Requesting Small Sternwheeler hull design and analysis help

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

  1. Rurudyne
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    Rurudyne Senior Member

    That would be a feature, to help keep the flat bottom from getting sucked into the mud, of one plan from 1913 that I recently linked to in another thread. One nice bit of advice that design included for simply driven radial wheels (non feathering or with independent gearing) is to stagger the floats so not as much paddle is leaving or hitting the water at a given time.
     
  2. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    These aren't available and, if they were, it would be a decent consideration. I can wish, though.

    I'm guessing at having 1 ft. of draft. With the transition to the transom, that's a foot of clear water for the drive, whether it's wheel(s) or props. Outboard, or trolling motors tend to extend below the hull and need that kind of clearance, so operating depth is really related to the bottom of the skeg, of the lower-unit, rather than hull depth. If both dimensions are the same, the only time the lower-unit can hit bottom is when the bow rises, the stern drops, or she's aground, anyway. Win-Win.

    Guess I need to keep working out the wheel drive. I have zero problem with that. Do like you said and have a small outboard on the transom, just in case, between the hull and wheel.
     
  3. P Flados
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    P Flados Senior Member

    I agree that electric is not practical for the power you would need.

    I am not sure about the implementation details, but a paddle wheeler with enough bite (plenty of blade in the water) geared only for slow speeds may actually be ok at dealing with windage and mucky situations. Think of a tugboat - they do not go fast but but they push a lot of water.

    The downside is that I do not think you are going to get the above without a big loss of anything approaching a "normal" cruising speed for the power you use.

    I am not sure how slow you are willing to go. If you want to stay at the low end of the power spectrum, you may want to considered looking around for a low dollar used riding mower to cannibalize. You can get most of your power train in a matched package: 10 hp or so electric start gas engine, clutch, transmission with forward and reverse, and two low speed output shafts to mount pulleys on for belt drives.

    If you want something closer to "normal" cruising speeds, it will be hard to get with a paddle wheel unless you throw some significant power at it. I just do not see this happening with your stated cost limitations.

    You mentioned regulatory hassles for a floating dock. What about a hybrid between the two concepts. Think small barge. It is legally a boat, but you could use it more like a floating dock with some minimal amount of mobility. The actual construction techniques could be more "dock" with the shape more "barge". I have seen this kind of stuff used locally as work platforms for dock maintenance and other such. You will still need some real power to achieve reasonable mobility. Again, I would be concerned that something like this does not seem to match up with your described budget limitations.
     
  4. gonzo
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    gonzo Senior Member

    If you have one foot of water in the stern, any outboard will do fine. A small tunnel will give it better performance.
     
  5. fredrosse
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    fredrosse USACE Steam

    Steam jet outboard...

    "Steam jet outboard..." These things are very simply "Snake Oil", one of the most inefficient propulsion schemes there ever was. People like to imagine that they are useful, they are not.
     
  6. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    2-Sternwheel Electric drive

    Fingered it out... :idea:

    I can modify the electric transaxles from 2 electric riding lawnmowers, hide them inside the Wheel Arms. Remove one side of each, make a couple of cover-plates, use the suspension mounts to help with mounting. Each wheel gets the other half of the transaxle to reach a middle arm, for a second bearing surface point, to keep the wheels aligned.

    Designed and geared for low-speed and durability. Intended, or not, that gearing multiplies the torque. 2-motors rated equivalent to between 10 and 20 HP each, depending on make and model.

    Boom! :D
     
  7. gonzo
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    gonzo Senior Member

    That's about 15KW. At 12V it will take about 1250A. The cables you need are about 1 inch in diameter. Also the batteries will be huge.
     
  8. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    Most EVs are wired at higher voltages. The Cub Cadet RZT-S Rider has a 48V-92 AH battery, for ~1hr runtime. I can bump that up, fairly easily. For one, I won't be using the motor(s?) to drive the cutting blades. Using higher capacity batteries won't hurt, either. Was figuring 6 heavy-duty AGM Marine/Automotive AGM bateries. For 48 VDC, I'll need 8, instead.

    Before ragging about the weight of the batteries, check the normal capacity if a pair of 16' jon-boats and start subtracting people, to replace with batteries. I don't intend this as some high-capacity party-barge. She's intended for a total of 3-4, minimal camping supplies, but with normal occupancy of 1-2 adults.

    Going downstream, it would give me a greatly extended time. If going farther, or upstream first, I would use the higher powered, hidden, inboard motor and save the battery. Win-Win!

    Tapped power (lights, outlets) can have its' own DC voltage regulator, without any need to tap a single battery, creating an imbalance.

    Can also get a small, portable 2kW genset, rewind and regulate for 48 VDC. No DC to AC inverter losses, unless I actually plug an inverter in, for some odd reason.

    3 solar panels in series would give ~51 VDC output, for solar trickle-charging.
     
  9. PAR
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    PAR Yacht Designer/Builder

    I recently rebuilt a 5 speed transaxle for a garden tractor. It was the MTD style Spicer, which along with the Peerless versions, are the most common. They used to build them to last a long time, but not any more. You might be better off with a Comer which are used on ATV's, though you'll have to work out some kind of clutch. You'll also need to work in some thrust bearing accommodation, as these puppies just don't put the load on them like a continuous duty paddle wheel will. I would think any reasonably sized wheel, will rip the 5/8" - 3/4" shaft of one of these in a heartbeat.

    A speed controller will handle everything, with a sprocket or V belt to axle arrangement. I also don't know what type of golf carts you're looking at, but a typical golf cart motor is 5 HP at 3,500 RPM and 48 VDC. I've seen some Franklin 36 VDC motors at 8 HP, but nothing near 15 or 20 HP. Have you seen the size of a 20 HP electric motor, not to mention the cost? The most common ones I've seen are 3.5 HP (2.6 KW) 48 VDC and these are about $500 each at retail. This requires over 5 KW of power, which isn't a small sum if running off of PV's (eighteen 300 watt panels) and a significant battery bank.
     
  10. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    I expect to use an electric direct-drive electric transaxle, though I don't know, with certainty, what it will come off of. I picked the Electric Cub Cadet as an example, but don't imagine it to have any shift mechanism.

    I was ball-parking the power, based off something I skimmed over and didn't bother to save. 5-10 shp should suffice for piddling and a 15 hp small outboard, hidden between the wheel and hull should cover everything else.

    Suppose I use the Cub Cadet specs. That gives me an actual travel of well over an hour, since I can travel upstream, using down to about 50% of the charge, then basically float back. Once I've done that several times, I'll be able to guess at how long I can drift along downstream, with power to return, and a safety margin, just using the Cub Cadet specs and parts, not including the savings for not using a cutting-deck, or changes in battery capacity. I specifically chose an electric riding lawnmower for the lower speed and power requirements. Even an electric ATV tends to run faster than I would need.

    At the moment, I may have access that others don't since 2 of my kids work at a resort with a private, 18-hole course, and they use EVs for almost everything.

    Cross that bridge when I get there.

    As for the solar, as I said, trickle-charger. If I need more power, I'll have that 15 hp hidden outboard, and eventually one of those 2kW portable gensets, rewound and regulated for the battery voltage. Been over 30 years, but I've hand-rewound a generator, when I had my Powerplant Mechanics electrical systems courses in'81, or '82. Matter of fact, I can probably find one cheap, if they already over-amped it and burned the alternator windings... ;)
    (imagine a Craig's List ad: Portable Generator for sale-$30 obo. Runs good, needs electrical work...) :D

    Should start on the makeshift shop space next week. Have a couple of other projects, but they'll benefit from shop space, and tooling-up, too.
     
  11. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    Hubmotor and gear reduction drive

    Woot! JACKPOT! :D

    The Cub Cadet RZT-S Electric uses a hubmotor and gear reduction drive for each rear wheel, with a top speed of 6 mph! :D

    They call it a Dual, Infinite Speed Drop Axle... It has 3-Phase DC hubmotors with keyed shafts for the wheels and splined shafts for the deck motors. PWM controlled. Waiting for a reply from their service dept., for the motor specs, gear ratios, torque ratings, shp ratings, max rpm, etc.,... ;)
     
  12. gonzo
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    gonzo Senior Member

    Those are for 18" wheels. The sternwheel will be at least five times larger diameter. That means that you need five times the torque and one fifth of the speed. In other words, the reduction ratio is wrong for the application. Your plan to "Cross that bridge when I get there" is a very expensive way of doing things.
     
  13. WindRaf
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    WindRaf Senior Member

  14. WindRaf
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    WindRaf Senior Member


  15. phrogjlf@yahoo
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    phrogjlf@yahoo JL Frusha

    I've found quite a few similar reduction drives, now that I have a better idea what I'm looking for. The ratio from motor to shaft, I don't have, but once I do, I can look for the right ratio. 4.5:1 reduction from what, is the question. May, or may not be more practical to get a single unit, rather than plug a reduction drive into another reduction drive. Depends on the weight and method of reduction, doesn't it?

    I could always use a friction drive, of wheel-to-wheel, or replace the wheel with a sprocket, or pulley, any number of options, but it CAN wait. I still have to make the temporary shop, much less the hull and cabin, then collect all the parts for the drive, including batteries, motor-controllers, a set of compatible controls, etc. Who knows, within the time it takes to get that done, the prices may come down and make the electric outboards from Germany a viable option. There are other options, even beyond these. Just a matter of sorting, counting the costs, checking the weights, and so on. I'll put in the drive, when I have it. Heck, with the already planned outboard, I could wait even longer, with just a free-turning wheel for looks, as previously suggested. It's a great idea. I like it,... but I STILL want to eventually have that electric wheel, or wheels. Nice thing is, the added rpm reduction increases the torque, with only friction and added weight losses.

    How might I use the wheel against wheel concept? a toothed track inside the paddlewheel, with a toothed rubber wheel could get it out of sight and do the reduction, at the same time... Put in a pair of idler wheels and I don't need pressure to maintain contact. use some fairly simple 'Y' brackets, like on the wheels of the thing from Damnation Alley... Home made planetary reduction drive... WHAT those added wheels look like is irrelevant, as long as the have bearings to minimize friction, and maintain the paddlewheel/track alignment.


    In the meantime, I can get the more important stuff done, like the shop space, the hull and the cabin/wheelhouse. I haven't drawn the first cut-mark on the first board. There are more things in my head, than what I've put in these posts.
     
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