Advise on a new prop?

[fat fanny]

I will be purchasing a new prop in a week or so and would like some advise on what size and pitch to use on my 175 five series Sea Ray open bow (1996 3.0 LX w/ alpha 1 gen 2 outdrive) I have noticed over the last two years that my rpms have been trying to exceed the maximum save zone of my power package past 3800. any advise would be great trying to reach @ least a safe 35 to 40 mph when I normalkly have to push the limit to get 35 with 2 adults and two small kids.

 

[steelespike]

Re: Advise on a new prop?

I'm pretty sure your max rated rpm is something like 4,600.It may appear on a label on the motor.What is the present prop.Numbers usually appear under the prop nut.
We need the prop size,your present max rpm and speed (by gps if possible)
your rpm shouldn't be changing unless your bottom is getting fouled or the prop is getting dinged up the boat is holding water in the foam under the floor.Ususally a sound,well tuned 3.0 is good for around 40 at about 4,600 rpm.

 

[woosterken]

Re: Advise on a new prop?

FF,
i sent you a PM with some info on props
hope this helps.

woosterken

 

[fat fanny]

Re: Advise on a new prop?

I f I lean on it the rpm is 4200 and speed just below 37 to 35 the prop IF MY MEASUREMENTS ARE CORRECT IS A 14"dia &19"pitch??? but allot of the edges are pretty bad. Also boats hull is very clean and the foam is not water logged numbers on the hub are no longer readable.

 

[hwsiii]

Re: Advise on a new prop?

Fanny, I show your prop slip to be at 8%, and that is very good. Running a 19" pitch prop with a gear ratio of 1.94:1 at 4,200 RPM and 36 MPH you are in pretty good shape. I would bring the prop to a prop shop and have them fix the dings in the edges and you should be able to increase your RPM by about 200 RPM and that will be right at the middle of your recommended RPM range.

Prop Slip

H

 

[fat fanny]

Re: Advise on a new prop?

hwsiii
Thats exactly what I calculated w/ the formula and description I copied off a post of yours the posible loss of performance is due to damage to the leding edges dings,missing material and such. This comming week I will be repairing the radius's and reblending. I will also be buying another NEW spare who do you suggest for a good manufacture not to exspensive for my rig staying w/ the three blade aluminum ? Thanx for the help! and merry xmas