Requesting Small Sternwheeler hull design and analysis help

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

  1. gonzo
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    gonzo Senior Member

    Each time you reduce the speed, you increase the torque by the same ratio. The second transmission will not be capable of absorbing the torque. Your insistence of trivializing good engineering practice can only end in disaster. The laws of physics don't care if this is your dream.
     
  2. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    That would depend on the 2nd transmission. The Dynamax units would be overkill and far excess of the necessary weight, but they would certainly handle the output of this electric lawnmower.

    I've seen, and it has been suggested, to use a gear-reduction, followed by a belt-reduction, followed by a chain reduction, to drive a paddlewheel, all adapted from stuff not intended to handle the torque developed, but it worked, or it wouldn't have been suggested. That's 3, different, jury-rigged drives, back-to-back, but it was suggested and has been done.

    To use the method I described earlier, for the dual rear-wheel design, I'd put something like a trailer spindle on the outboard wheel-arms, put in a central stub arm to mount the lawnmower axle and hold up a pair of pillow-block bearings, such as those on split-shaft pickups, for the inboard end of each paddlewheel-shaft. That supports and stabilzes both sides of the wheel. Build each wheel with the spokes at the outboard end and just inboard of where the track will go. Mount a Y brace, so the paddlewheel shaft passes through it without it being mounted to the shaft, and the y is mounted to the cross member arm at the same point that the motor and gear-reduction drop-shaft is mounted. The drop-shaft and wheel make one end of the Y, with another wheel with bearings at the other 2. Take a solid, hard-rubber type drive wheel, such as from a forklift, cut gear-teeth into that, with a ring track inside the paddlewheel to correspond with the contact area, then use the off-cuts and make more , as the teeth, for the inside of the ring. The drive gear/wheel and idler wheels don't need to exert any pressure on the ring, just hold the thing steady, so the teeth don't slip and everything stays aligned. That cog and ring-gear arrangement IS that 4.5:1 final reduction drive, that converts that lawnmower wheel to paddlewheel drive.

    Just like the boat hull, I can picture it, in my head, but I can't draw it. If I can describe it well enough to make sense to ONE person, it should work. How many people that couldn't draw, ever made something that worked? Millions, or Billions? How many thinking people, without a grasp on formal schooling ever made something that works?

    Hypothesizing and trivializing are different subjects, and not interchangeable. Dismissing ideas out-of-hand is trivializing, trying to find workable ideas is hypothesizing.

    I'm not a trained, certified anything. Formally, you could say I have a High School education and some college. That 'some college' includes aviation mechanics courses, studies toward a Physics degree, toward an engineering degree, toward an aircraft Pilot's degree, toward a Theatre degree, and more beside. As circumstances and life changes made it necessary, I tried, repeatedly, to go into fields that suited me. I can't hang some Masters Degree document on my wall, but I have more than enough credit hours for one. For one reason, or another, I have had to quit each program I entered. The last one was at East Texas State University/Texas A&M-Commerce, toward a theatre teaching degree, when I developed total foot drop. Corrective surgery gave me back my leg, but I couldn't afford to get back into school. Between the nerve damage and other back problems, my ability to work was ended. I've had at least 5 strokes since.

    Don't get me wrong, but I CAN form a complete thought, on my own--MOST of the time. SOMEtimes, I can't think past keeping up with my pill schedule. I recognize my fluctuating ability/inability, and that is why I get into discussions like this, especially on subjects of my ideas and projects. If I can find the problems, then solve them, I'm a step, or more, ahead. Brain-sweat vs brawn. I don't have much, if any 'brawn' left, but I can use brain-sweat to overcome that. Work smarter, not harder. I tell my kids, and anyone that will listen, I'm a professional lazy man. I will find the easiest way I can, to get almost anything done; so I don't have to go back and do it over, or fix it.
     
  3. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    Nice concept, but I have neither the money to buy a boat, nor anywhere to keep a catamaran/pontoon boat. The wheels and that lower-unit would be buried in the muck, here and that hull would have to be enormous. to keep to a ft, or less, with a cabin structure on it.

    The shrouded prop is a nice touch. Properly designed, a shroud can increase thrust by up to about 15%, or be used to reduce the size and power of the motor and prop, with the increased efficiency.

    via Google Translate:

    Bel concetto, ma non ho né i soldi per comprare una barca, non dovunque continuare una barca catamarano / pontone. Le ruote e che basso-unità sarebbero sepolti nel fango, qui e che lo scafo avrebbe dovuto essere enormi. per ridurre al ft, o meno, con una struttura di cabina su di esso.

    La prop avvolta è un bel tocco. Progettato correttamente, un velo può aumentare la spinta fino a circa il 15%, o può essere utilizzato per ridurre le dimensioni e la potenza del motore e puntello, con la maggiore efficienza.
     
  4. WindRaf
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    WindRaf Senior Member

     
  5. Rurudyne
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    Rurudyne Senior Member

    An older carburated scooter mower could be equipped with a marine-style carburetor I suppose. A nice, relatively simple solution.

    One thing about hub motors, mentioned earlier, is not the size of the wheel they are attached to but the forces they are designed to endure. That does't mean a hub motor wouldn't work but that it might need custom parts to replace the light weight for-bicycle transmission. I would investigate if any models are marketed for hill climbing or, um, really large persons.

    If you were going to do customized transmission you might as well investigate building a genuinely large diameter hub motor using several controllers for the numerable magnets which would run at a much lower base rpm (double the diameter, basically half the rpm for a given power) ... but it might be a crap shoot if your early efforts were actually efficient or durable and working your way through several prototypes could get pricy. Mind you, doing that might be fun in and of itself if that was already an interest of yours (this has been something that has temped me just for the doing, but only a little).
     
  6. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    The lawnmower already has 2 hubmotors and gear-boxes, to reduce speed and multiply torque. One for each side. I think my solution for more reduction is probably the simplest reasonable solution. It has all of the necessary gear reduction, should be fairly light, and is easy to hide.

    For the hull, I need to float as shallow as I can, plus to put most of the weight low, down in the hull, to keep it stable. A box scow would work, but the flat bottom will get stuck, in the mud we have, and the box front is difficult to move through the water, needing more power. The wide V-bottom of this hull design lets me work loose from the mud.

    A jon-boat is a simple work/utility design, made of mostly flat panels, with some curve at the front, to pass through the water easier. Very stable and supposed to be easy to build.

    From Google Translate:

    Il rasaerba ha già 2 hubmotors e ingranaggi-box, per ridurre la velocità e moltiplicare la coppia. Uno per ogni lato. Credo che la mia soluzione per ulteriori riduzione è probabilmente il più semplice soluzione ragionevole. Ha tutte necessarie riduttore, dovrebbe essere abbastanza leggero, ed è facile da nascondere.

    Per lo scafo, ho bisogno di stare a galla come superficiale che posso, oltre a mettere la maggior parte del peso ridotto, giù nello scafo, per mantenerlo stabile. Un barcone scatola avrebbe funzionato, ma il fondo piatto otterrà bloccato, nel fango che abbiamo, e la parte anteriore scatola è difficile muoversi attraverso l'acqua, che necessitano di maggiore potenza. L'ampia V-fondo a questa carena mi permette di allentarsi dal fango.

    Un jon-barca è un disegno semplice lavoro / utilità, in pannelli prevalentemente piane, con qualche curva nella parte anteriore, di passare attraverso l'acqua facile. Molto stabile e dovrebbe essere facile da costruire.
     
  7. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    Realistically, though I'm using the idea to drive a paddlewheel, it is more like using the lawnmower wheel into a bulldozer sprocket. Since I can am effectively reducing the sprocket to wheel diameter, plus the rubber teeth, then, driving the larger ring gear, inside of the wheel, then to the paddles attached to the outside of the wheel... The effective wheel and tire diameter may actually remain the same. Hamster inside of a hamster wheel... :p
     
  8. gonzo
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    gonzo Senior Member

    You accept some things as true because "otherwise they wouldn't have been suggested". However, suggestion that don't agree with your plan you disregard as useless.
     
  9. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    What's wrong with it? What am I overlooking? Show me where it doesn't work? What am I disregarding as a better, easier, cheaper option? Going strictly with outboards and a fake wheel?

    That's what this whole thread is about. Hammer-out the details and reduce the problems to a minimum. That's why I've asked for help. If at all possible, I want to be able to use straight electric power, for at least SOME of the time.

    Hammering out the details is how the hull got selected. The only adjustment to the jon-boat hull is a transition up to the transom, inside the sponsons/wheel-arms, so that nothing extends below the hull bottom and to gain clear access for the wheel to turn in the water. Easy way to do that is create a step and use a flat panel, angled up to the transom. Basically, create a semi-tunnel hull, probably from the frame, ~4' ahead of the transom, so it's not an abrupt angle. From there, back, the sides begin to act like pontoons. It means the ballast (batteries) will be a bit further forward, but they will be placed after the whole shebang is built, specifically to allow me to adjust the balance and level the deck.

    Rather than have one modest outboard, I should be using 2 even smaller ones, just to reduce the housing size, for better wheel clearance and easier concealment. That allows me a central sponson/wheel arm, or cantilevered boom, to mount the lawnmower drive, as well, but, since they are drop-axle drives, I could also mount to the transom, where a central outboard would be and eliminate that 3rd piece. It's restricted to a horizontal position, but there are several mounting options.

    The hard part, as I see it, is cutting and placing the cogs and ensuring that the inside wheel circumference, to the outside of the wheel/ring-gear are directly compatible, to maintain proper tooth spacing. I've supported both ends of each wheel with quality bearings, reduced friction and mechanical complexity, added light-weight/low-friction rollers to minimize lateral forces that would otherwise damage the entire mechanism. I've maintained the appearance and function of the sternwheel boat, by hiding the drive units between the wheels, rather than needing to drive both ends of each wheel. No chains to continually grease, no belts to stretch and slip, no building/jury-rigging of multiple complex gear-reduction systems, from inadequate parts that weren't designed for driving wheels.

    Since I'm planning to put the drop-axle drive inside the wheels, I could get away with just one idler wheel, on the axis as the drive-cog-wheel and central axle.

    I can put a 'trash-ring' (for lack of a better term) on both sides of the drive-cog to minimize fouling.

    The drop-axle gear reduction system has both a wheel brake, and it can freewheel, so less stress on the motor and gears, for slowing and reversing, something the original sternwheelers do not have, plus the 'emergency' brake, to lock the wheels, in any position, for any reason...

    I've found what appears to be a workable solution, that overcomes the various issues encountered, so far, including the necessary power requirements. 6 knots is a respectable speed, for the purpose, with backup power, for emergencies and extended range.

    By placing the drive inside the paddlewheels, on a central sponson, I can minimize the central sponson, and maximize the paddlewheel widths, more effectively camoflaging the drive. By using trash-rings and an idler wheel, rather than a pinch-wheel, I reduce the possibility of jamming the drive. I can add another idler wheel, perpendicular to the main one, of there's still any tendency to flex across the axle axis.

    I've tried to give a complete thought process and reason behind everything I think is in question. Each wheel is properly supported, mounted with automotive pillow-block bearings, driven with minimized side forces, by what should be an adequate system,... The drive system should work as described. I have tried, to think of all the reasonable scenarios, and then designed around the problems I can find, with as little added weight as possible. and as much reliability as possible.

    If it means anything, the gasoline version uses a hydrostatic drive transaxle, but also has power lost, to drive the mower-deck.

    With all sincerity, I am asking: What do you see wrong with this system? What other thing do you think I haven't accounted for? I freely admit, it's a complex project. By hashing out as many problems as possible, beforehand, it has much more going for it than if I start fabricating without forethought. I've asked for help, because I know there are things I DON'T know. We've hammered out a lot, so far.

    Next week I start building the shop space. Once I get that done, THEN I start buying and cutting materials. Even after I get the hull done, I will move on to the cabin. Still plenty of time to work on the drive-line, if it still seems to be an issue.
     
  10. gonzo
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    gonzo Senior Member

    The main thing wrong is buying and cutting materials before having a complete design.
     
  11. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    As far as I can see, the only thing left is the drive system for the wheels and that's even got the vast majority into a workable solution, and wiring for lights and horn. Hull, cabin and wheelhouse, drive-line, reserve drive-line, approximate location of the batteries, solar on the mollicroft and pilot house roofs. Storage will be under the foredeck and/or under the boxes along the sides, wherever there isn't flotation foam and batteries. Only thing left, that I can think of, is the side-decks, which will be either fold-up, or removable.

    I don't have any drawings, if that's what you mean... Haven't had any offers to do CAD, or any analysis, so I'll have to work with what I have found and stick with the decisions made. I'm no artist, but I can do the measurements on paper, then transfer them to wood and other materials, but even that is several weeks away.
     
  12. P Flados
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    P Flados Senior Member

    Those with the most experience tend to recommend against the "just build it" approach when there are key elements than can undermine the whole effort.

    The above is based mostly on the poor track record that they have seen when this approach is taken.

    Then again, I am certainly not going to throw any stones as this is pretty much the way I have gone about my: http://www.boatdesign.net/forums/multihulls/small-tri-test-platform-51551.html

    However, for this one I would strongly recommend holding off on buying / building anything more than you need to before you work out the details of the propulsion system. You do not want to put a lot of effort into the project only to get little or no use due to frustrations with the "least proven" aspect of the build.

    If you were working from proven plans, you could follow just about any sequence you wanted and eventually with enough effort you would have a boat that would work. Since you do not want to go this route, I would actually recommend a sequence more like:

    • Locate a cheap used drive train to cannibalize. I looked and have not seen anything electric that meets your stated cost considerations. You may find a beater golf cart or something electric, but don't ignore a cheap gasoline mower/lawn tractor if you find one. You can replace the gas engine with an electric motor at some later time (after you complete initial testing).
    • Either build the rear of the boat or a mock up.
    • Assemble your entire drive train. Get happy with it before you build anything else.
    • Build all / the rest of the hull as applicable. Do not bother to do any finishing at all, just get it structural and water tight.
    • Build your rudder or whatever you will use to steer.
    • Throw it in the water with a lots of random heavy items to get up to full loaded configuration.
    • Test drive it.
    • Fix all the stuff that does not work the way you need it to.
    • Until you get happy with the initial drive train performance, do not even think about the rest of the project.
    • Build the rest of the boat and do all of the finishing.
    • After you get a fully functional boat, you could then spend the cash needed to convert to electric (if you can justify the cost).
    The above gives you plenty of opportunity to either fix, adapt, abort or what ever as you progress.
     
  13. Rurudyne
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    Rurudyne Senior Member

    ^ this.

    It may even be worthwhile to build in scale first.

    Here's a web page for a guy who wanted to build an RC sidewheeler: http://www.ivorbittle.co.uk/Articles/Paddle wheel/The paddle wheel design study for the internet.htm which details some of his design work. His site has a number of other nice articles too, iirc.
     
  14. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    Sorry, in and amongst, I either said it wrong, or forgot to say...

    The dual small outboard, with freewheeling paddle-wheels setup IS the initial drive, until I can gather the parts for the electric, no matter how the electric drive goes together. I have been looking and think I mentioned the golf-cart transaxles, or possibly edited them out by accident, when trying to shorten posts (entirely possible). I've thought of, looked at, and discarded the idea of, trying to use the personal-scooter transaxles (Rascal and such). I even think I've managed to figure out how to mount them.

    I expect to avoid chain-drives and pulley-drives, for multiple reasons.

    Another thing that is for certain is I will NOT be building articulated bucket wheels. It's several levels beyond my tool collection, and multiple times the weight of a simple wooden paddle-wheel. The simple solutions are to either align the face of the bucket radially, or center the bucket radially. The offset difference is minimal.

    Once I get the electric drive in, the hidden outboards become the backup drive system, for any situation the electric can't handle.

    Structurally, she's a large jon-boat, with a steamboat style deck. The cabin and wheelhouse will sit on the deck, around combing, like an oversize cargo hatch, not down inside the hull. By extending the 'hatch-cover' up, I get my cabin walls, without having the water problems that building it up from inside the hull would give.
     

  15. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    thrust of electric vs hp

    Gonzo, and anyone else...

    Is there a rule-of-thumb, to compare outboards to trolling motors?

    All the ballpark figures I'm finding put it in the 20-35 lb thrust is approximately equivalent to the thrust of 1 hp, after drive-line losses. They also say the reason the watts to hp doesn't line up is that an electric trolling motor doesn't have those drive-line losses, so the trolling motor is twice as efficient (uses about 1/2 the wattage compared to the hp to watts conversion).

    Have to ask, since I'm not finding any reliable info on silent (or silencing) small outboards, just opinions, and that a 4-stroke is quieter than a 2-stroke.

    Ultimately, the goal is to maintain the sternwheel look, and silent operation. I still think the modified Cub Cadet drop-axle is the way to go, but, to simplify and use the boat, outboards are the current plan. Since it is not intended to move at some ridiculous planing speed, but move slow and silent, the options ought to be further explored.

    It also opens up the possibility of using a fixed-mount, under the transom-well, for some of the trolling motors that mount onto outboard motors. The hull is already going to transition to allow clear water to the wheel. That's a given. It's not any harder to make the last little bit square to the hull bottom.
     
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