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Thread: K Plane Mounting

  1. #1
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    K Plane Mounting

    Putting a set of 280's on my 96 22 classic and leaning towards mounting them horizontal / flat. Does anyone have the dimensions for mounting them in this configuration.


    Thanks,

    Al

  2. #2
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    Do you plan on adding hydraulic steering sometime in the future?
    If you do, the cylinder end locations really need to be considered also.
    Why do it twice?
    George Carter
    Central Florida
    gcarter763@aol.com
    http://kineticocentralfl.com/


    “If you have to argue your science by using fraud, your science is not valid"
    Professor Ian Plimer, Adilaide and Melbourne Universities

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    Re

    Thanks for the response.

    Yes, my plans are to put a dual ram system in. Just may not be this go around unless I find a deal on something.

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    The flatter they are, the more outboard the rams will be, giving you more space for the steering rams someday.
    Cheers,
    Pismo
    1996 22 Classic
    Red with Stainless Windshield
    Stock Gen VI 502 Magnum MPI-415hp
    Stock Bravo I
    25" Mirage Plus
    74.5mph best @ 5050rpm GPS (Speedo said 80)
    27" Labbed Mirage Plus
    75.5mph best @ 4800rpm GPS (Speedo said 82)

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    Here's a look at mine. I haven't been able to fully test them yet to see how they compare to my old bennets which were mounted in the standard position. The outboard edge of the tab is about 1/4 above the bottom

    Steering rams did determine where I mounted mine. My preference would have been to mount them with the outboard edge of the tab 1/4" above the outer strake, but the rams interfered with the mounting plate.
    Attached Images Attached Images
    Why is faster never fast enough.

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    yeller nice looking drive that's a 22 right what are you running for power in that.I also am running a Blackhawk love the drive on my 18 . I was wondering if I should change my trim tabs to bigger what is the advantages to that over stock.And the 350 supercharge it like I did and never look back.

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    Yes, it's a 22. I was running a 496HO with procharger. It was an absolute handful and near impossible to get into the 70's with the bravo. 1st run with the BH and I hit 86 gps. The dual props are awesome. I can run the boat at top speed with no hands now if I want to.
    I cooked the 496 (not the S/C faults) and picked up a 502, also procharged. Last summer was the 1st time in almost 4yrs that I fired it up. It has an overheating problem, which I think is due to the heat exchanger. I didn't sort that out before our summer ended.
    I went with the longer tabs, because the boat really porpoises a lot with the BH. I'm hoping the longer tabs will mean I have to put less of them in the water to settle the boat down.
    Why is faster never fast enough.

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    yeller I had a 383 but sold that for a new 350 mpi and a whipple. assure help me with info on my set up great guy, It's been 2 years in the making of this but it will be done for this summer. Had to re do the stringers and transom to support the new power and the possibility of what the boat could do.It's like a car, can't put all this power too it and not build it to support it.they have dyno it at 550hp and with the drive will be crazy.I have a few picks I should put them up.

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    We're kind of derailing this thread. Start a new thread and post some pics
    Would love to see it.
    Why is faster never fast enough.

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    Is there an advantage mounting them horizontal ? My blackhawk came with 150s and I put 280 plates on. Big help with handling. Mine were mounted on angle with the hull. I no longer have the boat and can't help with dimensions.
    better to die on your feet, than live on your knees

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    Quote Originally Posted by smokediver View Post
    Is there an advantage mounting them horizontal ? My blackhawk came with 150s and I put 280 plates on. Big help with handling. Mine were mounted on angle with the hull. I no longer have the boat and can't help with dimensions.
    I am far from an expert, but based on what I was able to find out, the general rule is horizontal mounting is better for controlling chine walk and conventional mounting is better for load distribution.
    My big concern was porpoising. I couldn't find a difinitive answer on which way was better for porpoising, but I felt horizontal would scrub less speed with the tabs down. With a conventional mount, the forces created when the tabs are lowered fight each other and cause more drag (ie: reduced speed).

    Conventional.png

    With horizontal mounting the forces created work together and scrub less speed.

    Horizontal.png

    I'm hoping I will have the same porpoise control while minimizing the speed loss. That is my theory anyways.

    As an FYI: Dropping my old Bennetts could scrub as much as 15mph off my speed.
    Why is faster never fast enough.

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    Quote Originally Posted by yeller View Post
    I am far from an expert, but based on what I was able to find out, the general rule is horizontal mounting is better for controlling chine walk and conventional mounting is better for load distribution.
    My big concern was porpoising. I couldn't find a difinitive answer on which way was better for porpoising, but I felt horizontal would scrub less speed with the tabs down. With a conventional mount, the forces created when the tabs are lowered fight each other and cause more drag (ie: reduced speed).

    Conventional.png

    With horizontal mounting the forces created work together and scrub less speed.

    Horizontal.png

    I'm hoping I will have the same porpoise control while minimizing the speed loss. That is my theory anyways.

    As an FYI: Dropping my old Bennetts could scrub as much as 15mph off my speed.
    I agree, Changed to Horizontal on my 28zx was the best change I did. I plan on mounting my 280's on the Critter Horizontal!
    2000 28ZX Scorpion SOLD
    1979 Criterion
    1986 Z29

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    Here's my take on it, which is backed up by nothing more than experience and a little physics knowledge so I could still be wrong.

    I personally believe mounting them conventionally, parallel with the hull, is the way to go. I attached a couple pics of mine, one of which is right after I installed them so I didn't have a plate over the old Bennett holes, and one of them is recent but a pretty dark picture. I have the factory Ziegler dual ram hydraulic system, and dimensionally I had absolutely no issues mounting my 280 K-Planes conventionally. The K-Plane plates that mount on the transom are tapered on the sides, so when mounted conventionally, I believe you would have more space to work with mounting the rams.

    You are correct in saying that the forces fight each other when the tabs are down on a conventional setup. If you were to compare a setup of conventional tabs vs a setup of horizontal tabs both angled at 5˚ down, there would be more drag in the conventional setup. However, the conventional setup also offers more surface area than the horizontal setup, so less tab angle is needed to do the same thing that a horizontal setup would do. So you can use less tab on a conventional setup than you would have to with a horizontal setup- this is a huge plus because having a lot of tab down does increase the chance of them catching on the top of a wave in rough water and sending your bow toward the water.

    In addition, when you're going for top speed your trim tabs should be at neutral position anyway, not down to fight chine walk. Your arms are there to give gentle inputs to fight chine walk, if chine walk is an issue for your boat. At neutral position conventionally mounted, you have an extra 19" of boat length thanks to the trim tabs extending the boat, making your 22ft 6" long boat behave more like a 24ft boat. In a horizontally mounted setup, barely any water will actually touch the trim tabs due to them being higher up than the bottom of the boat and going straight out. Therefore, this setup offers less high speed stability than conventionally mounted, which extend the length of the boat and offer added protection from chine walk because they are at the same angle as the hull and offer side-to-side stability, if you see what I'm saying.
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    Donzi 22' Classic

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    I'd also expect that with traditional mounting, the water coming off the hull will be parallel to the tab surface, distributing the load evenly, as intended. Mounted horizontally, the outer edge of the tab will hit the water first, loading them with a twisting force. FWIW
    "I don't have time to get into it, but he went through a lot." -Pulp Fiction

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    I would mount them parallel with the bottom.

    Quote Originally Posted by RockyS18 View Post
    Here's my take on it, which is backed up by nothing more than experience and a little physics knowledge so I could still be wrong.

    I personally believe mounting them conventionally, parallel with the hull, is the way to go. I attached a couple pics of mine, one of which is right after I installed them so I didn't have a plate over the old Bennett holes, and one of them is recent but a pretty dark picture. I have the factory Ziegler dual ram hydraulic system, and dimensionally I had absolutely no issues mounting my 280 K-Planes conventionally. The K-Plane plates that mount on the transom are tapered on the sides, so when mounted conventionally, I believe you would have more space to work with mounting the rams.

    You are correct in saying that the forces fight each other when the tabs are down on a conventional setup. If you were to compare a setup of conventional tabs vs a setup of horizontal tabs both angled at 5˚ down, there would be more drag in the conventional setup. However, the conventional setup also offers more surface area than the horizontal setup, so less tab angle is needed to do the same thing that a horizontal setup would do. So you can use less tab on a conventional setup than you would have to with a horizontal setup- this is a huge plus because having a lot of tab down does increase the chance of them catching on the top of a wave in rough water and sending your bow toward the water.

    In addition, when you're going for top speed your trim tabs should be at neutral position anyway, not down to fight chine walk. Your arms are there to give gentle inputs to fight chine walk, if chine walk is an issue for your boat. At neutral position conventionally mounted, you have an extra 19" of boat length thanks to the trim tabs extending the boat, making your 22ft 6" long boat behave more like a 24ft boat. In a horizontally mounted setup, barely any water will actually touch the trim tabs due to them being higher up than the bottom of the boat and going straight out. Therefore, this setup offers less high speed stability than conventionally mounted, which extend the length of the boat and offer added protection from chine walk because they are at the same angle as the hull and offer side-to-side stability, if you see what I'm saying.
    I agree! Tabs should be an extension of the hull. You don't need much tab on these Donzis.
    Mounting them flat on such a short (22') boat could be an issue in rough water.
    Attached Images Attached Images
    Thanks, Patrick


    1996 22' Classic

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