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  1. #1
    Cadet
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    Default Motor Size For Jon Boat

    I have an 11ft boat that is kind of like a Jon boat. The bottom flat and the width is 40" the sides are 15". The boat weighs 100lbs and is rated for 700lbs capacity.

    My question is how heavy can I go with the motor. I'm looking at a 85lb 9.8hp Nissan 4 stroke but is that too heavy? I weigh 180lbs. I want the 9.8hp if it is safe but if it is not I'll have to go with a 6hp 4 stroke that weighs 55lbs.

    Keep in mind that saftey is my number one concern.

    So is the 9.8hp 85lb motor too much???

    Thanks.

    GOB

  2. #2
    Lieutenant Commander arks's Avatar
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    Default Re: Motor Size For Jon Boat

    What is the maximum rated HP on the capacity plate? You should NEVER exceed that number.
    As far as the motor weight, with a boat that small lighter is always better. If you hang 85 pounds off the stern then you'll definitely have to add some ballast at the bow to compensate.

    For comparison purposes, my old 10' flat-bottom Jon had a maximim HP rating of 5HP. I installed a good running 4HP Johnson 2 stroke and discovered that it would barely plane, and only if I sat towards the bow. That motor only weighed maybe 40 pounds. Oh, and I weigh 180, too.

    here's the setup I'm talking about:


    "Winter Dream"
    Silverton 34C
    White/Green

    Wellcraft 23 Nova XL

    Lowe 1448 BigJon
    w/Evinrude 25HP

  3. #3
    Honorary Moderator Emeritus tashasdaddy's Avatar
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    Default Re: Motor Size For Jon Boat

    these boats were not designed to go fast, it is probably not rated for more than a 6 hp.
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  4. #4
    Petty Officer 1st Class jspringator's Avatar
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    Default Re: Motor Size For Jon Boat

    If you can't find the plate, contact the manufacturer. That's what I had to do with my PolarKraft.

    Keep in mind that a 2 stroke will be lighter for a given hp than a 4 stroke. If you aren't happy with the boat's speed, you won't be happy with the boat. Keep that in mind before you spend any more money on the outfit.
    1989 Bayliner Ciera 2150, 5.8L OMC;
    1975 Johnson 6;
    Saturn SD365, 2009 Yamaha 15 2 stroke.

  5. #5
    Chief Petty Officer
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    Default Re: Motor Size For Jon Boat

    Hard to say with the little info given. A 40" botom you say?? That's an odd size in a jon. Is it glass, plastic or aluminum? A pic /model of the boat would help. Having said that, I'd guess that a 85# 10 hp is too much for an 11' boat. She's really going to squat at rest. I'd look for a 5-8hp 2 stroke in the 45-60# range. FWIW, my 85' Johnson 6 hp weighs in @ 56# and will push an old Sears 12' John to the point it will chine walk in the turns! It's a wild ride! Conversly a 66# 5 hp 4 stroke seemed to really bog the boat down with weight.
    I'd start @ 5 hp and work up.
    Borrowing/test running should be a MUST If you don't have the factory info on HP rating, . Otherwise mistakes can be costly and dangerous.


    ps for arks: I've owned two of those identical Johnsons (with that funky angled gearcase.) Never got mine to plane anything either. Those motors (while smooth and dependable) were geared and propped LOW for trolling. My 3.3 Mariner and newer 4hp Johnson would run circles around them.

  6. #6
    Lieutenant Commander arks's Avatar
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    Default Re: Motor Size For Jon Boat

    Quote Originally Posted by Wee Hooker View Post
    ps for arks: I've owned two of those identical Johnsons (with that funky angled gearcase.) Never got mine to plane anything either. Those motors (while smooth and dependable) were geared and propped LOW for trolling. My 3.3 Mariner and newer 4hp Johnson would run circles around them.
    Thanks for that info. It was marketed as a "weedless" gearcase, but it still likes to collect 'em....
    BTW, I still have that motor- any idea what it's worth?
    "Winter Dream"
    Silverton 34C
    White/Green

    Wellcraft 23 Nova XL

    Lowe 1448 BigJon
    w/Evinrude 25HP

  7. #7
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    Default Re: Motor Size For Jon Boat

    [QUOTE=Wee Hooker;1948153]Hard to say with the little info given. A 40" botom you say?? That's an odd size in a jon. Is it glass, plastic or aluminum? A pic /model of the boat would help.


    I my original post I indicated that it is "like" a jon boat. I stated that as I was trying to give readers as close a discription to relate to.

    This particular aluminum boat used to be manufactured in British Columbia, Canada for stillwater lake fishing particularly for flyfisherman. The true 40" bottom is to allow 2 adults stability when casting while fly fishing, which it does easliy. I'm thinking of purchasing a 6hp 4stroke weighing in at 55lbs but any other suggestions would be appreciated. I like the 4stroke for it's ease of operation(no oil mixing, cheaper to run and better for the ecology) .

    John

  8. #8
    Captain mthieme's Avatar
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    Default Re: Motor Size For Jon Boat

    I have seen many 12'ers with 7.5 hp.

    Nothing is so broken that Government can't make it worse.

  9. #9
    Chief Petty Officer
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    Default Re: Motor Size For Jon Boat

    "Thanks for that info. It was marketed as a "weedless" gearcase, but it still likes to collect 'em....
    BTW, I still have that motor- any idea what it's worth?"


    Yea, they actually marketed a folding weedless 4 hp for a short time! Odd.

    Anyway great little motor for fishing. Mine would idle so low you could watch the prop turn! If it weren't for the PITA direct drive feature, I'd still own one (or both.)
    FWIW, Sold my 78' version in good condition for $150. Sold my 82' (if memory serves ) in VG condition for $225. Your's looks clean and latter so I'm guessing $250 would be fair.
    hth

  10. #10

    Default Re: Motor Size For Jon Boat

    I have a 12 foot narrow shallow jon with a 71 johnson 9.5 and that thing will flat move on top of the water.

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