Dale, I’ve used both styles of that 9×8 prop on various 10 HP motors up to ’57 on my 14′ Smokercraft and my speed was about the same as yours, about 18-19 mph. What I noticed with the wider one is it seemed to push a slightly heavier load better, while the so called weedless one would reach max. rpms and plane the boat a little faster. But the difference in speed was barely noticeable between the two.
As they say, your mileage may vary.
