Split Paddle Wheel propulsion design

I didn't say primitive technology is always inferior. My comment was directed only to paddlewheels, which is the focus of this thread.

 

For me propeller and paddle wheel are the same. Both of them are paddles. Like centrifugal and axial fan . Even more similarities between some kind of propellers and paddle wheels .
If somebody make real world experience , static bollard pull result prop v.s. paddle wheel will be surprizing.

 

Not quite, a prop has an airfoil shape, it produces a lift component, and the "warp" or twist in the blades can be tailored to the projected speed/rpm range.
But similar to a human paddling a canoe, the effective thrust component of a paddle wheel is in a fairly small section of its arc thru the water.
End plates and/or articulating buckets can increase thrust, but articulating buckets add a lot of complexity, (what they add in forward thrust they more than lose in reverse, no free lunch,) and end plates reduce the ease at which the paddle wheel can "slide" sidewise thru the water in turns, (reduced maneuverability).
However, both share an attribute, an increase in diameter always gains thrust effectiveness.
Obviously, we're talking about displacement speeds.

 

Not quite . You're right .
What if we create oblique split paddles with some airfoil crosscut ? No easy answers and lot of testing .
I remember somebody virtual design , double turbine like blades extend from the botttom of the boat.

 

Been used for many years, it's called a "Voith Schneider" system.
Provides thrust in any selected direction.

 

No I know Voith Shneider . Axis was logitudinal , only tip of the blade stuck out from the bottom of the hull.

 

We have done it. We call them propellers and are more efficient than the flat blades perpedicular to the boat.

 

That's different case , axis is similar to paddlewheel axis .

 

In that case it would be a thruster and move the boat sideways.

 

H.M. Screw Steamer Niger Towing the Paddle Steamer Basilisk, 1849
As much as I like a sternwheel, I'm certainly under no illusion that it in any way is superior to a propellor as a means of converting BTUs of thermal energy into usable thrust.
Any advantage they might have over a prop, (besides a fun/nostalgic/romantic experience,) is the ability to operate in stretches of shallow water that in the old days was usually filled with snags, and the ability to nose right into the banks to load/unload people and cargo.
They were also more maneuverable in tight channels than the early single-screw prop boats.
Here in the NW, small paddle steamers would work their way up small tributaries in reverse where there wasn't enough width to turn the boat around.
A pic in a book I've got shows a small steamer with a horse drawn wagon next to the boat.
Without any roads, (that didn't turn into mud pits at the first rain,) this method of getting product to market was common.
We think of those big Mississippi river boats, but there were hundreds of little 40>60' steamboats carrying goods/people all up-and-down the small rivers.
On the Columbia River the steamboats "last fling", so to speak, was hauling the materials up-stream to build the railroads on each side of the river that would put the boats out of business.
With dredging, sea walls, no snags, and developed facilities, the propellor boats could take over for barge traffic.

 

Nothing is simple here. Efficiency isn't simple . Propeller isn't simple device . I can probably beat 300hp rxp by 50-70hp outboard .
Paddlewheels aren't most efficient propulsion , jets also . But jets are very popular of different reasons , so maybe we should not cross out paddlewheels as possible propulsion system , maybe for fast water hiacynt cleaning.

 

From the Merriam-Webster Dictionary
efficient adjective

1. productive of desired effects especially : capable of producing desired results with little or no waste (as of time or materials) an efficient worker, efficient machinery
2. being or involving the immediate agent in producing an effect, the efficient action of heat in changing water to steam

The stated SOR from the OP:

It seems to me, you guys are arguing the wrong parameters for efficient.

-Will

 

Sadly Will, it's not about the OP, it's about the arguing.

Looks like the OP's had enough anyway, last seen Monday...

Happy New Year to you and yours.

BB

 

Unless it is a competition of who is heavier, I challenge you to show some setup where 50HP beats 300HP.

 

It's nothing unusual . Jetski hulls are not very effective and they are quite heavy beast . Jet propulsion is not on efficient side . So huge amount of power is applied sometines to achieve performance . If you compare this to relatively weak power source of tunnel boats : e.g 60 APX | Competition Outboards | Mercury Racing https://www.mercuryracing.com/engines/competition/60apx.html
I remember stock 40hp two strokes making 68 mph . It's huge power difference , and as I remember 200hp outboard can reach 124mph .

What about paddlewheel eficiency ? I'm cautious with obvious claims . Too many factors . And is much more to research .