16' Steel Jon Boat

Discussion in 'Metal Boat Building' started by bholly, May 4, 2015.

  1. yofish

    yofish Previous Member

    How long is your brake?
     
  2. yofish

    yofish Previous Member

    So here we have your jonboat: 16' loa X 5' w X 2' h (4' w on the chines). The pics show lines, 3D view and plate developments with respective square footage per each. This a rough sketch that took all of 20 mins in ProSurf and is no way a finished plan but serves to give you some idea of the relationships between the elements you are dealing with. Get your charts out at work to calculate the various weights produced by each plate selection.

    for example: if using 1/8" AL plate = 227 lbs., 16 ga. steel = 328.7 lbs. I can't imagine making this out of material that is less than 1/16" (16 ga.) thick but I have no experience so what do I know? This does give you a perspective on what Tansl was getting at.

    You do not need to have anyone design a jonboat for you, you can do it yourself. They are about the simplest thing you could ever build; no naval architect needed.
     

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  3. WindRaf
    Joined: Oct 2014
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    WindRaf Senior Member

    my idea

    steel 16' W-Selva.png




    assonometria steel 16' W.png
     
  4. Mr Efficiency
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    Mr Efficiency Senior Member

    Hey WindRaf, your little boat has the Selva, how do they compare with other brands, do you know ?
     
  5. WindRaf
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    WindRaf Senior Member

  6. WindRaf
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    WindRaf Senior Member

  7. Mr Efficiency
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    Mr Efficiency Senior Member

    Thanks for that, WindRAF, but are they as good as the major brands ?
     
  8. WindRaf
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    WindRaf Senior Member

    Mr. Efficiency, as with all brands, there are fans and no fans.
     
  9. WindRaf
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    WindRaf Senior Member

    at any rate, Selva has the partnership with Yamaha: the two engines have most of the components in common
     
  10. Mr Efficiency
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    Mr Efficiency Senior Member

    OK, I see the 4 strokes are Yamaha engines, at least. Thanks.
     
  11. bholly
    Joined: May 2015
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    bholly Junior Member

    10'. I think I'll make a sketch and post it up. Y'all can let me know what you think.
     
  12. yofish

    yofish Previous Member

    With the brake, you can save yourself some weight and a lot of welding by pressing V strakes in both the bottom and sides. You can only do this on the bottom up to where it begins to climb from the baseline. Most all gauge AL jonboats (and a lot of other styles) are made this way.

    Your biggest challenge from a longevity standpoint is how the welding is done. Not from a structural standpoint but more from the rusting of frames that can't be continuously welded on both sides. Even a good thick epoxy like Ameron 235, which floods under and protects tight framing, will break down over time. Once rust sets in these sorts of places, it's basically over especially if they are under water a lot. By over, I mean that it will be an issue till the end-of-life as there is no real economical way to end it so one if left with good old scrape-n-paint. This also brings up the fact that realistically, you are not going to be able to put strakes on the bottom as stiffeners. This makes pressing in strakes even more attractive.
     
  13. waikikin
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    waikikin Senior Member

    Hi Bholly, Yofish,
    Sounds like a good scheme, the pressing holds the plate form like a crease?
    Thinking out loud- the framing could be buoyancy tanks & seal welded(this could aleviate frame/plating rust issue- at the size 16' level floatation would be a very good idea. A vessel such as this could easy have 2 x longtitudinal tanks that form seating & maybe across bow & stern also, some nice rectangular hollow section for a gunnel/rub rail..... sure it's going to add some weight but already accept that she's a heavy girl.

    Jeff
     
  14. yofish

    yofish Previous Member

    Jeff, one of the problems with what you suggest is that it will add A LOT of weight, perhaps enough to be a deal breaker. Also, there is the issue of separating the boat with a 'dam' across the middle, say, for seating. Probably better to use foam and some lighter structure to secure it. In this pic one sees typical pressed strakes in typical gauge AL jon boat. These are U shaped, mine is V. I should say mine, that I gave to my kid in Fairbanks recently.

    One does see a lot of work boats as Gonzo pointed out made of steel and they all have bow and stern welded-in floatation. Typically they have nothing else inside save tie-ups to be as clean and user friendly as they can be.
     

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  15. WindRaf
    Joined: Oct 2014
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    WindRaf Senior Member

    The boat that I drew up, I know it is not a 'Jon Boat', but a modern semi displacement 16' long, designed for steel. His final displacement is 0.6 tons, and the hull can weigh 350 kg; this means that there is no need to make a building with thin sheets, but normal thickness of 3 mm for the bottom up to the step, and 2 mm for the high side.
    It is a real modern little boat thought to last long.
     
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