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Vented props

Discussion in 'The Outboard Church' started by dezertrider, Mar 31, 2012.

  1. dezertrider

    dezertrider Well-Known Member

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    I have a Bravo One 24p vented prop on my outboard. When I got it there was a option to purchase fittings to make the holes smaller. Do the vents only improve the bottom end? We plan on doing a lot of skiing this year and I want to keep the low end power but need a little more top end as I max my rpm pretty quickly. What do you suggest?
     
  2. STV_Keith

    STV_Keith Well-Known Member

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    Those are called PVS holes if it came from Mercury that way. There are inserts you can put in that shrink the size of the hole or block it off altogether. Depends on what you boat wants.

    The holes allow air/exhaust to escape in front of the blades and ventilate the prop. This helps break the prop loose when getting on plane. Outboards usually don't have a ton of torque down low, and could get stuck trying to get on plane. My Scarab would roll up to about 2800rpm, then sit there for a good 5-6 seconds before finally the boat got enough speed to start to roll over. With vented Bravos, it gets to that point, blows the prop loose and spins up to like 4500, and rockets on plane.

    If you want to talk to a prop guy about your options, I use Kevin @ R&R Prop Shop. 702-564-7502.
     
  3. Groper

    Groper Well-Known Member

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    Yes what Keith said.

    I have a 300xs on a 21RT and have tried a 26" Bravo 1 4 blade w/ 7/8" holes which works ok getting out of the hole. Then I tried the Hill 26" Eagle 4 blade it has a small hub, the exhaust gases go around the outside of the hub insted of through the inside. This Prop has worked the best for me sofar, its spins very quickly the bites and then takes off.

    However I have change my Engine Bracket and lowered the motor about 3' (it was too high with the set up I had which might have made it easy to spin the prop) so now i might have to go through the whole "what prop will work" better with my new set up, due the fact the the prop is much lower in the water. we'll see !!!
     
  4. CuttingEdgePropellers

    CuttingEdgePropellers Active Member

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    Above is correct regarding the ventilation to get on plane easier. As far as the top end numbers, I have seen where ventilated props have helped in the high end MPH but it is not a general rule. If you are running out of prop in the high end, feel free to give me a call or post me here and if that prop is close, we can possibly pitch that prop up enough for you or if not, we can discuss a higher pitch and what that might be to get you spot on.
    My Best,
    Greg Hittner
    Cutting Edge Propellers
    949-701-0900
     

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