flat bottom question

Discussion in 'Boat Modification Journal' started by Monsterkat11, Jul 31, 2008.

  1. Monsterkat11

    Monsterkat11 New Member

    i think i'm about to purchase a 16 foot flatbottom john boat. it's got the bench seats going across the boat, my question is, if i were to remove one of them to make more room, would it cause any structural damage to the boat? i'm not sure if they work as support too.

    like i said, only one of the benches in the middle of the boat

    and IF i shouldn't have any problems, how should i go about it? i'm sure they're riveted into the side of the boat.
  2. Katmandeux

    Katmandeux New Member

    Checotah, Oklahoma
    You won't get a unanimous opinion on that...some say yay, some say nay.

    I say no, leave the seat where it is. If you just gotta have that seat gone, trade boats, and get one that was built and engineered to be structurally sound without the center seat. Alumacraft and SeaArk both have no center seat (ncs) models, and I'm sure there are others.

  3. Mark J

    Mark J New Member

    Four Oaks, NC
    Some of us that say nay have seen the effects on aluminum with a boat left just as it came from the factory.
    I've seen the cracks caused by the torque of the motor up around the center console. It's caused by FLEXING.
    Bobpaul has seen them further up then that towards the bow.
    These are boats left alone.

    These kind of questions generally boil down not so much the opinions people give but ultimately what you want and what you are willing to risk.

    If its a 16 footer with a 9.9 on it I'd probally chance it sight unseen.
    It's the motor that will sink it.

    EXTREME lateral pressures are exerted on boat hulls by outboards.
    You take enough structure out of one and still has a larger motor on it, you can twist that sucker like a pretzel real quick. Remember the keyword above.
    FLEXING. You want some flex in some places which adds to the strength of the overall structure. Other places need to be rigid.
    Like a skyscraper. It's foundation is rigid but it's allowed to sway with the wind. If it didnt it would break.

    My final comment.
    If you are mechanically inclined and have some degree of what structural is and is not and you know how to adequately work with the material I MIGHT tinker around a bit.
    The biggest problem you face is flexing, hull failure, and the lifespan of a hull drasticly cut.
  4. roadkill636

    roadkill636 New Member

    warrenton misso
    a friend of mine had a 16' monark rivited, mid 1970s, that he removed he middle bench, it really opened it up
    he ran a merc 40hp on it for over 15 years,no real problems
  5. cantstopgrandma

    cantstopgrandma New Member

    I probably wouldn't. When I was looking at jon boats i looked at alumacraft, and their models with no center seat actually have a longer front deck and weigh more than the models with a center seat. I'm guessing this all has to do with trying to make up for the lack of support with no seat in the middle. My uncles polar kraft has had the middle seat removed for over 20 yeras and has been thru the ringer with no problems, however if you look at that boat, just from the way the floor and sides are braced, i'd have to say the seat didn't add that much support anyways (but i'm no structural or maritime engineer). Thats a really beefy boat though, and most boats these days dont seem to be built that heavy. The question here is how brave are you? I spent a lot of money (to me anyways) when i bought my boat, i'm not willing to risk messing it up on a chance it MIGHT be OK.
  6. Monsterkat11

    Monsterkat11 New Member

    i've been reading up a bit, now i know if i have the guts to do it, i'll have to add extra support to make up for the removal. i'll just have to see what the boat looks like i guess!

    i mean, come on, it's a 16 foot flat bottom, even if there is a few bench seats, i'm sure there will be PLEEEENTY of room between them
  7. germanmudfish

    germanmudfish New Member

    Gray, GA
    Grizzly....Check into some of the conversions done on aluminum jon boats. They remove seats, add flooring, etc. Making them bass boats. Why not get a bass boat? Do some research though, don't want to lose a brother to the water.
  8. jtrew

    jtrew New Member

    Little Rock, AR
    Probably going to depend on the individual boat. I was given an aluminum speedboat with a modified V-bottom; the kind that has the top covered with aluminum except for two sections for passengers. I removed the entire top, floor, and everything else inside, leaving just the bottom hull. It still seemed to be very solid, with little or no flexing. Of course, it originally had a 60 hp motor on it, and I was operating it with a 15 hp outboard, mainly to see if the small motor would plane the hull ok. (It did.)
  9. 1mickymoo

    1mickymoo New Member

    Edgerton, Kansas
    I removed the center seat from my 16.5 Monark, but, I added support by flooring screwed into the ribs, as well as up the sides. I have had no real problems, lots more room, it does change your boat though, most bench seats are actually flotation devces also. Good luck.
  10. CountryHart

    CountryHart New Member

    My dad bought a new alweld that had seats. He had the dealer remove them and add ribs in their place. He runs an elec. shift 25 merc and hasn't ever had any problems with it. I myself like an open boat so i can move around.
  11. riddleofsteel

    riddleofsteel New Member

    I have an Alumacraft 1648 NCS (no center seat).


    Right after I got it I added closed cell foam between the bottom ribs and installed a deck made of diamond tread aluminum screwed down to the ribs with stainless screws. I love the open design and I honestly don't think I would enjoy fishing a boat with a center seat after using mine for several years. The raised front deck is perfect for throwing a net, flounder gigging, throwing a bass lure or fly fishing.
    I am currently running a 25 HP Honda tiller on it and it steps along pretty well. In rough water it is a little rough riding but I would not trade its shallow draft and stability for a smoother ride.