Piranha with a 4 blade

Discussion in 'Prop Shop' started by gbud1969@gmail.com, May 30, 2012.

  1. gbud1969@gmail.com

    gbud1969@gmail.com I Love my Piranha even more...

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    Help getting more out of my boat.
    I have a 14' Piranha with a Merc 50 ELPTO and a Trophy Sport 10.625 x 13p.
    It revs just over 5000 maybe 5100. WOT should be 5000-5500
    It gets out of the hole pretty fast and gets up to full power fast also. top end right now is about 34mph. Seem like I should be getting 40 +. Maybe I should be running a 3 blade?
    The hull weighs 420lbs, the engine 204lbs, two batt 100lbs, trolling motor 40lbs, CC steering cables hardware maybe another 100lbs, 12 gallons 70lbs, fishing gear with ice etc 40lbs and my wife and I 300lbs for a rough total of
    1274lbs
    Oh and at its widest spot its 72" here is a pic.
    [​IMG]

    Thanks in advance
    Glenn
     
  2. tom_in_orl

    tom_in_orl Founder of Microskiff, Member of the Gheenoe Army

    Hi Glen,

    I have the same motor and get 37 MPH with a heavy cupped 4 blade prop. Thats when the motor is absolutely tuned to perfection and running solo. I think you are not doing bad with your boat, two passengers and all your gear. 34 MPH is respectable. To get more I think you are right about having to try a 3 blade prop. The other big help would be a hydraulic jack plate. That would let you tune your set up to the max. Still I think you may be doing good if you get up to 36 - 37 MPH.

    If you absolutely feel the need for speed I believe that motor is the same block as the 60 ELPTO and could be upgraded. All it needs is the lower unit changed out to the 60's gear ratio, different carb jetting, and I think the right exhaust manifold.
     

  3. gbud1969@gmail.com

    gbud1969@gmail.com I Love my Piranha even more...

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    Sweet, thanks Tom. I'll get more accurate readings this weekend and post them. I would like to get a jack plate but I was thinking about a manual adjust type...
     
  4. tom_in_orl

    tom_in_orl Founder of Microskiff, Member of the Gheenoe Army

    A manual JP will help. More difficult to work with when making adjustments. Especially with a motor as heavy as the Merc 50 ELPTO.
     
  5. gbud1969@gmail.com

    gbud1969@gmail.com I Love my Piranha even more...

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    On the Gheenoe Classic, after I found the right height it stayed there and all I needed was the tilt and trim to jump on plane quickly. If I could keep from running more wires and less moving parts this seems the way to go. I dont mind if it takes me a few trips to get the right height and prop.
    I also forgot to add, When I try to get the boat out of the water (trim up) it starts porpoising. I will try a SE300 this weekend also. The SE200 did wonders for the Classic and I hope it will do the same for this one.
     
  6. gbud1969@gmail.com

    gbud1969@gmail.com I Love my Piranha even more...

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    OK
    So I was able to get out on Friday (yea I know it was nasty but I was able to fish ;D)
    I was not able to get a GPS signal for speed all day because of the cloud cover. I was able to get a good rpm reading, It was #@$ hair under 5000 and when trimmed up I got about 5050.
    I will say that I am in love with the SE300 foil I put on. It got me out of the hole in about 15' and it sure felt like I was going faster which I think is due to being able to trim the motor up more than I was and getting more of the boat out of the water. ( I do wish I was able to get a speed reading).
    When I was heading back in with the wind and rain in my face and trimmed up I was getting some chine walking and of course not much of the boat was in the water.

    I am thinking that when I do get the jack plate (Bobs more than likely) it may end up being the right prop (hopefully).
     
  7. gbud1969@gmail.com

    gbud1969@gmail.com I Love my Piranha even more...

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    Got out today for a bit. Was able to get a good GPS reading. At WOT it is running 36mph at 5050rpms.
    The only difference between now and the first post is the addition of the SE300 hydrofoil. Anyone that says these things don't work are nuts. I jump on plane in half the distance, Im able to trim it up more and run skinnier and it goes 2mph faster without porpoising.
    I cant wait to get a jack plate so I can turn it up another notch. ;)