Prop Sugestion for 16' Boggy Creek Genesis Tunnel

Discussion in 'Prop Shop' started by mirrocraft, Dec 10, 2012.

  1. mirrocraft

    mirrocraft I Love microskiff.com!

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    I am running a 2013 Etec 50hp Tiller with a Viper 13 7/8" x 17 prop. Boat top speed is between 32-35mph depending on water surface & wind. The boat has a bit of stern squat and takes a bit longer to plane than I would want. It also looses it's bite (Slips) slightly while coming on plane. I am wondering if I should drop the pitch to 15" or go with a Rogue 4 blade. Boat is faster than I really need would rather have it jump up quiker and not loose its bite. Also the boat goes about 3mph as soon as it is put in gear. Too fast to troll. I kinda feel I have too agressive a prop. Please give me some pointers as a new prop is costly.
     
  2. fsae99

    fsae99 I Love microskiff.com!

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    Sounds to me if this is a text book case for compression plate/anti cav device.

    At 32-35 mph sounds like you are to the right operating rpm range. Going lower pitch may mean you are constantly running up against rev limiter.

    Does it lose bite on take in flat calm water or just in 1-2' seas? Is the motor mounted with cav plate level with bottom of the hull?

    Edit:

    I just remembered this boat. I'd try adjusting the jack plate down in 1" increments. this will improve bite and slow the idle speed a bit.
     

  3. mirrocraft

    mirrocraft I Love microskiff.com!

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    This happens in flat water with the jackplate all the way down. If I try and take off with the jackplate raised it cavitates worse. Would a four blade the same pitch help with the bite?
     
  4. Creek Runner

    Creek Runner Well-Known Member

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    Toadfish let's get toghter and run your boat, I will help you prop it out. Call John if you want a recommendation about my Technical back ground.

    With out running it; 4 blade sounds about right for what you are looking to accoplish.

    Do you have an RPM guage on your boat? RPM's would be helpful when trying to find the best prop.

    Carolina Jim how can you say that he is at the right operating range just by speed.   [smiley=1-mmm.gif]
     
  5. fsae99

    fsae99 I Love microskiff.com!

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    You have to know speed and prop pitch can not be done by speed alone.

    33.162 mph = (((5500/2.67))*60*17)/63360 and accounting for slippage.

    Etec WOT OR 5500-6000
     
  6. fsae99

    fsae99 I Love microskiff.com!

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    I'd take creek up on his offer. Also, 4 blade may be your solution. Hearing what is happening through the take off would be valuable.

    I believe your pitch is somewhat low a 4 blade of the same pitch would help with slippage issue.

    Do have to say that I am racking my brain to understand the effect the 4 blade of the same pitch would have on idle speed, assuming same in gear idle rpm's. I just ate a big lunch and I'm a little sleepy.
     
  7. mirrocraft

    mirrocraft I Love microskiff.com!

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    Creek i would like to meet you. Please pm me you number and best time.
     
  8. mirrocraft

    mirrocraft I Love microskiff.com!

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    Carolina Jim, i am concerned with the happy median between a slower troll and a quik hole shot. If top speed reached about 30mph i would be happy. As i get older it is less about speed and more about getting up quicker and comfort. Love the hull and layout just need better performance to make this boat perform at it's best. I am this far. I do appreciate your time.
     
  9. mirrocraft

    mirrocraft I Love microskiff.com!

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    The hull performs best about 26-28mph. If that helps.
     
  10. cutrunner

    cutrunner Cert. Yamaha technician

    Whats bothering me about all of this is that i want to say go with the 4 blade, but man... 13 7/8 diameter is a huge prop to swing on a 50hp imo. That blade area should make it jump up instantly..
    Whats the boat weigh (realisticly)?
    Even on my skiff a 13 7/8 kills my top end but snaps neck on holeshot.
    Im thinking that maybe its so much blade area that its lugging the motor.
    Maybe try a 13x 17. That drop in almost an inch "could" be what your looking for.
    Btw, you need a tach
     
  11. mirrocraft

    mirrocraft I Love microskiff.com!

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    The prop looks huge. It is so big it has less than a 1/2" from the Motors cavitation plate. Too close to install a bobs true tracker plate. Any added cavitation plate would have to be on top of the factory platte it's so close.
     
  12. mirrocraft

    mirrocraft I Love microskiff.com!

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    The hull is about 550lbs, outboard 250lbs, 12 gallons of fuel, 12 gallons in the live well and 250 for my fat azz.
     
  13. cutrunner

    cutrunner Cert. Yamaha technician

    Hmm imo thats alot of prop for the boat/weight (no offense).
    Im curious to see what creek has to say about my idea in my prior post
     
  14. fsae99

    fsae99 I Love microskiff.com!

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    While huge at 13 7/8D that 2.67:1 gear ratio ought to turn it with 17P.

    Seems to be more than one thing going on with sluggish take off and cavitation.

    Is there cavitation through the whole take off or just when it noses over?

    How are you setting the tabs for take off?

    I've never met creek personally but his posts would suggest that he will get you straight.
     
  15. Creek Runner

    Creek Runner Well-Known Member

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    I think it has to do with the fact that the viper has pretty aggressive rake which is not needed on your tunnel boat. That boat is going to ride pretty flat and trying to push the bow up is going to cause ventilation.

    I demo and reviewed another genesis, green center console with a Honda 60 on it. That boat unloaded would run about 42mph if I remember right and popped out of the hole with ease. Your boat should run comparably. I PM'd you my # just hit me up and we will get it figured out.
     
  16. fsae99

    fsae99 I Love microskiff.com!

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    Just curious if any testing has taken place?
     
  17. mirrocraft

    mirrocraft I Love microskiff.com!

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    Will be testing today once it warms up a bit. I am trying a Solas aluminum 12 3/4 x 17P 4 blade and the Bob's cavitation plate. Performance review later today.
     
  18. mirrocraft

    mirrocraft I Love microskiff.com!

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    The prop and plate made a big difference. Planes allot faster and keeps the bow down. Lost all the torque steer. Still got 32mph. Thanks for the help.