Which prop should i use

Joined
Jun 24, 2008
Messages
8
I just purchased an 82 glastron with an 82 johnson 140 outboard. The previous owner was an avid water skier. He sold me the boat with a composite 4 blade prop on it.(for performance i guess) The boat does great with this prop. It planes out very quickly and does fine on mph as far as my speed needs go. My question is that in the deal he gave me two stainless props. a 17 and a 19. What would i gain by switching out the composite for either the 17 or the 19.
somebody help
thanks
 

K.P.

Seaman Apprentice
Joined
May 29, 2008
Messages
39
Re: Which prop should i use

What is the diameter and pitch of the composite prop?

What max RPM and MPH are you achieving with that prop?

I don't know the Max WOT RPM Range for that motor so you may want to find that out from a local shop or someone on this board may know.

The best thing you can do is just try out the other two props. As long as they are in decent condition, not chipped or bent.

My experience with composite props is they flex too much. I prefer the performance of a stainless prop even if I have to go down in pitch. Many stainless props provide better bow lift resulting in a smoother, drier ride. However, not all stainless props are created equal. Some do not perform well at all.
 
Joined
Jun 24, 2008
Messages
8
Re: Which prop should i use

the buyer told me the WOT was 5200 and cruise was 4800. I still am not sure why this is important but i know it is.
also
my rpm gauge has been working only part time. Some times it works well, sometimes not at all. What does fixing this entail?
I guess for my inexperience i am happy with the composite because i dont really know the difference. I am 6'3 and weigh about 220 and it pulls me out quick on 2 skis. I have not tried slalom. If i decide to put the other props on will i be able to use the same prop nut and everything?
does knowing the RPM at wot help answer my question of whether it would benefit me to change out the prop?
 

Silvertip

Supreme Mariner
Joined
Sep 22, 2003
Messages
28,758
Re: Which prop should i use

Not knowing what the pitch is of the current prop it is not possible to tell you what would happen with the 17 or 19. Keep in mind you have so many variables that even a prop designer couldn't tell you which is best. The prop you are running is a four blade composite of unknown pitch. The 17P affects performance as does 19P as does stainless vs composite, as does prop design, and we don't know whether the stainless props are from the same manufacturer and same prop design which are also variables. Your motor should be propped to run at 5500 RPM at WOT with an average load. The composite prop works well for skiing because of the flex at hole shot. It actually reduces pitch a little and then gets to its normal pitch as speed increases. The stainless props won't flex so if the composite is also a 17 or 19 it may actually get a better hole shot than either of the stainless. If your tach is intermittent, look for loose wires. Actually -- I should have said "check" for loose wires. You can't tell if a connection is loose by looking at it.
 
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