OK I will join the frey on what prop should I use

[mphy98]

Looking at replacing the old dinged up prop on the 79 thundercraft. 18' with 140hp gm motor, 198r drive. I have a new spare 21pitch prop that seems ok, but someone here said that they didn't think that would be the right one. I get 37 mph by gps loaded with 4 adults and a LOT of gear. This is just for Canada fishing, lots of rocks, maybe once or twice a trip if it iw warm enough up there to pull a tube. so What prop would fit my needs best? thanks as always, bob

 

[junior1113]

Re: OK I will join the frey on what prop should I use

rpm and speed @wot ?

 

[mphy98]

Re: OK I will join the frey on what prop should I use

4500 rpm @wot 37 mph per gps

 

[junior1113]

Re: OK I will join the frey on what prop should I use

#'s sound good to me thats about where you need to be. this is with a new 21p 3 blade right? alluminum or ss? what are you looking to improve?

 

[mphy98]

Re: OK I will join the frey on what prop should I use

that prop is alum, just heard from someone else that it was to big a pitch for that motor boat combo. thanks bob

 

[junior1113]

Re: OK I will join the frey on what prop should I use

ok 4500 @37 mph w/ a 21pitch alluminum prop. it has nothing to do with what you hear it has to do with what prop lets you spin within upper limits of recomended rpm for ypour motor. ss is whats going to give better performance. id put a stern drive ss 4 bladed 19 pitch on her and get more out of your boat. better hole shots, fuel economy, handleing, top speed, and slower runing speeds. all around better performance. i guess you could find a good aggressive ss 3blade 19 p with cup and rake if your scared of the 4 blade . this boat you see has a 4 and can ride in 4' swells without loseing speed at cruising speeds with a 3 i would slow down speed up slow down ect.