original fall test prop. 17.5 x 21 inch aluminum.
Torque roll. Is 50% of what it was. It's safe now at least. Dangerous
With the 17.5 x 21 cupped stainless.
Lost almost a knot at the top end. Who cares when the boat stops trying to kill you.
Tried a 17 x 23 cupped stainless. Gained back my top speed and reduced roll . Got a gut feeling that he boat was just not happy with that prop. I have data that shows not much advantage to this prop.
I have sent both stainless props out to have the cup removed. Also the good aluminum prop in for a balance and tune up. I will start over next week.