DUO PROPS

[Steven J]

I have a new boat with counter rotating stainless props. I had to change them to get into the proper rpm range. The question I have is when installing the second prop where should it be placed on the splines in relation to the primary prop. Should it be directly in the middle advaced back or forward. If you know. Please write a little. Thank you. Steven

 

[walleyehed]

Re: DUO PROPS

Are you talking about spacing between the 2 props, or blade location if refference to the front prop blades.???

 

[Stratocaster]

Re: DUO PROPS

I have heard that this matters, but I can't see how it does. As soon as the engine turns a fraction of a rev, the props have moved relative to each other. It doesn't say anything about this in the owners' manuals, so I would assume it's an urban legend.

 

[TilliamWe]

Re: DUO PROPS

I would assume it's an urban legend.

Nope not an urban legend. My owner's manual for my 1997 Mercruiser Bravo 3 has a section about R&I the props. On the Bravo 3 it does not matter how you put them back on... but on the now discontinued Blackhawk drive the props had to be "timed". They showed a picture of where to align the blades of the second prop in relation to the first.<br />If the drive in question here is a Volvo Penta DuoProp, I have no idea how to reinstall the props.

 

[Stratocaster]

Re: DUO PROPS

What I meant was that it's an urban legend about timing the props. I know the manuals describe how to R&I the props, my last boat had a VP DuoProp. But nothing about their orientation.

 

[TilliamWe]

Re: DUO PROPS

Strato, I can't see how it would matter either. But for some reason on that Blackhawk (which was close to a "surface drive"), it must have. I think the way it was illustrated was, you put the first prop on with one blade pointing straight up. Then you put the rear prop on so that one blade was pointed straight down. Maybe it was so you wouldn't have two blades straight up (and out of the water?) at the exact same time?