Prop too small or pitch not enough?

[wasper235]

I have a 91 ranger 391V with a 91 150 Johnson Faststrike, Currently running a 14.5 x 24 raker. My question is should I go with a larger diameter prop or a higher pitch (14.5 x 26)? The engine is very stout, comes out of the hole like a bullet with very little bow lift, even when loaded heavy (full tanks,livewells, and two 200+ men) has very good eceleration at mid range but at WOT it is flirting with 5800 to 5900 RPM at about 52 to 53 mph. I wonder if i should be running it that may rpm, and should I reprop?

 

[steelespike]

Re: Prop too small or pitch not enough?

Your description seems to indicate more prop.but you appear to have 26% slip 12 or 13 is high normal.
Is your speed by gps?Do you know your gear ratio? a 26 could knock off about 400 rpm and slow the hole shot a little.
What is a Ranger 391 is it considered a fast hull?

 

[wasper235]

Re: Prop too small or pitch not enough?

Ranger 391V is a shallow V bass boat. Speed is by GPS. Don't know the gear ratio, and i think it would be considered a fast hull design.
Now that you mentioned slip, if I start to trim as soon as it gets up on plane it does slip some, and in slight turns at or near WOT if I don't trim it down just a little.
By the way thanks for replying.

 

[Philster]

Re: Prop too small or pitch not enough?

Takes a lot of gear reduction to knock a 24p prop of that size down to low 50's.

 

[steelespike]

Re: Prop too small or pitch not enough?

Before investing in a prop you should varify the tach. then try lowering the motor one hole.
Is there anything like tabs or a transducer disturbing the water ahead of the prop?Does the boat lay down flat like its glued to the water? perhaps a hydro foil on the motor? Does the boat respond to up trim.
The 24" at 5900 with 10% slip would run about 64 mph.
So we need to figure out if your tach is wrong.We know your speed is right.
Your gps is set for mph not knots? if it was knots mph would be about 61.

 

[wasper235]

Re: Prop too small or pitch not enough?

I will verify tach this weekend. There is nothing in front of the prop. If i look at the lower unit on the trailer the prop looks well below the bottom of the hull. As far as trim, it does respond well. At WOT and full trim there is only the back of the boat in the water.
I did double check my gps and it is set to MPH.