Trying to figure out right prop.

[zell66]

1) Performance issue you are trying to correct.

More top end than hole shot.

2) Current prop manufacturer, model, aluminum or stainless as a minimum.

Michigan wheel 15x17 RH 17spline

3) Current prop diameter and pitch (required).

15 x 17

4) Wide open throttle RPM and speed with an average load (very helpful)

4200 to 4400

5) Engine/drive make, model, year, and HP

Volvo 4 cyl, AQ125, penta 270 out-drive 1982-83 and 125 hp

6) Boat make model, year, length and weight

Bayliner Capri 1982-83, 19.5' ??2200#??

Want to get best top end for my 4 cyl engine. Also what are pro's and con's of going with after market prop.? Is there a benefit to a 3 blade or a 4 blade prop.? Lastly I want to stick with Aluminum prop because of the bodies of water in my area, lot of stumps and floating crap.

 

[jestor68]

Re: Trying to figure out right prop.

Your Volvo AQ 125 is actually 117 HP. Max rpm is 5000. Your little Volvo would be happier turning more rpm.

Putting a smaller diameter prop( 14 X 17 ) on there will make it easier for the motor to spin it up a few more rpm; which might result in a little more speed. A 4 blade prop will usually produce less speed than a 3 blade.

But frankly, you cannot expect more than mid thirty's out of that little motor on a 19 ft boat.

 

[steelespike]

Re: Trying to figure out right prop.

As jestor suggests there is only just so much you can expect from your setup
and as he says a 3 blade will produce more speed than a 4.
If you get us your gps speed and rpm at wot it would help tell more about your present setup.
Some cells have a gps app.Also would help to know your gear ratio sometimes on a tag or stamped on the out drive.
A description of your hole shot and the boats performance with added weight.

 

[Don S]

Re: Trying to figure out right prop.

4) Wide open throttle RPM and speed with an average load (very helpful)

4200 to 4400

If you are only getting that rpm out of a 15x17 prop then you have engine problems, wrong gear ratio in the drive, the drive is tilted down too low and the bow is plowing, or the boat is water logged and weighs an extra ton or two.

 

[zell66]

Re: Trying to figure out right prop.

I will try and get boat on water this weekend and run it with just me and record the RPM's along with GPS speed.

It wont be a true reading but close, prop. got a little damaged end of last year but it should give us a better idea of what is going on. Will follow up this weekend