VP DPS-A- running two different pitch propellers?

[BRICH1260]

I have the above duo prop drive. I have been running F5`s for several years now with decent results, all but reaching max RPM`s. Reaching max 4600 with the F5`s. Engine max is 5000rpm. I recently obtained a set of F4`s. Is it possible to run one F5 and one F4 propeller at the same time without any negative impacts?

 

[Scott Danforth]

While not ideal, I have run a mix of B5/B6 props with the small block and B7/B8 props with the big block. Usually when one of the props runs into an immovable object like earth or a sunken boat.

I would run the F4's or the I series (4-blade rear)

 

[QBhoy]

VP state in writing that it’s not recommended. But it is certainly possible. Some do.
All I’d say is that it is extremely unusual for a DP VP outdrive to be originally propped anything other than as good as it gets or near to. Usually when it’s reported otherwise…it’s things like leaving trim tabs down and dragging or not trimming the drive well, that cause the engine not to make its rpms as it should. Almost always there is a human factor like this involved to see such a thing. Or someone has messed with the props at some point.

 

[Texasmark]

So what's with running the same pitch or different pitches on one prop feeding the other prop? Maybe I need to get out the Volvo Penta encyclopedia and understand the physics behind the design.

 

[QBhoy]

So what's with running the same pitch or different pitches on one prop feeding the other prop? Maybe I need to get out the Volvo Penta encyclopedia and understand the physics behind the design.

I’d imagine one of the reasons behind it, would be uneven loading of that lengthy big contra prop shaft ? Who knows.

 

[BRICH1260]

So if I follow thru with this, would it be best to have the higher pitch prop in the front and lesser pitch in the rear, or vice versa?

 

[Texasmark]

So if I follow thru with this, would it be best to have the higher pitch prop in the front and lesser pitch in the rear, or vice versa?

Maybe this will help: https://www.volvopenta.com/parts/propellers/duoprop-for-aquamatic-sterndrive/