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  1. Member
    Join Date
    Jan 2005
    Location
    Red Oak Va.
    Posts
    10,597
    #21
    Is it rocking side to side or just dropping the nose. Side to side is chine walk and dropping the nose and porpoising is the prop losing bite and dropping the nose which means you either set too high prop to pad or the prop needs some work to help carry the bow.

  2. Member
    Join Date
    Sep 2016
    Location
    Ruma Ill
    Posts
    803
    #22
    He’s from Idaho I bet he is running high altitudes. Motor is most likely tired .

  3. Banned
    Join Date
    Sep 2017
    Location
    Idaho
    Posts
    125
    #23
    Nose bouncing up and down. I owned a triton and know what chine walking is. This isnt chine walking.

    Im in idaho and run high altitude. 3,100' mostly

  4. Pat Goff
    Join Date
    Jun 2004
    Location
    Seadrift TX
    Posts
    10,942
    #24
    High speed porpoising comes from your prop losing it's bite on the water. Lower your motor a bit and see if it goes away.
    Pat Goff

    Two degrees from center
    of nowhere.
    Smithwick TX.

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  5. Banned
    Join Date
    Sep 2017
    Location
    Idaho
    Posts
    125
    #25
    It does but i lose alot of rpms and speed

  6. Member lpugh's Avatar
    Join Date
    May 2009
    Location
    Sacramento Ca
    Posts
    5,164
    #26
    Quote Originally Posted by JamesfromID View Post
    I recently blew the motor i had on it which was a old mariner 175hp. With that motor, same prop, i was running 63 mph at 5600 rpms. The 200, same jackplate height, i ran 62mph at 5200. Raised the jackplate 1" and lost speed but gained rpms (57 @5600). Water pressure is at 12 psi right now. Prop is a 24 tempest. My elevation here is 3,000 ft above sea level. Holeshot isnt great. I carry about 30 lbs of tackle in the bow that i know isnt helping it lift which my boat has never lifted. I did have a 23 quicksilver prop that had no vent holes and it ran 61 @5400. I had it sent into have cup added and it fell on its face with 56 @ 5300. I tried a 23 tempest before i raised it and i had a better holeshot but lost 4 mph.

    Kinda stuck on where to go. If i drop to a 23, ill gain more rpms and i will most likely have to drop the jackplate to make up for higher rpms.

    Current setup.
    1987 skeeter 175-D
    1999 Mercury 200 EFI
    24P Tempest
    6" power lift manual jackplate
    Motor is in the top mounting hole.
    Prop has 3 medium prop plugs
    Water pressure 12psi
    Not sure pad height but i know it was at 3 and ive raised it a few times

    This is WOT
    3 in prop to pad is to high for that boat. Wont lift, water pressure will be low, RPM will be higher and top speed down and probably will have excessive chine walk and high rooster tail trimmed up as well as lot of torque steer
    I used to have one those years ago, I would highly recommend you run a 23 tempest at that elevation and use only one large plug, next drop the motor to 4 in prop to pad. The hole shot should be very good though you may have to lift just a little as it nose over to prevent blowout. Make a top speed run and slowly tweek the trim to find the sweet spot for max speed. It may be a little less than full trim up. Note the rpm and water pressure at this time (should have 15 plus PSI. Now lift the motor 1/2 inch and repeat. Is it better worse, also take note of steering effort right and left as well as water pressure. If better raise it 1/4 and repeat. keep doing this until you notice the Rpm goes up but the speed does not increase or goes down, When you reach that point drop the motor back down 1/4-3/8 in. also make sure the water pressure does not drop to less than 15 psi. You now have the correct engine height for your rig. Do not adjust engine height to correct high or low rpm, that is done prop pitch & cup, That boat will start chine walking with to much trim, find the best trim position by watching your gps and making slow minor changes to the trim until it is minimized. above about 65 mph it chine walk no matter the set up and will just have to master minor left tweeks in the steering to balance the boat. Do your setup and testing with normal load. Also loading the boat about 100 lbs heavier on the right side may reduce the chine walk as well, never run it heavier on the left side. At this point we must know accurate RPM (digital tach or at least verify accuracy of anolog and accurate speed (GPS). At 3000 ft I think you be hard pressed to exceed 65 mph.
    Now you are ready to call Mark Croxten and relay all info to him and he will get your prop near perfect for your rig. This is all assuming your motor is up to snuff
    Last edited by lpugh; 09-30-2018 at 10:00 PM.
    Thank You Leon Pugh

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