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  1. #1
    dhoad's Avatar
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    What next for handling

    First let me start by thanking eveybody on the forum for all the info. With stuff learned here I hit a peak speed of 75 at 7100 rpm last weekend on gps and consistently hit 72.5. Special thanks to Fernando, Carl, Jim and Art for lots of hand holding (by phone) as it was the first time I'd worked on a ski.
    Anyhow, I need a little better safety/stability at speed. When I chop the throttle at speed the ass off the boat rises, is this due to pump overstuffing or is just cuz I'm going way faster than in the past and a variant of normal. Would 1200 grate help this?
    Also, when encountering chop (I ride on smooth inland lakes with only boat wake to mess up normal glass conditions) I seem to bounce and come unhooked loosing some control and directional stability.
    My sponsons are all the way up - I will try stepping them this weekend.
    What should I start with for shimming plate and tabs?
    Thanks
    Doug


  2. #2
    Moderator RX951's Avatar
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    Nice speed and welcome to the forum dhoad !

    Its nice to see another fast 12R on the forum !

    My sponsons are all the way up - I will try stepping them this weekend.

    Try stepping your sponsons first and see what that does for the porpoising.

  3. #3
    Flying Scotsman's Avatar
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    Doug you need to hook up with Chuck he is in the area and has has a fast GPR

    SCOTT..............

  4. #4
    ABBOTT's Avatar
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    read this thread very carefully: This will help you.

    http://www.greenhulk.net/yamaha/view...806&highlight=

  5. #5
    Moderator RX951's Avatar
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    read this thread very carefully: This will help you.

    http://www.greenhulk.net/yamaha/view...806&highlight=
    ditto on dat !

  6. #6
    txgp1300r's Avatar
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    mine did that when chopping throttle at speed, i put on a 1200 2 bar r&d grate..solved it..no more suprises

  7. #7
    dhoad's Avatar
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    Thanks for the info re philip thread and the sponson stepping helped slightly with the ride.
    Scott, how do I get in touch with Chuck?
    Doug

  8. #8
    Moderator RX951's Avatar
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    When I chop the throttle at speed the ass off the boat rises,
    hhmmm.......

    Would 1200 grate help this?
    Doug, not sure....I've never ran an 800 grate to compare it to the 1200 grate. Maybe someone else can chime in......

  9. #9
    dhoad's Avatar
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    I think I was imagining things re 800 grate and rear of boat rising - I just was not accustomed to the 10 mph difference in top end speed, what I think I was noticing is the actual water and air resistance increase with new speeds. Also, would having the trim set for nose down attitude make any difference in things?

  10. #10
    Moderator RX951's Avatar
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    Also, would having the trim set for nose down attitude make any difference in things?
    Your trim should stay at neutral when making speed runs. Any adjustment up/down and you are obstructing/restricting the thrust some. the flow of water needs to be a sraight and smooth as possible.

    Someone will hopefully chime in about the characteristics of the 800 grate and 1200 grate vs. lift on both grates. the angle of the scoop and ramp on the 800 grate are different than the 1200 grate and I'm sure that affects your lift.

    Aslo the faster you go, the aerodynamics & hydrodynamics play more of a role.

    again, I personally can't say what each does comparably as I have never ran an 800 grate.

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