Requesting Small Sternwheeler hull design and analysis help

Discussion in 'Boat Design' started by phrogjlf@yahoo, Nov 18, 2014.

  1. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    If I could take the Panga from lewisboats, cut a low, flat deck-line, average the chines like the orange lines below, then get the stern wide enough for the sponsons and paddle-wheels, and maintain that kind of taper to the transom, with that shallow draft. I think I'd be done...

    [​IMG]
     
  2. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    I admit, she's cut too low. Already mentioned my lack of skill at even Windows Paint. I figure more like 20" from keel to the flat deck, then use combing to give me better water resistance above the deck. If I can get a 6 ft notch, between 9" wide, 36" long wheel-arms/sponsons, that should be just about perfect.
     
  3. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    Can this be done?

    I know, it doesn't quite work like that..., but, can something close this be done?
    It needs more prow, but it's beyond my limited capability to do much better.

    [​IMG]

    Did I mention my crappy Windows Paint incapability... :D

    Keep the shallow water of the Pango hull and keel, translate the waterline onto a broad jon-boat? Maintain the idea in planks from plywood?
     
  4. WindRaf
    Joined: Oct 2014
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    Location: Italy

    WindRaf Senior Member

    progolf @ yahoo. progolf @ yahoo. is offline
    JL Fruscia

    If you look closely at a boat with the submerged stern when riding at low speed, you will see that the water trail is very agitated, as if to boil.
    This means that a good part of the engine power is not used to push the boat, but for boiling the sea.
    If you have an electric engine the speed will be lower and the batteries will discharge very quickly.
    If you want to have a normale engine 20-25 hp on a boat of 20 feet, then to hold this power the boat needs the submerged stern.
    In short, a boat with hull speed is incompatible with a boat with electric propulsion.
    You have to choose, I think.
     
  5. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    I think it's the keel line that makes the difference. The keel bellies out a bit, under the middle of the Pango, then the bottom panels bow up in a gentle curve. I know I screwed up the bow, but I already said I'm no artist. I'll work on it some more, to get the bow end of the waterline to look right.

    If you look at the lateral 50/50 of the Pango. you can see that same low dead-rise I've been trying to describe. If you look at both the jon boat and the Pango, you can see how the Pango curved up and out aft, rather than maintaining a straight line.
     
  6. WindRaf
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    WindRaf Senior Member

    phrogjlf@yahoo. phrogjlf@yahoo.
    JL Frusha


    Yes I see,
    but your designe now is not able to support 20 hp.


    here my solution:

    VJ plan.jpg

    VJ assonometria.jpg
     
  7. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    Can I put the Pango Keel line, on the Jon Boat hull, to get what I'm after...?

    [​IMG]
     
  8. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    Can it do something close to this...?

    I know stuff is off, but I don't know exactly how to fix it.

    This is about as close as I can do, with Windows Paint, and borrowed images, to show what I think should work...

    [​IMG]
     
    Last edited: Dec 8, 2014
  9. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    Not trying to support 20 HP. This is a low and slow. Not intended to do anything fast. I think the equivalent thrust:HP was something like 6 HP, but I may be able to fix that to a higher number, with a different electric configuration, like driving outboard lower-units with electric motors, instead of trying to cram some ungodly number of trolling motors in place, especially the way the water divides along the keel.

    I still need width. I know the outward angle of the gunwales aids stability, both with off-center loading (boarding) and with turning. Rather than a multi-chine, a simpler 4-plank, built on frames will be within my ability, using th 5/8" plywood. I can build the frames on a strongback, clamp the plywood and slowly work from one end to the other, one frame at a time.

    The transom and the bow-plate should still look roughly the same as the original wide jon-boat, but the water-line has moved down, to clear the transom.

    Sorry for my crappy Win-Paint, but it's about as good as I'm capable of...
     
  10. WindRaf
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    WindRaf Senior Member

    did you read my post No. 126?
    That solution is:
    - V bottom, so you get up from the mud
    - Flat bottom behind, which is the best for Whell
    - Outputs Stern are always clean
    - Lateral stability is good so you can make the cabin above
    - When you go with the electric sistem the resistances are minimal
    - When you go with the 20 hp gasoline the stern is lowered a bit 'and becomes a carrier for the power.
     
  11. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    Looks great! I missed the outline on the thumbnail, so I misinterpreted the shape... Accidentally grabbed the old glasses, instead of my new ones. Big difference...
     
  12. lewisboats
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    lewisboats Obsessed Member

    WindRaf has a novel, and to my mind, pretty good solution although I might go with a bit less deadrise or perhaps a very small flat in the middle to reduce the draft by an inch or two. A flat of 8-10" or so wide wouldn't cause much if any suction and you can easily rock it either way to break any that might develop. The flat sections aft will help support weight with minimal submersion while allowing the wheel to get as much bite in the water as possible. Yes... this is a good solution and probably better than I would have come up with.
     
  13. WindRaf
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    WindRaf Senior Member

    for enlarge my immages click on with the right, an then click open in a new window
     
  14. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    I know something I was doing wrong. Just caught it. I was stretching the scale of the waterline to the length of the hull, not matching waterlines. Stupid mistake, but I'm learning... :D
     

  15. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    Does this look better?

    Resized the Pango keel and waterline to the modified jon-boat waterline.

    If I've learned anything, it should start looking closer to the hull plan and water footprint, as I've tried to show it.

    [​IMG]

    I still think your 'V' is too deep and narrow. A broad, flatter angle will displace more evenly and raise the keel. If it is stretched all the way across the hull, we get rid of the flats that could prevent rocking loose from the mud. Not trying to lose the buoyancy, just the flat spots, at the edges of the hull. When I deck her, and put in combing, that area is part of what will be foam-filled.
     
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