Picking a prop for a 1976 Glastron 16ft

[I Mow Grass]

To make a long story short we got into some really shallow water and the prop got all ate up. The boat is a 1976 Glastron 16ft with a 85HP Johnson motor. The current prop that is on it is a 13 1/4" drive and a 19" pitch.

We have been needing a new prop anyways to get more pop to get us out of the water for skiing. Being it does not have power trim this also is a big disadvantage for us skiing.

 

[junior1113]

Re: Picking a prop for a 1976 Glastron 16ft

do you remember what your wide open throttle rpms were with that old prop. i'd lean toward a 4 blade

 

[I Mow Grass]

Re: Picking a prop for a 1976 Glastron 16ft

There is no tach on the boat so I have no way of knowing, but judging by the sound I would say 4300-4900. I have heard that 3 Blade were better for the hole shot, is this not true?

 

[junior1113]

Re: Picking a prop for a 1976 Glastron 16ft

one more blade throwing water is enough said. scary not knowing what the rpms are. all i can say is that if your sure you are operating in recomended wot rpms which sould be around 5000-5500 rpms then i would go with a 17" pitch 4 blade

 

[I Mow Grass]

Re: Picking a prop for a 1976 Glastron 16ft

Well I will take along my tach I use on my cars have never even thought about that until now. If the RPMs are lower than what I said what will I need?

 

[junior1113]

Re: Picking a prop for a 1976 Glastron 16ft

down 2" pitch -up 300 wot rpms
up 2" pitch- down 300 wot rpms

as far as 4 blade it is rule of thumb that it will turn 150 rpms less than a 3blade of the same pitch

also 85hp is rated at 5000 wot rpms