2019 Cobia 320CC w/ Yamaha 300’s

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  • 2019 Cobia 320CC w/ Yamaha 300’s

    Normal load 2 people, 250 gals fuel, 20 fresh water and one cooler. WOT 52mph At 5200 rpm 1.0 mpg. 30mph at 3600rpm 1.8 mpg. Props SWSII 3x15x20. Any suggestions to improve performance and economy​​​​​​?

  • #2
    Originally posted by Priceless View Post
    Normal load 2 people, 250 gals fuel, 20 fresh water and one cooler. WOT 52mph At 5200 rpm 1.0 mpg. 30mph at 3600rpm 1.8 mpg. Props SWSII 3x15x20. Any suggestions to improve performance and economy​​​​​​?
    The WOT rpms are way low.
    One way to get better rpm is to lower the pitch, in doing that it affects speed and economy.
    I would want to look at engine height.
    Traditionally manufacturers mount engines a bit low.
    That's a fair amount of boat for those engines.
    Engine Sales and Service
    Ph +1 954.463.1515
    Fx +1
    954.463.4904
    Toll Free: 800.622.6747

    [email protected]
    www.parkeryacht.com

    Member of the MSHS Group

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    • #3
      Engines are set at the second hole. Cavitation plates are even with the bottom of the hull. Boat is approx 12,000 lbs. it’s not a go fast center console but looking to get the most out the Yamaha 300’s.

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      • #4
        Originally posted by Priceless View Post
        Engines are set at the second hole. Cavitation plates are even with the bottom of the hull. Boat is approx 12,000 lbs. it’s not a go fast center console but looking to get the most out the Yamaha 300’s.
        Boat is on the cusp of Trips or a larger (HP) set of twins.
        You definitely need more WOT rpm, approx 800. I would raise the engines a hole, if not two. And test again. Still make take some playing with the props.
        Engine Sales and Service
        Ph +1 954.463.1515
        Fx +1
        954.463.4904
        Toll Free: 800.622.6747

        [email protected]
        www.parkeryacht.com

        Member of the MSHS Group

        Comment


        • #5
          I'd like to see what 17 pitch Quicksilver Q4's would do.
          Should accelerate MUCH stronger and have good bite.
          probably loose 1 or 2 MPH on top end, but motors would be a lot happier.
          can test a set for 30 each plus shipping.

          Ken Reeves
          [email protected]
          941-735-5808

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          • #6
            Ken, I will call tomorrow. Thanks for you assistance!

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            • #7
              Props are on. Here are the results. 30 mpg, 3700 rpm, 1.67 mpg, 17.8 gph. WOT 50 mph, 5800 rpm, .97 mpg, 52.3 gph. Bow rise greatly reduced, acceleration vastly improved. May still raise motors one hole. Thoughts?
              Last edited by Priceless; 10-12-2019, 05:38 PM.

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              • #8
                Numbers sound great !, RPM and speed is about what we expected.
                if you think you can raise the motors a hole, you might get that couple MPH back and maybe help the cruise economy a little.

                Ken Reeves
                [email protected]ds.com
                941-735-5808

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