Older 225 hp Yami on 80's vintage Sceptre

[Bigshrimpin]

Prop calc
http://www.go-fast.com/Prop_Slip_Calculator.htm

OX66 ratio is 1.81


Let's assume it's a 15P prop the boat would have 18% prop slip to get 30mph at 4700rpm with a 1.81 ratio. 18% prop slip is awful.

17P would be 29% prop slip which is cement barge awful.