i know nothing about selecting the rite prop. i got a 20 hp chyrsler older not sure what year still trying to find out, any way i have a 14ft lund 1969. it seems like it dont want to get on top of the water. i can run it wide oppen and it spays water off the sides like crazy and seems like it wants to push water? i figgure it would kinda skip on top?? thanks if you have any info i am not even sure what prop is on there i would not know how to determen the pitch or sise.