jon boat - effect of taller sides?

Discussion in 'Boat Design' started by gruntled, Jun 27, 2020.

  1. gruntled
    Joined: Jun 2020
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    Location: Fl

    gruntled New Member

    If one were to take a simple flat bottom jon boat design - like this one from the Kentucky critter cops - Kentucky Department of Fish & Wildlife Plans for Building a Flat Bottomed Boat https://fw.ky.gov/Kentucky-Afield/Pages/Plans-for-Building-a-Flat-Bottomed-Boat.aspx - that was designed with ~12" sides, and instead built it using taller sides - say, 15"-18" or even 24" sides?

    Would this simply add load capacity but increase the amount of drag as the load increased and it sat lower in the water? What would happen with stability? Would it still be pole-able, paddle-able, or electric-motor-able ?

    I ask 'cause I've watched their build video on youtube (dangerous, I know) and this seems like it will fit in my budget and skill set, but I've also watched 'em fishing from it and those sides were awful close to the water for my taste/use (they are relatively skinny guys)...
     
  2. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    Gruntled, Best advice is do not even think of building this boat. It is a poor example of a boat. It would not be safe in any water other than a calm pond. There are many free designs on the internet that could make a reasonably serviceable boat. Shop around until you find something better than this ill conceived tub.

    It is surprising that the Kentucky Wild Life commission would dare allow this kind of thing to be posted under their name. I can see liability suits a plenty as a result of this design.

    The boat and occupant and whatever gear you included , could have, for example, a total weight of about 200 pounds. At that total weight it would sink into the water about two inches. In that case the front end of the boat (the bow transom) would be only one inch above the water surface. The boat would plow unmercifully if you moved it with either oars or a small motor. It will be a miserable boat to paddle or row and a dangerous one if powered by a motor.

    Tell us how the boat would be used. With a motor? Propelled by oars or perhaps poled? In what kind of water will it be used....lake, pond, river, Biscayne Bay or.......???

    Sorry about the copious criticism. I suspect that some of the other forum members will agree.
     
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  3. gruntled
    Joined: Jun 2020
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    Location: Fl

    gruntled New Member

    Thanks. I'm in N Florida so basically the local rivers (3 ramps on the Santa Fe are only 20 min from the house) and possibly over to the gulf coast near cedar key to fish around the oyster beds, etc - so again, basically flat and glass like.

    But my question in general stands - lets say instead of the KY boat, I got the plans from unclejohns. What effect would higher/taller gunnels have?
     
  4. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    Freeboard is a slightly over-rated thing, in small boat safety, light boats can bob pretty well without high "walls", to "keep the water out". Some people actually equate freeboard with a safe boat, when of course the relationship is a lot more complex than that. A better guide would probably be not so much how much hull is projecting above water, but how much of the total depth of the hull, is actually underwater, in relation to the overall depth. If that is high, then a little more freeboard is likely desirable.
     
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  5. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    Some people believe high winds are a greater threat to smaller, lighter boats, than the waves they generate, there is some truth to that, or can be, so there is a definite law of diminishing returns to increasing the amount of freeboard.
     
  6. messabout
    Joined: Jan 2006
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    Location: Lakeland Fl USA

    messabout Senior Member

    Gruntled, The locations where you might use your boat is not a healthy for a small boat like the one you have suggested. The Santa Fe river is a waterway habitually and continuously abused by ill born madmen. Take a look at this video:


    Cedar key is a delightful place but has a lot of big boat activity. You might want to cross the half mile or so distance to Atsena Otie key. There is a nice beach there that has good shellfish digging, at low tide. The fishing is pretty good there too. To get there in the Kentucky "boat" would be tempting fate.

    I urge you to consider a much different, easy to build, boat that does not even faintly resemble the one that you have suggested. There are many free designs on the internet. Some of them are far better and safer than the one you are considering.

    You could raise the sides without adding much of a problem. As Mr E says, too much sheer height can create its own problems. Not the least of which is that your oars would need to be longer. The transom on the Kentucky thing needs to have some slope if a motor is to be used. The size of the motor must to be very small because of its' the weight......unless you raised the height of the transom and the sides.

    The video of the build has the guys using clear one by twelve planks. Good luck finding boards of that size that are not scandalously expensive.
     

  7. Mr Efficiency
    Joined: Oct 2010
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    Location: Australia

    Mr Efficiency Senior Member

    absolutely agree with messabout, than the rudimentary "jon boat" is not suited for anything other than sheltered backwaters, which I expect must users adhere to. Even in still waters, a little common sense has to kick in, to keep the boat from tipping too far, to the point of water ingress, but that is a matter of not overloading the boat, and having passengers careless about where they position themselves. It really is, just common sense.
     
    Last edited: Jun 29, 2020
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