18 waterman with 70 2 stroke

Discussion in 'Prop Shop' started by nsbsurfer15, Sep 9, 2014.

  1. nsbsurfer15

    nsbsurfer15 I Love microskiff.com!

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    Looking for advice on a 3 blade prop. Anybody with a 70 2 stroke on their waterman please chime in ! I have a 4 blade and its not anywhere where it should be as far as speed goes.

    I know it was addressed a couple threads below this one but that gentleman had a 60 4 stroke.

    Thanks !
     
  2. TC

    TC I Love microskiff.com!

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    I have an 07 18 Waterman with a 70 Yami 2 stroke. I have a PowerTech RED3R13PYM90 and a RED3R14PYM90. They both get on plane real quick, the hole shot's just a bit better with the 13. I'm seeing approx 35 mph with the 14, that's with two big guys and a full load. The 13 is just a tad slower top end. I prefer the 14.

    There's a couple of guys on here that have posted a little better numbers.
     

  3. reallyshallow

    reallyshallow I Love microskiff.com!

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    Do you have a jackplate?
     
  4. nsbsurfer15

    nsbsurfer15 I Love microskiff.com!

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    Yes, skiff has a jackplate. I have heard people achieve 38-39 with the right 3 blade.
     
  5. MariettaMike

    MariettaMike Wish'n I was Fish'n!

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    Some folks will report top speeds shown on their GPS while they are running with the current which can easily be 3-4 mph depending on conditions. Conversely some will report they are running slow when unknowingly heading into a current.

    I think you should try the PowerTech SCD3 in 15 pitch to see if you can replicate the 38-39 numbers, else drop down to the SCD3 14.

    For what its worth Yamaha ran a 17 pitch on a Skeeter bass boat to reach 38.3 mph at 5975 RPM.

    http://yamahaoutboards.com/sites/default/files/bulletins/bulletin_otb_2StrokePerf_HPMidPort_70hp_02-121-SKT-B.pdf
     
  6. nsbsurfer15

    nsbsurfer15 I Love microskiff.com!

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    My buddy had a 3 blade on his with what seemed like a ton of pitch. He can't remember the prop and he sold his skiff. He was about 38. I'll check into that SCB
     
  7. MariettaMike

    MariettaMike Wish'n I was Fish'n!

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    I have an old SCD3 17 you are welcome to try if you're in the Orlando area.
     
  8. Reel_Lucky2

    Reel_Lucky2 I Love microskiff.com!

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    A waterman with a tunnel is going to be relatively slow no matter what prop. They just aren't built for speed. That is probably the last consideration in the design. Hole shot and staying hooked up what high on the jack are what you should be maximizing with that boat IMHO. A 3 blade from Jack Foremann at crossroad props is a great choice for what I mentioned.
     
  9. nsbsurfer15

    nsbsurfer15 I Love microskiff.com!

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    The skiff does not have a tunnel
     
  10. reallyshallow

    reallyshallow I Love microskiff.com!

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    I have the same set up. I'm currently running the SCD4 17 pitch. Speeds between 36-38mph, runs best jacked all the way up and turns 56-58rpms trimming out and jacked up with no cavitation. If you have any other questions give me a shout. 7864234560 Ramiro.

    I'm in the process of ordering an SCD3 18 or 19 pitch and see if my top speed increases.
     
  11. nsbsurfer15

    nsbsurfer15 I Love microskiff.com!

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    I will take you up on that for sure !
     
  12. nsbsurfer15

    nsbsurfer15 I Love microskiff.com!

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    Let me know what your numbers are with the 3 blade ! that would be great
     
  13. MariettaMike

    MariettaMike Wish'n I was Fish'n!

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    You've got it. I also have a SCD4R16P you can try when "we" go fly fishing in your Waterman.
     
  14. nsbsurfer15

    nsbsurfer15 I Love microskiff.com!

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    Well, I tested out Mike's prop. It increased my speed from 33 to 37-38 mph. However, the RPMs were 5900-6000 at WOT, which is too high. If anybody else has any suggestions I am open to them.

    ReallyShallow, you get that 3 blade yet ??
     
  15. MariettaMike

    MariettaMike Wish'n I was Fish'n!

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    Theoretically you should have been running 40.7644 to 41.4533 mph at those rpm's. But that old 17" prop was slipping around 4-5%. If you go with an 18 the best you can get with no slip is 40.2361 at 5500. If it slips 4% you're back to 38.6266 at 5500.

    I also recall hearing a rule of thumb that rpm's will inversely change around 300 per inch of pitch. Go up to a 19 and WOT rpm's should drop to 5300-5400. 18 would be 5600-5700.

    Personally I think you would be better off going with a 4 blade SCD 17 to reduce slip across the board and have a solid 38-39 mph top end without having to raise the jack plate so much. The 4 blade SCD lifts the stern more than the 3 blade. (At least it does for my boat.)
     
  16. reallyshallow

    reallyshallow I Love microskiff.com!

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    I have not yet, I will tell you that with my SCD4 17 pitch I see speeds between 36-38 mph at 56-5800 rpms, trimmed out.  Those rpms are with the jackplate all the way up, and you can literally trimmed it out as much as you want without cavitation, the SCD4 has awesome grip.
     
  17. nsbsurfer15

    nsbsurfer15 I Love microskiff.com!

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    Well, I bought the SCD4 17 pitch and it has excellent grip and can be elevated all the way up on the jackplate w/o blowing out. However, I am still not getting proper RPMs and only getting 35 mph top end. I can only achieve 5500-5600 with it trimmed way out and jacked all the way up and it is not really effective as far as gaining more speed. With the jackplate set all the way down or 4", I can only achieve 4,900-5,000 RPM. I am going to try and stay with this prop but go down a pitch or 2.
     
  18. TC

    TC I Love microskiff.com!

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    Keep us posted please. Very interested in your numbers. Thanks!
     
  19. nsbsurfer15

    nsbsurfer15 I Love microskiff.com!

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    I talked with powertech this morning and they recommended dropping down to a either a 14 or 15 pitch in the SCD... 14 sounds a little low to me so I might try the 15. this is already starting to get expensive !! lol
     
  20. reallyshallow

    reallyshallow I Love microskiff.com!

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    Seems like powertech props are not all the same, I'm getting 56-5800 rpms at 36-38mph with my SCD4 17". Why not consider the SCD3 17"?