resizing propeller

[Addis]

If the propeller currently be used can not be found, no more manufactured, can another larger propeller with different pitch be used and still have the same preformance?

 

[Sea Rider]

That's impossible to know if it has not been water tested with a tach. Assume larger props will have different size pitches to play with. OTOH was current delivered prop spot on for that setup ?

Happy Boating

 

[Frank Acampora]

Well, it would be nice to know the make of the engine and the horsepower BUT--Did you check ebay? For example: Simply type in Mercury propellers or Johnson propellers etc. Hundreds if not thousands of props are listed for sale, including obsolete ones.

 

[Addis]

My question is if I had a hypotetical 14 diameter X 15 pitch prop could I go to perhaphs a 15 diameter X either increase or decrease the pitch to have a comparable prop?

 

[steelespike]

Diameter doesn't enter into the equation as much at the pitch. Usually as pitch goes up diameter would go down
and viceversa.
Yes you could test with the larger diameter and adjust the pitch to compensate for any rpm problem.
If I remember right a 1" increase in diameter lowers rpm about 100.But in props diameter and pitch changes aren't carved in stone
results can vary widely.
When changing diameter you need to be sure you stay with a prop intended for your motor.
There is a strong possibility that going from 14 to 15"diameter prop that fits the prop shaft could be too big for the gear case.
And of course going from 15 to 14 may be too small for the gear case.
If you were going to try to force fit a prop I'd be looking for a diameter 1/4 to 1/2'" from original.

 

[Bondo]

Diameter doesn't enter into the equation as much at the pitch. Usually as pitch goes up diameter would go down
and viceversa.
Yes you could test with the larger diameter and adjust the pitch to compensate for any rpm problem.
If I remember right a 1" increase in diameter lowers rpm about 100.But in props diameter and pitch changes aren't carved in stone
results can vary widely.
When changing diameter you need to be sure you stay with a prop intended for your motor.
There is a strong possibility that going from 14 to 15"diameter prop that fits the prop shaft could be too big for the gear case.
And of course going from 15 to 14 may be too small for the gear case.
If you were going to try to force fit a prop I'd be looking for a diameter 1/4 to 1/2'" from original.

Ayuh,..... I agreed with most everything SSpike says,..... The bolded line I'll get to, but wanta expand on the prop hub diameter/ length thing,....

With Merc.s,... the mid-sized gearcase outboard motors, 'n the Large gear case outboard motors, use either the 4" prop bodies for the mid-sized motors, 'n the 4, 1/2" prop bodies for the large gear case outboard motors,...

Both of the prop body sizes will mount on the Large gear case outboards, but blow out because of the big air gap at the prop's leadin' edge,...
Obviously, the large bodied prop will slide onto the prop shaft of the mid-sized gear case outboards, but hits the gear case, regardless which thrust hub is used,...

So again, it comes down to what prop ya wanta try,... on what motor,....

Btw,..... The props that fit the Large gear case outboards, are also direct fit to the Alphas, 'n Bravos,...

'n for the bolded line, I gotta story,....
When my tinbarge had the ole 3.0l motor, 'n after I'd trashed the drive, I'd gotten a used drive that was for a V8,.....

On my last attempt at re-engineerin' this thing, after tryin' every prop 'round here, includin' a mid-sized gear case 13" prop that blew out wildly,...
I headed out with a 15"x15" for an Alpha,.... 2800 rpms,.... luggin', Badly,....

I pulled up to a Bud's dock, tied up, pulled the prop, 'n headed into his workshop,.....
I found an ole jigsaw that ran, 'n some blades for it, scribed a line, 1" from the blade tips inward,...
I sat there, 'n carved a full Inch off all three blades,... that's a full Two Inches total diameter, cut right Off,....
I cleaned up the cuts, 'n put it back on my barge, 'n headed out, thinkin' it'll Rev, Now,.....

Guess what,.... 2800 rpms, Wot, luggin to beat 'ell,....

I headed for the launch, 'n found me a 4.3LX,...... 'n another drive,.......

 

[Addis]

This is a stern drive unit i/o Volvo Penta 280 and not a outboard. Does that make a difference,
Trying different props is a little expensive seeing that there are twin drives.

 

[Bondo]

This is a stern drive unit i/o Volvo Penta 280 and not a outboard. Does that make a difference,
Trying different props is a little expensive seeing that there are twin drives.

Nope,.... Diameter plays a very tiny roll,....

 

[steelespike]

If you look up any prop for your setup lets say a 17" pitch 5 different brands all intended for your setup may all have the same diameter
or there may be 2 or 3 different diameters in the group. It isn't likely you will find a 17" prop that has a 1" different diameter unless it is intended for a difficult
application.I think its safe to say stay away from extreme diameter difference.
In your situation you may find a dealer willing to let you test props , with a sizable deposit and the understanding your going to buy 2 props.
Your probably have the complication that one prop is left hand rotation.Of course on the Volvo you can change rotation.

 

[Bondo]

I pulled up to a Bud's dock, tied up, pulled the prop, 'n headed into his workshop,.....
I found an ole jigsaw that ran, 'n some blades for it, scribed a line, 1" from the blade tips inward,...
I sat there, 'n carved a full Inch off all three blades,... that's a full Two Inches total diameter, cut right Off,....
I cleaned up the cuts, 'n put it back on my barge, 'n headed out, thinkin' it'll Rev, Now,.....

Guess what,.... 2800 rpms, Wot, luggin to beat 'ell,....

Ayuh,..... I stumbled onto some pictures of this prop I cut down,...
Still got it 'round here somewhere,... probably made a plant pot out of it, done alota those,...

'n one of my plant pots,...

 

[Addis]

I did not under stand your quote. It did or did not increase the r,p,m. I am guessing that they would.