Thread: Prop to Pad

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  1. #1
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    Question Prop to Pad

    Are the prop to pad measurements the same on a boat with no jack plate? Also, does the distance change in the setback of the jackplate, like from a 4" to a 10"

  2. Member
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    #2
    The only thing that the jackplate has to do with P2P is that's normally how you adjust it. The setback can affect the P2P depending on the angle of the transom.

  3. Banned
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    #3
    Their is a sticky at the top of the page about how to do it correctly. Distance between the motor and the transom does not change the p2p measurement. Moving the motor back further does two things. Changes the balance point of the hull and puts the motor in rise of water behind the boat. Most hulls the rise dosen't matter but some fast hulls that run the prop at the surface it matters.

  4. Member
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    #4
    Prop to pad is usually lower without a jack plate normally 4.25" under pad on most boats. Running higher than that usually causes prop to slip bad unless you have a plate.
    Last edited by mdtritn21; 04-27-2020 at 08:44 PM.

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    #5
    If you run a jack plate on your boat you can normally run higher prop to pad than you can just bolting the motor to the transom. The set back allows the motor to run in the swell behind the boat which is higher than the bottom of the hull when the boat is moving at speed. Too much set back can cause you to get behind the swell which causes the boat to slow down just like having the motor bolted to the transom.
    Last edited by mdtritn21; 04-27-2020 at 08:50 PM.

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    #6
    Adding to all this, what exactly dictates the set back distance of a jack plate. How do you decide the distance between a 4" or a 10". Or is it a preference thing, just get what you want and set it all up accordingly. I fish a lot of shallow water and I always found having the motor set back gave the rear fishing deck more room with the motor trimed up on my glass boats. I haven't yet installed one on my Tracker 185 yet, just was questioning the aspect of the setback on these tin boats before I do. The boat runs fine, I just want the extra room at the back. Extra room is for a friend in a wheel chair.
    Last edited by Crappie Bob; 05-02-2020 at 07:02 PM.

  7. Member
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    #7
    I'd put a 6" at most for set back only but it may not run any higher prop to pad than it does now since that boat doesn't have a real pad.

  8. Member
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    #8
    Quote Originally Posted by Crappie Bob View Post
    Adding to all this, what exactly dictates the set back distance of a jack plate. How do you decide the distance between a 4" or a 10". Or is it a preference thing, just get what you want and set it all up accordingly. I fish a lot of shallow water and I always found having the motor set back gave the rear fishing deck more room with the motor trimed up on my glass boats. I haven't yet installed one on my Tracker 185 yet, just was questioning the aspect of the setback on these tin boats before I do. The boat runs fine, I just want the extra room at the back. Extra room is for a friend in a wheel chair.
    Bob,
    The basic theory on function of a JP is to place the motor in a cleaner water area coming out from under your hull. I am sure you know that water coming out from under the hull closer to the transom is highly disturbed and aerated causing the prop not to bit into it pushing you forward, which is called prop slip. However, JP changes fulcrum point of your boat to motor, which puts greater stress onto your transom and the ability to give you bow lift. I believe that your hull is mostly flat with a modified v closer to transom and a short step just infront of transom. The idea of the step is to give you static break and some transom lift, somewhat like trim tabs on large boats. I believe that your P to P should be measured from bottom of that mod V to center of your prop shaft after the boat bottom and motor anti cavitation plate have been place level to the floor or ground, which yours was set from factory in the 4-4.5" range.
    I have had this discussion with another member with a G3 boat with 90hp motor, and in the end, he found out that the manufacturer did not recommend using a JP, which left him with the only choice of moving the motor up 1 hole or maybe 2, while testing different props.
    If you are happy with your performance and handling, I would leave it alone, however, it is your choice to make once you call your manufacturer to ask if you can use a JP.
    Be well and be safe.
    Last edited by digthemup; 05-10-2020 at 10:41 AM.

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    #9
    What boat do you have and what motor?
    2011 Nitro Z7
    2011 150 Mercury Optimax

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    #10
    Quote Originally Posted by zprice7 View Post
    What boat do you have and what motor?

    Tracker 185 XT Pro - 90HP Mercury 2 Stroke

  11. Member
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    #11
    Quote Originally Posted by Crappie Bob View Post
    Tracker 185 XT Pro - 90HP Mercury 2 Stroke
    I would try a 4”-6” manual jack plate but no more than 6”. This will set your motor back in cleaner water.
    If you do choose to put a jack plate on then it will probably change your prop to pad measurement. You could use the motor holes to try to even it out if the jack plate does raise your motor a bit even when it is placed in the same holes as it was on the transom.
    2011 Nitro Z7
    2011 150 Mercury Optimax