What prop is this . ?

[Baja Boater]

I have a Baja 16' Speedboat . .. 115 Mariner OB .. Bent the prop on the ramp ... Bummer. . Stuff happens. .. The number on the casting is P 7 413 .. aluminum - three blade
The current performance is okay. I would like to get better gas mileage if possible .. Top speed or hole shot not a big deal one way or the other . . Normally ride one or two people. .
I have a Precision Turbo M - according to the info on the casting - 13 1/4 x 24 Stainless. It came off a Mercury 100 OB on a bass boat . . I never ran it .. picked the boat up for parts .. I tried it on the Baja and it did not perform . .. maybe too much pitch for my usage . .. It is larger diameter than the one on the Mariner now . .. Trying to make sense of the offerings online ..

Thanks... not much to go on ... but thanks anyway .... your guess will be better than mine for sure . .. not hoping for the 'perfect' answer or prop . .

 

[Chris1956]

The 24P prop is likely too much pitch for your motor. You probably need a 19 or 21P prop. You have power tilt? Of course the only way to know is by trial and error. Prop it so she will spin at 5500 or so, with normal weight and max trim.

I would recommend the 3 blade Turning Point Hustler.

 

[Baja Boater]

Yes on power trim .... What diameter is that ? Looks like a 10 1'8 on initial search ..

 

[Baja Boater]

Overton's rep suggested a 4 blade . .. 13 diam .. 15 pitch for better gas mileage .. and I need a hub kit to go with it .. This is very confusing to me. .. Have not been able to catch up with the local prop guy ... Bummer

 

[Baja Boater]

So i put the 24 pitch on since the aluminum one was bent pretty badly. WOT was about 4300 . .. speed about 45 .. by the speedometer on the boat . . who knows how accurate either of those are for sure. . Faster than the aluminum one. . . at least for now I do not need to spend any money ... From reading other posts,, typical 1 inch pitch change is 500 rpm .. not exact math .. but . . so by that a 13x22 should be a pretty good fit . . Still curious what the aluminum one is . . Appears to be a 13 inch diameter ...no clue to pitch . ..
Thanks for the repies

 

[steelespike]

Check for numbers under the prop nut.115 prior to 86 5000 to 5500. After 88 4750 to 5250.
A good prop shop could lower the pitch and even remove some cup.

 

[Baja Boater]

What would be the harm is using the prop as is ? I only use the boat to ride around . . usually around 3000 rpm ... only put to WOT to see what the result would be ..

 

[Bondo]

WOT was about 4300 .
What would be the harm is using the prop as is ?

Ayuh,.... Welcome Aboard,... Big holes in the pistons,.... Yer luggin' the motor, throughout the rpm range,.....

 

[Baja Boater]

Finally caught up with the local prop guy. Answered my basic questions about the prop. The number stamped on the hub is a rebuilder's code . There is no number anywhere on the prop to tell manufacture's part number. He says it is a Michigan prop ... 13" probably 21 pitch. Can measure it once rebuilt. Says he can repitch the SS prop one inch and it would add 100 - 150 rpm to WOT.. So keep it for a spare or trade or sell . . Okay to use in the short term .

Suggests a four blade for gas MPG .. lose a little on top speed . . gain in many other ways .. Height on transom is a crap shoot . .. trial and error .. till you find what works best for the particular boat / owner needs. I was curious about that ..

By trimming it yesterday .. I got just over 5000 at WOT . . 50 mph . good response .. but hard to get on plane from a standstill. I now at least have something to go by as a starting point .

Thanks for all the replies. .