Faster Holeshot by Venting my Prop

Discussion in 'Prop Shop' started by BlackMolly775, Feb 9, 2013.

  1. Anyone using a Vented Prop? Nothing new, except that most "experts" say that all outboards will gain faster Holeshot via "controlled ventilation during acceleration" instead of said for years that only motors 50hp and up would benifit.

    Works by allowing the motor to turn higher rpm's under acceleration providing more power to plane thus getting increased holeshot without decressing Top End. Since I found a ton of poeple who just "vented" their existing prop I vented one of mine the other day via a few Vented Prop DIY diagrams. I used a S.S. Power Tech SRA3 12 pitch prop which gives me the best performance. I should be testing it the next couple of weeks along with some other things Plus waiting for another POS tiny tach.

    Pretty simple, but stayed conservative and drilled three small 7/32" holes near the base of each blade. Hopefully it works without any Motor timing, carb adj, throttle linkage adjustments etc.....
     
  2. Dillusion

    Dillusion devilray snob

    I was wondering this too lately, I almost did it- but decided to not mess anything up when not necessary. After having my 10x15 stainless cupped all the way down the edge of the blade my holeshot is fine and my top end didn't suffer more than 1mph loss from the cup.

    Technically you don't need to change anything inside the motor...the venting is just inducing a 'controlled by hole size' slip of the prop while in the hole and removal of said 'slip' when going forward because the exhaust gasses just channel out of the prop hub and midsection exhaust relief.
     

  3. paint it black

    paint it black Paddling away...

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    My Raker came with the vents on it. I know Ryan got his vented, and said it made a difference.
     
  4. Right,
    If I don't notice improvement then it gives a list to check at the motor.
     
  5. cutrunner

    cutrunner Cert. Yamaha technician

    Prop venting like previously mentioned is mainly for at least 50hp and up. The smaller motors (unless on a light little hydro or thin aluminum jon boat) just dont have any real torque. The small hole you drilled may help, but dont go much bigger or it will hurt it
     
  6. High + Dry Adventures

    High + Dry Adventures Welcome to the family!

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    I would recommend having it professionally done for the best performance.  You cant just drill the holes anywhere.




    Yep here it is! 

    You need to stopwatch your time to plane and see if it decreased.

    In theory... it has to do with the pressure inside the prop and the pressure on the outside of the prop.  The disrupted water caused by exhaust air bubbles allows the prop to spool up faster.  When the pressures equal the prop works the same as it did before.  That why u dont lose top end!

     :cool:

    Why you would gamble on drilling to risk having to do these adjustments is just asinine.  Anyone looking to do this, take it to a prop shop.  Thats what they do. The holes will be in the exact spot on every blade.  That will = performance. When it comes to safety and performance there is no "Hopefully"
     
  7. Sheremeta

    Sheremeta Well-Known Member

    I'm having Ken at prop Gods repitch and vent my 15p powertech to improve hole shot.
     
  8. Ken put up a diagram on another forum as a DIY. The holes did improve Hole Shot, but have yet to install my Tabs. Will talk with Ken in the next few days on another Prop.

    With my PT SRA3 12 pitch I'm doing 28.5mph solo, but would love to get over 30mph without sacrificing anything.
     
  9. Maybe just take the 1999 50hp Tohatsu S.S. I bought last year up to the Shop and replace it with my Mercury 25hp 2 stroke. ::)

    The 50hp does add about 45lbs. to my transom, but would also be running right around 42mph-44mph.









    [​IMG]
     
  10. cutrunner

    cutrunner Cert. Yamaha technician

  11. How about Binimi this summer?
     
  12. cutrunner

    cutrunner Cert. Yamaha technician

  13. Creek Runner

    Creek Runner Well-Known Member

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    Can I join in please?
     
  14. cutrunner

    cutrunner Cert. Yamaha technician

    We would let you in if you wouldnt of sold the bullet.. :p
     
  15. Creek Runner

    Creek Runner Well-Known Member

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    You mean I can't bring the STV I will even run the small prop! LOL!  ;D
     
  16. cutrunner

    cutrunner Cert. Yamaha technician

    You can bring it, just put a counter rotation prop on it and put it into reverse to move forward. Thats fair enough eh?
     
  17. Sheremeta

    Sheremeta Well-Known Member


    If you went to a 13 or 14p of the same model prop you may achieve that goal. What did Ken say? I'm extremely impressed with his knowledge and service.
     
  18. Len said that the Power Tech SRA3 props are about the fastest he has come across. Drop the pitch to 11 maybe 10 and add just a little cup to the tips to gain speed.

    I need to buy a Tach again, but I'm not sending another $50 to Tiny Tach. I have gone through a ton of them over the years and have 2 that read all kinds of crazy ****. They might as well be the $6 Tachs from China on EBay.

    Analog?Sendec?
     
  19. JBMitziSkiff

    JBMitziSkiff Ninja balance is the key... for a poling platfrom

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    I run a vented Powertech prop RXB4 I believe it is a 13pitch but need to look again.
    It will rip your head off coming out of the hole on my 40 Etec. Runs 32 with just me on a good day. 2 people runs 29-30.
     
  20. byrdseye

    byrdseye Well-Known Member

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    For what it's worth, I drilled out the vent holes on my 19p Viper to try and get a better holeshot with the 60 E-Tec and it really did make a difference. I'm at 7/16ths now and thinking about going to 1/2".
    Also, I have a 19p Rogue that I think I'll send to Frank & Jimmies for vent holes .......my little motor has a hard time spinning it up when my large friends are on board.