prop slip question

[badbowtie]

I have two props to try test with one is a hustler turning point 21p the other one is a michigan wheel 21p I am pretty sure. They are both aluminum. The hustler is got 31% slip and will only rev to 4400. The michigan wheel has 40%slip but will rev to 5300rpm. I am more scared to try stainless steel for fear of hitting something. I really think I need a 19p that will only slip between 10-20 at the most and would perfect. I am trying to find someone that has a 19p ss to at least try but is there any aluminum props that will not slip as high?
Thanks in advance

 

[Tail_Gunner]

Re: prop slip question

Your Wellcraft should have far better numbers..How did you arrive at those numbers?? Think 12%...maybe 8-10

 

[badbowtie]

Re: prop slip question

I used this place http://www.go-fast.com/Prop_Slip_Calculator.htm

1.47 outdrive 21p hustler prop 4400 rpm gps speed 41.5 mph
1.47 outdrive 21p michigan prop 5300 rpm gps speed 43.6 mph

 

[Tail_Gunner]

Re: prop slip question

Is that a merc ourdrive or volvo>>>Somethings way off.....Is the hustler a new prop

You need to verify the tach and is that gps speed....Actually your tach of gearing is off....Your numbers give your a theor speed of 65 and with 10% slip 60....Thats a bit much for that hull motor combo

 

[badbowtie]

Re: prop slip question

It is mercruiser the hustler prop is brand new last summer used about 15 hours with zero marks not even a scuff. The michigan wheel is three years old with not one mark or smudge. I verified the tach and the gps last year it has been like this but just have not worried about it but would really like to dial it in.

 

[Kainon]

Re: prop slip question

Are you sure of the ratio ? what year drive do you have ? Or was the ratio changed ?

A note about RATIOS
Mercruiser updated the lower gear sets which changed the overall drive ratios.

What was a 1.50:1 is now a 1.47:1
What was a 1.65:1 is now a 1.62:1
What was a 1.84:1 is now a 1.81:1
What was a 1.98:1 is now a 1.94:1

 

[Tail_Gunner]

Re: prop slip question

Hmm if all of the above info is correct tach and pitch...I am certain you do not have 1.47 gearing..There is a way to determine final gearing...i just cant find the link...maybe spike or 45 or qc might wade in or someone who really knows...


Has that motor had any major perfromance mods done.....Doesnt matter...30% is way off

 

[badbowtie]

Re: prop slip question

It was a mercruiser 1.5 it is a 85 alpha one I changed it in the spring to SEI
drive 1.47 which the boat is acting the same as it did for a couple years.

 

[badbowtie]

Re: prop slip question

I just noticed you asked about the motor. Yes the motor has had some work done it is supposed to be bored 30 over I know the heads are ported for better flow and has a decent size cam.