paddlewheeler recuction drive

Discussion in 'Propulsion' started by xxdroom, Oct 30, 2014.

  1. parkland
    Joined: Jul 2012
    Posts: 700
    Likes: 6, Points: 18, Legacy Rep: 40
    Location: canada

    parkland Senior Member

    I thought the tire drive was good, and don't get me wrong, I think it might prove to be a good idea, but I don't think it is a good idea for what you are doing.

    The key for what you are doing, is a tractor drivetrain. A lot of them are at full speed in high gear under 50 km/h with giant wheels on them, so the bottom gear or 2 will be perfect for driving the paddle wheels, and the gears in them are made to pull and push constantly, under lots of throttle. This is ideal for a boat.
    The tractor will also have hydraulics, which you could use to run your rudder.

    As far as a jimmy rigged boat goes, this setup is ideal; the only parts not tractor parts are your paddle wheels with shafts, and pillow blocks. This means that if something breaks on the tractors engine or transmission, you can just head to a supply place and order it.
    As I said earlier too, get a manual air lockup diff, then you can unlock it, brake one wheel, and turn the boat around on a dime.

    What kind of v6 gas engine were you planning on using originally? a tractor engine will be designed to work, be it gas or diesel, it will be built to work a high duty cycle, like you need for a boat. Look around you can find tractors for a reasonable price, and this would be way better than a tire drive, especially for dual wheels (one on each side).
     
  2. parkland
    Joined: Jul 2012
    Posts: 700
    Likes: 6, Points: 18, Legacy Rep: 40
    Location: canada

    parkland Senior Member

    The ratio of transmissions really depends.
    Automatic transmissions have the torque converter, and the reason its a converter, is because it converts speed to torque.
    Some of them might be 1.5x, 1.8x, 2.2x, or 2.8x it all depends. There are tons of different ratings, effeciencies, etc.

    Just for an example, I have a ford 2008 6.4 diesel. The engine puts out approx 660 ft/lbs of TQ, and the transmission is rated at 1100 ft/lbs of TQ, after the TQ converter.
    Multiply the TQ (660) * the TQ converter ability (1.8) and theres 1188 ft/lbs of TQ.
    Some bigger transmissions I noticed are rated including the tq converter, others after it, it really depends.

    But, the moral of the story, an automatic transmission is not such an easy thing to calculate because there is so much RPM band that because of the TQ converter, changes depending on engine load.

    If you compare a manual to an automatic, the manual has a much deeper starting gear, because it does not have the advantage of a TQ converter like the automatic.

    The AOD ford trans overdrive is .67. Almost any overdrive transmission will be right around .7 over.
    Ideally, you don't want an overdrive transmission. Overdrive usually employs a planetary gearset that actually wastes energy. On a car it might save fuel from dropping the RPM's so much, but the ideal setup is always a direct drive, with the lower ratio on the rear end, or paddles in your case.

    There is no point in trying to use an overdrive transmission for driving paddle wheels, if you gear it that deep, your reverse will barely work.

    The allison 545 transmission used in the paddle wheel video, I have one in a bus I bought, and it is a very loose TQ converter. I can pin the throttle, and it hits 2000 RPM before it even starts moving. I assume it must also have a high TQ multiplication, maybe close to 3 or so.

    I hope you go the tractor drivetrain route, but if you don't, just rough it.

    Most medium duty trucks like buses and 5 tons will be over 2000 RPM at 100 km/h in direct drive gear.
    You don't want to be in direct drive, or the ratio will be so bad that reverse will barely move the wheel.

    I can tell you that my bus shifts into 2nd gear right around 20 km/h, so I actually think a direct drive would be fine, if you are going the "tire on paddle wheel" route.
    Remember that if the tire is driving the wheel, the size of the wheel does not matter, only the size of the tire, and the powertrain.

    I really don't think you want to "tire drive" 2 paddle wheels though, it seems like an engineering blunder. The tractor route is far more elegant.
     
  3. parkland
    Joined: Jul 2012
    Posts: 700
    Likes: 6, Points: 18, Legacy Rep: 40
    Location: canada

    parkland Senior Member

    OK here,
    just for example,
    If you used a dt360 with an allison 545 transmission from a bus,

    TQ converter is 1.96 ratio,
    1st gear is 3.45 ratio
    dt360 TQ is 475 @ 1800 RPM

    So if you're sitting still, and paddle wheels are stopped, and tires are against them, with 0% slip.....

    475 ft lbs TQ turns into 931 ft/lbs of TQ with the TQ converter. (*1.96)
    Transmission turns that into 3211 ft lbs of TQ. (*3.45)
    Rear end turns that into about 19266 ft lbs of TQ. (*6, about what rear end ratios are.)

    The tires on most buses or 5 tons are 40 inches. /2=20 inches.
    So 19266 ft lbs / (20/12 inches) 1.7 = 11332 pounds of tractive force.
    That is assuming 100% effeciency, so real world will be less.
    But that is showing how much force can be developed without further reduction.

    I would honestly just leave it direct like that, engine, auto trans, axle, tires, paddle wheel. I really don't like the setup, I still say tractor is better, but it should work, provided you have a method to apply pressure from tires to paddle wheels, and enough grip.
     
  4. xxdroom
    Joined: Oct 2014
    Posts: 41
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: lemitar, nm

    xxdroom Junior Member

    the problem with the tractor transmission is that most v-8 engines run at a far higher rpm.......... so to use a automotive engine like a 455 Pontiac may not work..........seems like I read that tractor engines have a built in low rpm .
     
  5. xxdroom
    Joined: Oct 2014
    Posts: 41
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: lemitar, nm

    xxdroom Junior Member

    augzillery .

    augzillery prop ?
     
  6. parkland
    Joined: Jul 2012
    Posts: 700
    Likes: 6, Points: 18, Legacy Rep: 40
    Location: canada

    parkland Senior Member

    Just use the tractor engine!
    Why would you want a v8 gas engine?
    A v8 like a 455 pontiac is going to be really good at burning a lot of gas for you.
    Just get a tractor, with the motor and transmission, remove the fenders, front wheels, seat etc, so all thats left is the engine bolted to the transmission and rear axles.
    Extend the shafts from the rear rubs outward, to the edge of your boat.
    Then bolt the paddles on that.
     
  7. parkland
    Joined: Jul 2012
    Posts: 700
    Likes: 6, Points: 18, Legacy Rep: 40
    Location: canada

    parkland Senior Member

    Just buy something like this, remove all the parts you don't need, and your left with a low RPM industrial drivetrain.

    All you need to do is build your side paddles with long enough tubes to bolt onto the rear axle, and weld the diff in the axle, or put a locker.
     

    Attached Files:

  8. slow fred
    Joined: Feb 2011
    Posts: 88
    Likes: 6, Points: 8, Legacy Rep: 61
    Location: florida

    slow fred Junior Member

    Just take the tire off and weld 2' spokes on the rim and weld the paddle wheel on to the spokes. Put one rig like this on each side to balance and to steer the boat. One in forward and one in reverse and you could spin it on a dime.
     
  9. xxdroom
    Joined: Oct 2014
    Posts: 41
    Likes: 0, Points: 0, Legacy Rep: 10
    Location: lemitar, nm

    xxdroom Junior Member

    I think you are right about this drive aperatis !

    & for one thing it don`t take high hp to turn thos paddles..... 50 hp would do it .
     
  10. parkland
    Joined: Jul 2012
    Posts: 700
    Likes: 6, Points: 18, Legacy Rep: 40
    Location: canada

    parkland Senior Member

    2 engines? We're having enough trouble figuring out 1 engine lol.

    I wouldn't bother with 2 engines on a side wheeler.
    On a prop driven boat, 2 engines adds redundancy and safety.

    If either engine fails on a side wheeler, I doubt you'd be able to do anything but go in circles. Not gonna get you home.
     
  11. parkland
    Joined: Jul 2012
    Posts: 700
    Likes: 6, Points: 18, Legacy Rep: 40
    Location: canada

    parkland Senior Member

    And there are lots of 40 - 60 hp diesel tractors. Easy to work on, and built to be worked hard, unlike car engine or transmissions.

    How wide is the boat going to be?
    Like 30 ft?

    The tractor axle width is probably 5 ft hub to hub, so that would leave about 12.5 ft from the hub on each side to the edge of the boat.

    Take the wheels off, get a welder or someone to cut off the wheel keeping just the middle part with the bolt holes, and enough to weld to the drive tube.

    The drive tube could extend right from that welded on hub, to the end of the paddle wheel assembly. Just attach it at the edge of the boat, with 1 or 2 pillow block bearings.
    The drive tube will need to be pretty stout.

    If the paddles were 4 ft wide, the drive tubes could be 16.5 ft long, and extend right from the tractor axle drive hub, to the edge of the paddle wheel on each side.

    If the tractor has a top speed under 50 km/h, I can almost garauntee one of the low gears will be perfect for driving paddles.

    And now you won't have any funny equipment to take care of or fix, just change engine oil and transmission fluid as per tractor owners manual, and grease the pillow block bearings.
    Should be a very reliable system I think.

    No chains, no belts, no custom equipment, other than the drive tubes, which should never really need any attention unless you hit something with them and bend the tube.

    Just a wild guess, but you would probably want something like 6 inch tube, 1/4 wall steel.
     
  12. AndySGray
    Joined: Jun 2014
    Posts: 296
    Likes: 13, Points: 18, Legacy Rep: 91
    Location: Cayman

    AndySGray Senior Member

    For Ocean, hell yes! :!:
    For docking with paying pax also pretty much mandatory.
    :confused:

    Think about the turning forces and where they act...

    Its about leverage and also flow.

    When steering, the boat will pivot around a point or vertical axis often refered to as the center of YAW. Depending on the shape of the hull, weight distribution and even wind on the superstructure among other things this will not be the middle of the boat, but anything in front of it will move one direction (port or starboard) and behind it they will move in the opposite direction.

    If your paddles are independant
    their thrust is like a lever, turning the boat BUT it is a short lever - basically half the width of the boat. For a prop, the lever is much longer - it could be half the length of the boat. Now while the paddle is providing most of its thrust in the correct direction, a prop is normally providing its thrust in the direction of the CoY so there is no turning force - hence a rudder is needed to direct that force sideways - this will never be 100% efficient but the massive extra leverage will still give a much greater turning force.

    e.g. for a 100 x 25 foot boat the paddle will give its thrust on a 12'6" lever and the prop on a 50' lever (4x greater turning power).

    Now you would still have a rudder on a paddle boat but it would be passive, like a sailboat, relying only on forward motion to generate sideways thrust - if the boat was at rest the rudder has no effect whatsoever.

    A propeller can create a flow of water even when the boat is stationary, and generate turning moments (forces) not related to the speed of the boat - this is very usefull in docking when the boat is at slow speed or stationary.

    And that is why the Waverley paddlesteamer has such a poor maneuverability - there is no rudder action at low speed and the paddles are not able to operate independantly!

    In heavier seas a prop will allow you to quickly correct if the vessel is turned by a gust or a heavy wave hitting the side of the bow, without losing the forward momentum.


    It was Brunel's SS Great Britain which sounded the death knell of the ocean going paddle steamers back in 1843, being the first propeller only vessel.

    There was a famous test on the river thames - they took 2 identical hulls and 2 identical engines and boilers, one was fitted with a single propeller, the other with twin sidewheels. They tied the sterns together and had the boats compete in a 'Tug of War', the result was very dramatic (in favor of the prop).

    :cool:
     
  13. slow fred
    Joined: Feb 2011
    Posts: 88
    Likes: 6, Points: 8, Legacy Rep: 61
    Location: florida

    slow fred Junior Member

    Maybe a couple of sails when everything quits
     
  14. parkland
    Joined: Jul 2012
    Posts: 700
    Likes: 6, Points: 18, Legacy Rep: 40
    Location: canada

    parkland Senior Member

    I agree propellers are more efficient, but there are some things about paddles that make them more favorable.

    Ease of engineering is certainly one plus.

    With the paddles and an engine with a radiator instead of water cooling, theres no chance for a shaft to leak below the waterline, paddles can be repaired without pulling the boat out of the water.

    Plus paddles can run safely in shallow water.

    Paddles are not the "best" solution, but they do work, and have worked for what, centuries before propellers?
     

  15. parkland
    Joined: Jul 2012
    Posts: 700
    Likes: 6, Points: 18, Legacy Rep: 40
    Location: canada

    parkland Senior Member


    lol why would anything quit :p
     
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.