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Thread: Advice on a PAD

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  1. #1
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    Question Advice on a PAD

    I talked to Glenn Hopkins and his advice for me either to try extending my trim tabs across the length of the transom and make them adjustable or welding a pad to the bottom of the boat. He said make it 5 ft in length and about 14 inches in width. I'm curious to know could I make it 10.5 inches in width? or even 12 inches possibly?
    10.5 would be better for the way the hull comes to a V at the stern and the chimes are so dang close together.
    I would think the narrower the pad the faster it would go but harder to control correct?
    would my 50 tohatsu have a hard time getting the boat onto a 10.5 inch pad??

    What advice can yall give me? I hadn't talked to Glenn in a couple of days and been brain storming this.

    Thanks
    Chris

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    Team Member bad news racing's Avatar
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    Chris , the smaller the pad the more horse powe it takes to get it up and keep it there

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    Quote Originally Posted by bad news racing View Post
    Chris , the smaller the pad the more horse powe it takes to get it up and keep it there
    I agree with the horse power to a certain degree on keeping it on the pad. my boat has a 14" pad with a 40 hp. With a regular prop without trim you would have to ride it through the bouncing until it was on the pad, added a hydraulic jack plate came up on engine 2.5 inches
    rides good from 35 mph to 44 mph any slower it wants to fall off pad. With chopper prop at 40 mph it want to fall off pad at 52 its on pad and holding.I think I could come up more on the motor but need to get used of driving this boat first.

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    Quote Originally Posted by bad news racing View Post
    Chris , the smaller the pad the more horse powe it takes to get it up and keep it there

    what is your advice then go with 14 inches?

  5. #5
    Administrator Ron Hill's Avatar
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    Default Transom View Photo...

    Bottom Line: We have 15 HP motors with 36-39" pads running 50 MPH. Old Hydrostreams ran a 4 inch pad with 150 HP. But with a 40 HP, 30 inch pad would be better than a 14" pad. 10 inch is a "NO NO"...

    Boats have four stages: 1. Float 2. Plow 3. Plane 4. Fly For speed, you want to fly!

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    Quote Originally Posted by Ron Hill View Post
    Bottom Line: We have 15 HP motors with 36-39" pads running 50 MPH. Old Hydrostreams ran a 4 inch pad with 150 HP. But with a 40 HP, 30 inch pad would be better than a 14" pad. 10 inch is a "NO NO"...

    Boats have four stages: 1. Float 2. Plow 3. Plane 4. Fly For speed, you want to fly!

    Thanks Ron, it's better to ask all the questions now before i get down the road and have a problem. Just gonna have to do more figuring this weekend and may just have to make a 14 inch work or even a spec more

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    Question

    Haven't done the pad yet but I have all my material and found a guy couple days ago with a brake to bend my sheet into a channel and well I was talking to someone last night I think his boat is 15 ft in length and he said his pad is about 12 ft in length under the boat.
    Do you think i'm gonna have a problem with this pad being just 5ft in length or should it be longer? I hope not because I have everything setup and ready to do it but am having some second thoughts here on the length of the pad going forward. My pad is currently 5 ft in length.

    Just like a little more advice would this length be ok?

    Thanks
    Chris

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    Team Member Smokin' Joe's Avatar
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    My 14.5' Allison weighs about 350 lb and runs about 42 mph with a 1983 Johnson 35,
    after a lot of triclky prop work. the pad width is 8". A wider pad would not be faster,
    the boat already runs too wet because 35 hp is not enough to get it on the pad. I
    would not widen the pad, I'd add lift strakes off the pad designed to make the flow more two
    dimensional. that would lift the boat at the pad.

    I think that there is no rule from hydrodynamics that tells us what is an optimal pad
    width. Were there such a rule then I would have been able to derive it mathematically.

    The Professor

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    Team Member Smokin' Joe's Avatar
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    Not necessarily. If you stop and think you'll realize there must be a limit,
    because a pad V is faster than a flat bottom, all other things being equal.
    On the 13' Allison with OMC 75 an 8" pad was too wide, the boat ran deeper at the
    transom. With a 7" pad the boat gained speed and turning ability. The original pad width was
    5.5". The problem with an 8" pad is that it was too deep, that caused the extra drag that allowed
    the boat to sink at the transom. The pad was too deep because the Allison is built with just
    the right degree of deadrise to allow the boat to bank and turn well. Look at an old 14' Allison
    'with a 7" pad. You don't want the pad to be any deeper than that. Otherwise, you're dragging
    extra water.

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    AeroMarine Research Jimboat's Avatar
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    Quote Originally Posted by chris3298 View Post
    I'm curious to know could I make it 10.5 inches in width? or even 12 inches possibly? I would think the narrower the pad the faster it would go but harder to control correct? would my 50 tohatsu have a hard time getting the boat onto a 10.5 inch pad?
    The size of the pad should be sufficient to provide greater portion of dynamic lift of the hull. A wider pad is more efficient, but also harder ride. Optimum width and length are sized based on hull weight, power and dynamic balance.

    Article on Vee-pad design

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