# Anyone have articulation paddle wheel info

Discussion in 'Boat Design' started by justinDesign, Sep 24, 2007.

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### justinDesignJunior Member

Would like some info, pictures, videos, or links on articulating paddle wheels.

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### RAY TOSTADOJunior Member

Patent office.

Find a mechnical engineer.

propulsion is a function of paddle surfce area and low rpms.

Torque, not HP is required.

Little efficiency at smal diameters.

Ray

3. ### Guest625101138Previous Member

A picture:
http://www.ilsb.tuwien.ac.at/teach/PIX/hydro11.jpg
You can see the articulation levers on the inside of the far wheel.

A model:
ttp://kmoddl.library.cornell.edu/model.php?m=173

These ideas have not been highly developed as far as I know although I have read they are in use on full size vessels.

You should aim to operate the wheel at 10% slip to get high efficiency if this is important. This means the blade speed will be 10% faster than the design boat speed. This will need large blades if the boat drag is significant. If the boat design speed is 10fps then the blades will be doing 1fps backwards through the water. The Cd of a flat plate is around 1.1 so you can calculate the required blade area using your numbers.

If you use a large diameter wheel and shallow blades then the articulation is less important.

With deep blades the blade trajectory is important and it is not quite vertical all the way through its arc. Think of what a kayak paddle does when it enters and leaves the water. It needs to avoid scooping water up or forcing water down.

Like I stated in an earlier post you need to determine the hull drag so you can start the design process.

Rick W.

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### RAY TOSTADOJunior Member

I used an 8 blade 20" diameter. Not worth the time. Blades were 6"X 20" with only .6 square foot of surface. Barely a walking pace. Adding rpms was only slower. I was not lacking in torque.

I used a LIDO 14 hull.

Any thoughts on the linear paddle dives?

This is when a flat track is exposed for some run and has malltiple paddles submersed for this distance. Sort of like a tank track.

Ray

5. ### Guest625101138Previous Member

The standard paddle wheel is very simple but it needs to be designed.

I could do some numbers on the hull but it should move quite easily up to 3m/s (say 10fps).

To get an efficient wheel you need big paddles. I would be looking at something full hull width of 1.2m (4ft) and having blades 0.15m (6") deep. The numbers would be something like this (in metric):

Drag for 2.5m/s (say 5kts) (hull speed) is guessed at 30N. I would need to have hull lines to get this closer.

We assume there is one active blade in the water at any time so blade area is 0.18sq.m.

The thrust at speed difference of 0.3m/s is:

Force = 0.5 * 1000 * 1.1 * (0.3)^2 * 0.18 = 8.9N

This is not good enough so reduce efficiency by increasing speed difference to 0.6m/s:

Force = 0.5 * 1000 * 1.1 * (0.6)^2 * 0.18 = 35.6N

This is going to be close to doing the job but efficiency is down around 70%. This is as good as a typical outboard prop.

So blade speed needs to be 2.5 + 0.6 + 3.1m/s. Select diameter at 0.8m to give required rpm of 75.

The height of the wheel would be set so the blade is just fully immersed at the bottom of the wheel.

This is rough and would need hull data to get more accurate.

Rick W.

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### RamonaSenior Member

Rick,
I spent a week up the Murray at Renmark on a houseboat powered by a stern paddle wheel. The engine was a Holden red motor with an automatic gearbox, shaft drive to a tractor differential. The tractor rims were still in place and these had extensions welded on them probably 18 inches long. Can't remember how man blades but I',m guessing about 8. The blades were about 10 inches deep and just got fully immersed.
Very impressive and economic. Far cheaper to run than the other companies using pairs of outboards. This was a 4 bedroom boat.about 20 feet wide.

7. ### Guest625101138Previous Member

Ramona
Do you have a photo?

I picture two paddle wheels on either side of the axle. From your description I am guessing overall diameter from blade tip to tip is about 2m. The paddles operate with 10" of immersion. How wide are the paddles?

Rick W.

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### RamonaSenior Member

Sorry Rick no photo. The diff was locked and the blades were about 2 foot 6 inches wide. The four shallow rudder blades were directly behind the paddle wheels.I was particularly impressed by how effective they were as well. The use of the auto gearbox was clever, making gear changes with a cable over a fairly long run easy. Presumably it only had one forward gear. We travelled each day on a seven day holiday and used \$180 of petrol. As a professional fisherman I really needed a boating holiday but it was a family thing and I had to go. The company we used had all its vessels powered this way.

9. ### Guest625101138Previous Member

By my calculations there would be a good degree of slip on these blades. Meaning the blades would be moving backwards through the water quite fast.

I suspect the efficiency would be under 50% but likely to be more efficient than little outboard props pushing the big boat at slow speed.

Despite the poor efficiency the car motor should not be working very hard. Realistically it would only be delivering a few kilowatts to keep the boat moving at 5 to 60 knots.

I will have to try to find a photo. What part of the Murray and who was the operator.

Rick W.

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### RamonaSenior Member

The company was Libra Libra at Renmark. I'm sure they have a web page. The motor was probably operating at about 1500 rpm. I could not guess at the paddle wheel rpm but it was not much. We travelled at about 4 knots most of the time.

11. ### Guest625101138Previous Member

I found the site. It is Liba Liba. There is a couple of small images showing the boat under way. I can understand why you could not get a picture of the wheel. It is guarded effectively from the front and sides.

The water lift from the wheel is significant indicating reasonably high rpm. So I am estimating a lot of slip. I expect it would take less than 10kW to push the boat at 4kts so if the motor was working at 20 or 30kW it still would not be much over an idle for a holden car engine.

The whole thing would work so far within its capacity that a wheel efficiency less than 50% would still be better than a couple 2-stroke outboards churning away.

Paddlewheels also give high thrust when stalled out. Estimating periferal speed of 5m/s these paddles could generate about 1/2 ton of thrust so there would not be much that could stop them.

Rick W.

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### SamSamSenior Member

Here's a simple way. I don't know if it was ever tried or whether it works or not.

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13. Joined: Feb 2005
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### SamSamSenior Member

This one here I think was originally powered by a farm tractor with paddles on each rear wheel, but it seems they have re-done the system. There is a full description on the website. It's the boat "Roy C" pictured under "Boats of the ASA".
http://www.americansternwheel.org/main.htm

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### RAY TOSTADOJunior Member

My predictament was promoted by the fact that I already had a 14' hull with an existing engine well. I simply designed and built the paddle wheel to fit that well.

Had I been willing to make an entire proper well for a larger wheel I likely would have found some success. My current appraisal is that paddles are fine in massive applications, and in smaller foot pedel recreation models. It seems that the in between sizes suffer from an unappealing aesthic consideration. That is, a 16' hull would need a 5' tp 6' diameter, by 3' to 4' width. About 4' of which would stand up, caged, above the deck level.

My 14"X6" paddles, (8) by 20" diameter was totally insufficient to push a 600# hull and crew. I had just over .6 of a square foot to propel with at 100% force, and another 1 square foot at about 40% angle of attack the rest of the time. Not enough.

I do agree that the minimum emmersion is best. We got the performance peaked by having only 6" immersion and rpms down to where no water was being scooped by the upswing of the blades.

Sort of like running on ice. You can do it, but you have to control the torque your legs apply to reduce the slippage of your shoes.

Ray

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### RamonaSenior Member

Rick,
There is a platform either side of the paddlewheel, one side had a rowboat and the other a walkway about 5 foot wide. It was easy to walk back and view the whole works. You could walk on a small platform over the rudders too but that was supposedly banned while moving. The propulsion unit took up a lot of space but in this case it is cheap space.
In Ray's case with only a small vessel I think it could be done with a catamaran hull, something like a Honda or Briggs and Straiten belt drive reduction to a single paddle wheel centrally mounted.

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