paddlewheel

[rasorinc]

Is there such a thing as a more efficient paddlewheel? How about shape--rather than a flat wood board? spoon shape?? cupped shape?? thanks much.
Forgot, this will be a small application about 22".

[Rick Willoughby]

Is there such a thing as a more efficient paddlewheel? How about shape--rather than a flat wood board? spoon shape?? cupped shape?? thanks much.
Forgot, this will be a small application about 22".

Think BIG. You need large diameter and wide wheel/s. THe objective is to have very low slip and this requires large blade area. However shallow immersion is more efficient than deep immersion.

Think small with the arc of immersion. Less than 60 degrees is what I recommend for efficient operation.

If you get the basics right then blade shape or blade articulation does not matter much. I would recommend a slight lead with the blades so they produce a net uplift rather than down force. The blades should exit the water cleanly without lifting any noticeable volume.

The best size wheels will have some windage issues that you can be reduced by fairing around the wheel/s.

I have posted performance predictor elsewhere but it needs to be adjusted to suit the boat. You can play with the size of the wheels to determine the power required for various combination of diameter and width.

Rick W.

[rasorinc]

Rick, thank you for your reply. I drew out a 20" circle and divided it into 60 degree radiuse's and came out with 6 paddles. Reducing to 52 degrees + or -
I could get 7 paddles. Question-- if the paddles were, say, 18" x 6" out of steel and mounted on a steel ring all very strong could they turn at 3,500 RPM? And if so, could power and speed be an expected outcome?
Thanks very much, and I know I'm over my head on this. Stan

[messabout]

I'm over my head on this subject too. However I suspect that a paddle wheel turning at 3500 or anywhere near that speed, the result will be a lot of splashy foam and very little propulsion. Balance, too, will become problematic.

Examination of the geometry of the wheel and its interface with the water, easily leads us to the conclusion that bigger is better. Lay out a path tracing of a single blade as it moves through the water. You will see that there is much down force and subsequent up force generated. All that is useless expenditure of energy. The force that you want to generate is in the horizontal plane. A big wheel is far more efficient in that regard, and a giant sized wheel is even more efficient.

A wheel in the size that you are contemplating is better suited for mixing daquiris or margaritas for a large party.

[Rick Willoughby]

Rick, thank you for your reply. I drew out a 20" circle and divided it into 60 degree radiuse's and came out with 6 paddles. Reducing to 52 degrees + or -
I could get 7 paddles. Question-- if the paddles were, say, 18" x 6" out of steel and mounted on a steel ring all very strong could they turn at 3,500 RPM? And if so, could power and speed be an expected outcome?
Thanks very much, and I know I'm over my head on this. Stan

You need 12 paddles because you want to have at least ONE always in the water. With 6 combined with 60 degrees of immersion you will have a brief period with no paddle in the water.

The speed of the wheel will depend on the speed of the boat. My initial impression was that you were making a 20" scale model boat. I did not relate the 20" to the size of the wheel. For a full size boat 20" is hopelessly small if you seek efficiency.

The efficiency is primarily related to the slip of the paddles. The peripheral speed would ideally be 10% faster than the boat speed meaning the paddlewheel would be a bit less than 90% efficient. This usually results in a massive wheel relative to the boat. A wheel of practical proportions can usually give better than 75%.

If you were to spin a 20" wheel at 3500rpm it would be an excellent fountain but not much value in driving a boat.

If you provide some detail on the type of boat and target speed I will give you the wheel size required to get around 75% efficiency. I expect you will be surprised by how big it needs to be.

Rick W

[rasorinc]

Thanks very much for the input and your knowledge. I thought I might be chasing a wild hare and you just proved it. It might make a big blender.....
I'll drop my idea now. Thanks again, Stan

[tom28571]

Rick,

You seem to know a lot about paddlewheels. Have there been any successful articulated paddles that had only vertical paddles? How about tip fences on the edges of paddles? I've spent a number of hours watching paddlewheels thrash through the water on a riverboat and wondered about these things.

[Rick Willoughby]

Tom
I have not built a wheel but have looked at design information and validated it against various examples I have found and some basic test information from human powered wheels.

If the wheels are sized correctly and positioned properly then things like blade shape and articulation have less benefit.

There are certainly articulated paddles in operation and they are regarded as successful.

THere is an array of paddlewheels shown in this video clip:
http://www.youtube.com/watch?v=-QjRM-cQpHw
If you look carefully you will see many examples and get an idea of the different performance. Even the best of the paddlewheelers has under sized wheels in my view. However it still performs well against the competition but I doubt that many of the boats have well engineered props. A good canoe could do 7km in about 35 minutes so none of these boats are very impressive.

Look through the video a few times and pick out all the wheels. It is interesting to watch Hydrodynamosaurus at the start. You will see it kicks up a lot of water until it gathers speed and as the slip reduces there is less wasted power. A bigger wheel would cause even less spray. Also notice that the paddlewheel gives the best acceleration.

Rick W

[boat fan]

I really enjoyed watching that .

So Rick , in terms of total overall efficiency , how does a paddle wheeler compare with a conventional shaft / prop setup , in a power boat assuming both systems were configured optimal. Also assuming the same boat of course .By efficiency I primarily mean fuel consumption , power input , for a given arbitrary speed .

[Rick Willoughby]

So Rick , in terms of total overall efficiency , how does a paddle wheeler compare with a conventional shaft / prop setup , assuming both systems were configured optimal. Also assuming same boat of course .By efficiency I primarily mean fuel consumption , power input , for a given arbitrary speed .

Peak efficiency for either prop or paddlewheel is up around 90%. Realistically after allowing for windage of wheels or appendage drag on a prop they both end up more like 80%.

Problem with paddlewheels is that they do not suit rough water applications.

Problem with propeller is that it is not suited to shallow water or obstacle ridden water at least for efficient configuration.

So the selection is really application specific. With good design either system can achieve high efficiency.

Rick W

[boat fan]

Thank you Rick.

80 % .....Quite impressive :)

[tom28571]

Thanks Rick, a very interesting video.

I do know that the maintenance on the paddlewheels was way beyond any propeller boat I have ever experienced. Having driven both, I find it difficult to believe that a paddlewheel can be as efficient as a propeller. A propeller can operate at its max efficiency all 360 degrees of rotation while a paddle wheel blade only reaches max thrust at one point, dead bottom center. The rest of the time it is immersed, it is fighting gravity and using energy to do it. A simple view, I'm sure, but it seems reasonable.

[Rick Willoughby]

Thanks Rick, a very interesting video.

I do know that the maintenance on the paddlewheels was way beyond any propeller boat I have ever experienced. Having driven both, I find it difficult to believe that a paddlewheel can be as efficient as a propeller. A propeller can operate at its max efficiency all 360 degrees of rotation while a paddle wheel blade only reaches max thrust at one point, dead bottom center. The rest of the time it is immersed, it is fighting gravity and using energy to do it. A simple view, I'm sure, but it seems reasonable.

The main point of the video was to show that a well designed paddlewheel will be as efficient as a prop. Hydrodynamosaurus has bettered many propeller driven boats.

If the water is only 1ft deep you can get much more efficient operation with a large diameter, full width wheel on a moderate size river boat than having a small exposed prop or jet thruster working at very high velocity ratios. Also the first log that comes along will destroy the prop or decent chunck of weed will foul the jet inlet.

Most current paddlewheels are sized for times of abundant fossil fuel so efficiency has not been a design priority.

Rick W

[Ramius41]

I'm not sure if this video has been posted before. But it shows a rather fast paddlewheeler!

http://www.youtube.com/watch?v=02DKzQFsgJU

http://www.youtube.com/watch?v=meDcNK0-tio

[Stumble]

Just curious what if any andvantage a tread instead of a wheel might be? Think something like a tank tread... I can see it would allow a lot more horisontle force to be applied with relatively low vertical force.

[Rick Willoughby]

The fastest ones use treads so the efficiency is better than wheels. Here is a good comparison:
http://www.youtube.com/watch?v=tccrBWtSda4

The amount of spray is indicative of wasted power. You can draw your own conclusion.

Rick W

[FAST FRED]

Just curious what if any advantage a tread instead of a wheel might be? Think something like a tank tread.

Works in reverse even better.
I had a friend that took 100ft of fire hose and installed wood hinged flaps by sewing them on.

He took a front spindle from a car and mounted it with a wheel (no tire) on the stern of his anchored boat .

With the belt as an endless loop dropped into a 2K -3 K tidal flow he was able to power a small alt by having it run a rubber wheel ( solid from shopping cart.against the rim of the car wheel.

It worked like the old generators we had on bicycles as a kid , but it created enough energy to keep a small cooler cold.

Left unattended it still worked , except when a fish guy would chop it into his prop be passing too close astern.

This of course was to remove energy from the water , not put it into the water as a paddlewheel would ,

but it kept the BEER COLD!!

FF

[woodchuck]

The Oh! Susana, a 78 foot stern wheeler with a stainless steel hull used a gallon an hour of diesel at 8 knots. I didn't believe the gauge and stuck the tank everyday. The wheel has less slippage than a prop and has a lot more surface pushing the water.
There is a lot more maintanence as there is a lot of strain and hammering on the buckets. They slam the water hard ever cycle and then unload. Checking the bolts in the buckets was a daily job and we frequently found missing bolts even with self locking stainless bolts. I would use lock tite if it were mine.
The boat had no vibration, not even rings on the surface of my coffee on the dash. Pans on the stove or dishes on the table did not move. I haven't found that to be the case with displacement hulls with props.
The drive chain is a constant nightmare in salt water. We tried everything we could find and plain old grease liberally applied every evening was the best but had to be done everyday. STP, chain lube, lith were all tried but were poor.

[FAST FRED]

plain old grease liberally

Have you tried synthetic wheel bearing grease?
It sheds water , and is cheap to try.

FF

[woodchuck]

Sure did but wasn't any better. The constant spray was just too much for any thing to last at all. Motorcycle chain lube is very sticky but didn't work long either. Maintaining the chain was just a daily chore that had to be done like a lot of things on a large boat. It was worth it for the fuel savings and the looks it got. Not many real paddle wheel boats out there.

[tom28571]

Sure did but wasn't any better. The constant spray was just too much for any thing to last at all. Motorcycle chain lube is very sticky but didn't work long either. Maintaining the chain was just a daily chore that had to be done like a lot of things on a large boat. It was worth it for the fuel savings and the looks it got. Not many real paddle wheel boats out there.

Do you have trouble with broken link pins? That was the major issue and grease was smeared by the handfull on the chains. Having a chain break due to a broken pin slipping completely out was a constant fear. Inspection every 30 minutes was the order of the day. Replacing broken pins on those big chains is a dirty job.

[woodchuck]

No pin problems but we greased every day. We had problems with the bucket bolts coming out. Whe wheel was stainless so didn't corrode but it did get stress cracks which we welded since we had a welder in the engine room. The owner was a tool and die man so we had a mini machine shop on board.
He designed the power steering using the parts from a Ford F-450. It was great Very light and positive feel. Did find out it needed a huge resevoir because when the engine was off all of the fluid returnd and the stock can was't big enough. Nothing like a few quarts of power steering fluid on the deck to make things interesting.
I believe the wheel sprocket was from a cement mixer and had a huge chain. There was a marine transmission chained to a reduction box that was chained to the wheel. Only the outside chain was a problem.
On smaller chains there are several grades of chain. I have seen motorcycles destroyed because the owner bought ag chains for much less than ones designed for bikes. A ten horsepower chain on a 1000cc bike is going to break quickly and usually jam betewwn the sidecase and the sprocket, tearing a hole.
Buy the best chain you can that is rated for the job. Size alone is not the only important thing.
The chain had been from Ohio to south Texas and back to ohio with out replacement so I guess the grease problem wasn't as bad as I thought. It was just an aggravation to walk the chain around and brush on grease every day, particularly since I always seem to wear some when finished.

[Rick Willoughby]

The Oh! Susana, a 78 foot stern wheeler with a stainless steel hull used a gallon an hour of diesel at 8 knots. I didn't believe the gauge and stuck the tank everyday. The wheel has less slippage than a prop and has a lot more surface pushing the water.
........

Woodchuck
Thank you for the information.

I would like to see a photo of the Oh! Susana if you have one. Also more technical information on the engine and size of the wheel.

Rick W

[woodchuck]

Lost the first reply so will try again.
I am in Matagorda, Tx in an RV so have no pictures with me. Send me an address and I will get it to the former owner who will probably answer you. He was very proud of the boat.
Things I know about it.
3/8 stainless hull
10X10 Wheel
composite buckets (seem to cause problems
and were replaced with wood)
4-51 Detroit
5 waterproof bulkheads
Drew less than 18 inches of water
handled like a log at slow speed
House like interior which ws poor. The owner bought
it that way and just never changed it.
Layed out like an apartment not a boat or RV
Hard to dock in conventional way since wheelhouse
could not see rails.
White trimmed in red with red smoke stacks (fake)
attention getter
I understand it was insured for $500,000, sold for
less.
Joe is 86 but very active so I imagine he will answer you
Chuck
Greenwoodchuck2@aol.com

[Rick Willoughby]

Chuck
I have sent email that you or Joe can reply to.

Rick W

[woodchuck]

paddlewheels are more complicated than they first appear.
They are most efficient when the bucket is flat. A cupped bucket would carry water up and end any advantage they got on the way under. The buckets are most efficient when barely submerged. Water over the top puts drag on the way air in a vaccum behind a car does. The boats are difficult to balance since the bow climbs a noticeable amount. The old boats just loaded for it. Pleasure paddlewheelers today put weight in the bow hold and live with it. It isn't that important if not hauling freight for a profit.
The old steam boats had huge steam engines and used rather cheap fuel so they could overcome any flaws with brute force. Horsepower available from steam is awsome and the engines are mostly very low tech with little precision machine work. I wonder why no one is building any today. Scrap material to burn is very available. I guess it is just too much bother to wait to start and watch pressures.

[tinhorn]

You can download a free PDF of a bunch of ancient paddlewheel specs, data, and formulas here: http://www.lulu.com/content/1948578 .

[woodchuck]

Good stuff. The net actually contains a huge amount on paddlewheelers considering how few there actually are today. I wonder if it would be economical to build steam powered wheels today? I understand a prop is better above 300 horsepower but don't know why. It may have to do with size or tech available in the past.

[tinhorn]

Well, grasping new technologies is what we humans do. I was disappointed in the amount of readily available paddlewheel info I was able to find when I was searching. Fortunately, I had a lot of time on my hands when I assembled that collection.

Judging by feedback in another thread here (which I've lost track of since I've been absent for awhile) paddlewheels are excellent devices in certain applications.

[ancient kayaker]

I didn't realize chains had been used for driving paddles; sounds like a recipe for high maintenance.

I have memories as a child being in the engineroom of a sidewheeler watching the huge steam engines effortlessly pushing the massive cranks. .Much later on a sternwheeler I watched the pair of big pushrods drive the wheel.

More recently I was on another sternwheeler and went back to watch the action; nothing. The damn wheel was a fake, rotating courtesy of the wash from the diesel driven prop! And they call it progress!

Maybe I'll build a steam paddlewheel drive for my kayak.

[woodchuck]

Chains do require looking after as do pitman arms or anything else around water or salt water.
I was frequently asked what drove us. Most people thought the wheel was for decoration. A number of them are just fakes on tour boats.
Sure would load a kayak but I saw an ad a few years ago for a kit to put a wheel on a jon boat and use a B and S motor. In stumps or shallows it would work great.
There was also an article about a Yukon Delta house boat with a wheel added.

[drmiller100]

are there many planing paddlewheels?
I was thinking it would be fun to put a paddle wheel into a jon boat.

i did hunt down a guy who had this video.
http://www.youtube.com/watch?v=JGdkHIMbHYM

he claimed you could ride around the lake and steer by leaning.

[Rick Willoughby]

http://www.youtube.com/watch?v=meDcNK0-tio&feature=related
http://www.youtube.com/watch?v=tccrBWtSda4
http://www.youtube.com/watch?v=eaGLNcIkSm0
http://www.youtube.com/user/fasttrackdriver

[drmiller100]

I would think the paddle tire guy would be faster if he turned his tires around so they "lifted" rather then "dug".

The worst thing you can do is throw water straight up in the air, as that provides downward thrust and lost work.
Lifting at the front of the tire isn't all bad. The worst thing that will happen is you climb up on top of the water and lose "traction."

I've done a fair amount of work with deep powder snow and snowmobiles, and the whole goal is to get up on "plane". You do this with lift as much as "thrust."

:) :) :)

[volkswagen50]

I can answer the question about why there are no steam powered ones easy enough. In the US, coast guard regulations required the engineer of the steamer to have 4 years of full time apprenticeship to run a steam powered boat. The Ticonderoga of lake Champlain ran into this issue in 1953, when all the engineers were in their 80's and new guys just couldn't get the needed experience. This is how the Ti ended up at the Shelburne museum.

The Ti used 2 tons of coal per hour at max speed. To use wood you need almost twice the amount. The best wood has 17m BTU per ton, coal has 26m BTU for its best type. the worst coal has 16.2M btu. Plus coal requires less handling.

It was a sidewheeler, but I still feel it relavent info. The Ti had paddles that changed angle as the went into and exited the water. i can't remember the name of the system, but it was commn in the mid 1800's on up to the end of commercial wheelers.

Thanks for all the info guys! I've always liked paddle wheel boats, so this is a good thread to learn some practicle info with.