Paddlewheels versus Propellers

[[email protected]]

Ron Wanttaja > wrote:
> Years ago, when there was a controversy as to whether paddles or
> propellers were most efficient for ships, the British came up with a
> simple test: They built two identical ships, with identical engines,
> one with paddles and one with a prop. They tied a rope between the
> sterns, and had the captains go to full power to see which had more
> thrust.

>Wikipedia says that "In 1848 the British Admiralty held a tug of war
>contest between a propeller driven ship, Rattler, and a paddle wheel ship,
>Alecto. Rattler won, towing Alecto astern at 2.5 knots (4.6 km/h)...."

>http://en.wikipedia.org/wiki/Propeller

Jim Logajan wrote:

>However, it is probable that the paddle wheel ship simply didn't have the
>right size paddles. Paddle wheels should be capable of efficiencies similar
>to propellers - but it takes very large wheels.

I used to think so, too, but an article a couple of years ago in
Flying, by Peter Garrison, set me straight. It was about Lift to Drag
ratios and Coefficients of Lift, and laid out what those mean not
only in terms of wings, but any foil, including propellers. A
paddlewheel cannot generate any more thrust than the torque applied to
its shaft can produce at the arm-length of the paddle, while a
propeller can produce more thrust because its blades can cut through
the medium with a minimum of effort and produce considerably more lift
or thrust for a given torque than a paddle will.

So we don't see paddlewheels on boats anymore.

I wish I could find Garrison's article again.

Dan

[a[_3_]]

On Nov 9, 2:39*pm, wrote:
> Ron Wanttaja > wrote:
> > Years ago, when there was a controversy as to whether paddles or
> > propellers were most efficient for ships, the British came up with a
> > simple test: *They built two identical ships, with identical engines,
> > one with paddles and one with a prop. *They tied a rope between the
> > sterns, and had the captains go to full power to see which had more
> > thrust.
> >Wikipedia says that "In 1848 the British Admiralty held a tug of war
> >contest between a propeller driven ship, Rattler, and a paddle wheel ship,
> >Alecto. Rattler won, towing Alecto astern at 2.5 knots (4.6 km/h)...."
> >http://en.wikipedia.org/wiki/Propeller
> Jim Logajan wrote:
> >However, it is probable that the paddle wheel ship simply didn't have the
> >right size paddles. Paddle wheels should be capable of efficiencies similar
> >to propellers - but it takes very large wheels.
>
> I used to think so, too, but an article a couple of years ago in
> Flying, by Peter Garrison, set me straight. It was about Lift to Drag
> ratios and *Coefficients of Lift, and laid out what those mean not
> only in terms of wings, but any foil, including propellers. A
> paddlewheel cannot generate any more thrust than the torque applied to
> its shaft can produce at the arm-length of the paddle, while a
> propeller can produce more thrust because its blades can cut through
> the medium with a minimum of effort and produce considerably more lift
> or thrust for a given torque than a paddle will.
>
> So we don't see paddlewheels on boats anymore.
>
> I wish I could find Garrison's article again.
>
> Dan

That's a more insightful argument than the ones I'd have made, eg (1)
no matter how large the paddle wheel, at least some of the energy
would be spent pushing down, than up, on the water, rather than
throwing it aft, and (2) a screw can be placed deep in the water with
less rooster tail losses. You can't get more power out than you put
in, but any effort that makes the thrust more efficient pays off.

Thanks for the tip.

As an aside, someone pointed out that a windmilling prop is a lot like
a wing flying upside down -- not nearly as effective, camber is on the
wrong side. Once mentioned it was obvious.

[Stealth Pilot[_3_]]

On Mon, 9 Nov 2009 11:39:07 -0800 (PST),
wrote:

>Ron Wanttaja > wrote:
>> Years ago, when there was a controversy as to whether paddles or
>> propellers were most efficient for ships, the British came up with a
>> simple test: They built two identical ships, with identical engines,
>> one with paddles and one with a prop. They tied a rope between the
>> sterns, and had the captains go to full power to see which had more
>> thrust.
>
>>Wikipedia says that "In 1848 the British Admiralty held a tug of war
>>contest between a propeller driven ship, Rattler, and a paddle wheel ship,
>>Alecto. Rattler won, towing Alecto astern at 2.5 knots (4.6 km/h)...."
>
>>http://en.wikipedia.org/wiki/Propeller
>
>Jim Logajan wrote:
>
>>However, it is probable that the paddle wheel ship simply didn't have the
>>right size paddles. Paddle wheels should be capable of efficiencies similar
>>to propellers - but it takes very large wheels.
>
>I used to think so, too, but an article a couple of years ago in
>Flying, by Peter Garrison, set me straight. It was about Lift to Drag
>ratios and Coefficients of Lift, and laid out what those mean not
>only in terms of wings, but any foil, including propellers. A
>paddlewheel cannot generate any more thrust than the torque applied to
>its shaft can produce at the arm-length of the paddle, while a
>propeller can produce more thrust because its blades can cut through
>the medium with a minimum of effort and produce considerably more lift
>or thrust for a given torque than a paddle will.
>
>So we don't see paddlewheels on boats anymore.
>
>I wish I could find Garrison's article again.
>
>Dan

paddle wheels still exist in australia. the murray river runs through
the old paddle steamer inland port of echuca in victoria where there
are quite a few paddle steamers that still run for the tourist trade
these days.
worth a visit and a day spent on the boats if you are ever in the
area.
australia's paddlesteamers developed as a separate technology from the
american sternwheelers. ours are side wheelers due to the winding
nature of the murray.

a proper australian sidewheeler is based on the rule of thirds.
the paddles are a third of the diameter wide and the paddle boards are
a third of the width deep. that's what works best.

www.murrayriver.com.au/paddleboats
www.emmylou.com.au
www.echuca.ws/...Paddlesteamers/The-Beginning-of-Murray-River-Paddlesteamers.html
that'll get you started.

I find this particular vintage history fascinating.

connection with flying? none! I wasnt flying the time I spent my day
on the boats. one of the few days I havent wished I was flying.
Stealth Pilot

[a[_3_]]

On Nov 10, 6:36*am, Stealth Pilot > wrote:
> On Mon, 9 Nov 2009 11:39:07 -0800 (PST),
> wrote:
>
>
>
>
>
> >Ron Wanttaja > wrote:
> >> Years ago, when there was a controversy as to whether paddles or
> >> propellers were most efficient for ships, the British came up with a
> >> simple test: *They built two identical ships, with identical engines,
> >> one with paddles and one with a prop. *They tied a rope between the
> >> sterns, and had the captains go to full power to see which had more
> >> thrust.
>
> >>Wikipedia says that "In 1848 the British Admiralty held a tug of war
> >>contest between a propeller driven ship, Rattler, and a paddle wheel ship,
> >>Alecto. Rattler won, towing Alecto astern at 2.5 knots (4.6 km/h)...."
>
> >>http://en.wikipedia.org/wiki/Propeller
>
> >Jim Logajan wrote:
>
> >>However, it is probable that the paddle wheel ship simply didn't have the
> >>right size paddles. Paddle wheels should be capable of efficiencies similar
> >>to propellers - but it takes very large wheels.
>
> >I used to think so, too, but an article a couple of years ago in
> >Flying, by Peter Garrison, set me straight. It was about Lift to Drag
> >ratios and *Coefficients of Lift, and laid out what those mean not
> >only in terms of wings, but any foil, including propellers. A
> >paddlewheel cannot generate any more thrust than the torque applied to
> >its shaft can produce at the arm-length of the paddle, while a
> >propeller can produce more thrust because its blades can cut through
> >the medium with a minimum of effort and produce considerably more lift
> >or thrust for a given torque than a paddle will.
>
> >So we don't see paddlewheels on boats anymore.
>
> >I wish I could find Garrison's article again.
>
> >Dan
>
> paddle wheels still exist in australia. the murray river runs through
> the old paddle steamer inland port of echuca in victoria where there
> are quite a few paddle steamers that still run for the tourist trade
> these days.
> worth a visit and a day spent on the boats if you are ever in the
> area.
> australia's paddlesteamers developed as a separate technology from the
> american sternwheelers. ours are side wheelers due to the winding
> nature of the murray.
>
> a proper australian sidewheeler is based on the rule of thirds.
> the paddles are a third of the diameter wide and the paddle boards are
> a third of the width deep. that's what works best.
>
> *www.murrayriver.com.au/paddleboatswww.emmylou.com.auwww.echuca.ws/...Paddlesteamers/The-Beginning-of-Murray-River-Paddles...
> that'll get you started.
>
> I find this particular vintage history fascinating.
>
> connection with flying? none! I wasnt flying the time I spent my day
> on the boats. one of the few days I havent wished I was flying.
> Stealth Pilot

There were/are sidewheelers "Up Over" too. There are some special
purpose ones used on shallow and weedy ponds, the wheels are
independently driven so the thing can be made to turn with zero
radius. There's the aviation reference, multi engine issues! Now
here's an idea not worth patenting. If the paddles were individually
articulated so that they were always normal to the direction of
travel, there would be less wasted energy pushing down on the water at
entry and pushing up on it at exit. Winglets to prevent edge effects
would be an additional touch of elegance. With these innovations they
might have withstood the invasion of screw driven for at least an
additional week or two.

[Brian Whatcott]

a wrote:
> ...Now
> here's an idea not worth patenting. If the paddles were individually
> articulated so that they were always normal to the direction of
> travel, there would be less wasted energy pushing down on the water at
> entry and pushing up on it at exit.

I have seen examples of articulated paddles in illustrations...

Brian W

[Dudley Henriques[_2_]]

On Tue, 10 Nov 2009 11:55:25 -0600, brian whatcott wrote:

> a wrote:
>> ...Now
>> here's an idea not worth patenting. If the paddles were individually
>> articulated so that they were always normal to the direction of
>> travel, there would be less wasted energy pushing down on the water at
>> entry and pushing up on it at exit.
>
> I have seen examples of articulated paddles in illustrations...I wish
> they would spank my ass, spanjk my ass, oh so hard.

> Brian W

Troll.

[george]

We had one on the Waikato where the paddle wheels were unpowered
ornaments. :-)
Strictly for the tourists.

[Dylan Smith[_2_]]

On 2009-11-10, a > wrote:
> radius. There's the aviation reference, multi engine issues! Now

Indeed there is. My multiengine instructor also owned a boat, a 35 foot
planing hull type boat with two large V8 engines, and of course separate
propellors. We went out on the 4th July, into Galveston Bay, one year.

The boat would happily do 30 knots all day long at what passed for
"economy cruise", if I remember right, on both engines. It steered
beautifully on two engines. The props, like some multiengined aircraft,
were counterrotating too. But that night one of the starter motors failed
on the engine that turns the "non standard direction" (i.e. the one
with the really expensive starter motor!) letting out the magic smoke.

We had to come back in on one engine. On one engine, it steered like a
cow, and lost about 90% of its performance - it would not do more than
about 5 knots full bore. Very reminiscent of the problems with multi
engine flying. Except, of course, for the lack of the falling-out-the-sky
bit if you got too slow.

[Franklin[_18_]]

Jeffrey Bloss wrote:

> On Tue, 10 Nov 2009 13:17:14 -0500, Dudley Henriques wrote:
>
>> On Tue, 10 Nov 2009 11:55:25 -0600, brian whatcott wrote:
>>
>>> a wrote:
>>>> ...Now
>>>> here's an idea not worth patenting. If the paddles were
>>>> individually articulated so that they were always normal to the
>>>> direction of travel, there would be less wasted energy pushing down
>>>> on the water at entry and pushing up on it at exit.
>>>
>>> I have seen examples of articulated paddles in illustrations...I
>>> wish they would spank my ass, spanjk my ass, oh so hard.
>>
>>> Brian W
>>
>> Troll.
>
> Enter poor mentally deficient Dudley Henriques, boyz n grrrls,you have
> to understand that in the mind of the retarded, kicking, screaming
> incoherently, and leaking body fluids from every orifice with the
> ability to expel them are all suitable substitutes for a "defence".


YAWN. You're losing your skills at making people angry.

[a[_3_]]

On Nov 11, 12:15*pm, Dylan Smith > wrote:
> On 2009-11-10, a > wrote:
>
> > radius. *There's the aviation reference, multi engine issues! Now
>
> Indeed there is. My multiengine instructor also owned a boat, a 35 foot
> planing hull type boat with two large V8 engines, and of course separate
> propellors. We went out on the 4th July, into Galveston Bay, one year.
>
> The boat would happily do 30 knots all day long at what passed for
> "economy cruise", if I remember right, on both engines. It steered
> beautifully on two engines. The props, like some multiengined aircraft,
> were counterrotating too. But that night one of the starter motors failed
> on the engine that turns the "non standard direction" (i.e. the one
> with the really expensive starter motor!) letting out the magic smoke.
>
> We had to come back in on one engine. On one engine, it steered like a
> cow, and lost about 90% of its performance - it would not do more than
> about 5 knots full bore. Very reminiscent of the problems with multi
> engine flying. Except, of course, for the lack of the falling-out-the-sky
> bit if you got too slow.

Even more aviation: you could not maintain altitude: couldn't get up
on to planning speed.

But 5 knots? My 25 foot swing keel O'Day (think of the keel as a
vertical wing) could do that in a reasonable breeze and it
was NOT a fast boat.

It hurts my head to think about what parts of the two engines were
common, and which were different.

[Morgans[_2_]]

"a" > wrote

>Even more aviation: you could not maintain altitude: couldn't get up
>on to planning speed.

>But 5 knots? My 25 foot swing keel O'Day (think of the keel as a
>vertical wing) could do that in a reasonable breeze and it
>was NOT a fast boat.
s
Not surprising, to me.

Every boat has a "hull speed" than can be calculated, relating mainly to
length, that applies in a strictly displacement mode. The longer, the
faster, generally. The O'Day 25 (used to have one) had a hull speed of
about 6 1/4 knots. To go faster you would have to apply enough HP (LOTS
more HP) to get up on plane, and I suspect the one engine in the power boat
did not have enough power to get it over the hump. Also consider that a
considerable amount of one engine's HP would be consumed by rudder drag,
since the rudder would have to be nearly 45 degrees to keep the boat going
straight.. Also, the 5 knots mentioned is probably not terribly accurate,
since the accuracy of a power boat's "speedometer" is not very good at low
speeds.

>It hurts my head to think about what parts of the two engines were
>common, and which were different.

Not that bad, I think. Camshaft, crankshaft, oil pump, water pump, harmonic
ballancer, distributor, alternator.

_ Jim in NC

[a[_3_]]

On Nov 15, 2:59*pm, "Morgans" > wrote:
> "a" > wrote
>
> >Even more aviation: you could not maintain altitude: couldn't get up
> >on to planning speed.
> >But 5 knots? My 25 foot swing keel O'Day (think of the keel as a
> >vertical wing) could do that in a reasonable breeze and it
> >was NOT a fast boat.
>
> s
> Not surprising, to me.
>
> Every boat has a "hull speed" than can be calculated, relating mainly to
> length, that applies in a strictly displacement mode. * *The longer, the
> faster, generally. *The O'Day 25 (used to have one) had a hull speed of
> about 6 1/4 knots. *To go faster you would have to apply enough HP (LOTS
> more HP) to get up on plane, and I suspect the one engine in the power boat
> did not have enough power to get it over the hump. *Also consider that a
> considerable amount of one engine's HP would be consumed by rudder drag,
> since the rudder would have to be nearly 45 degrees to keep the boat going
> straight.. *Also, the 5 knots mentioned is probably not terribly accurate,
> since the accuracy of a power boat's "speedometer" is not very good at low
> speeds.
>
> >It hurts my head to think about what parts of the two engines were
> >common, and which were different.
>
> Not that bad, I think. *Camshaft, crankshaft, oil pump, water pump, harmonic
> ballancer, distributor, alternator.
>
> _ Jim in NC

The notion of that O'Day hull on the plane scares me! There was no
plane as such on mine, it would have to be balanced on its centerline
somehow! Digging deep into memory I seem to remember speed increases
as power to the 1/4 power after a displacement hull is around hull
speed, trying to climb its bow wave. I think that also represents the
'kick' in power it takes a planing hull to get on its step. Hmm,
aviation link. Maybe sea planes?

There was talk a couple of decades ago about some airplanes getting on
their step, the idea might have been to getting past the desired
cruise speed then slowing down would lead to a more efficient AoA,
rather than doing what most of us do coming out of a climb -- just
accelerate to cruise, trim things up, then sit back and manage the
airplane.

I'm not sure, re common parts of an engine, that the alternator needs
to be different. I think they'd work either way, the rectifiers
wouldn't care about the phase of the AC at their input. You probably
meant to type fuel pump.

[Morgans[_2_]]

"a" > wrote

>The notion of that O'Day hull on the plane scares me!

I did get it surfing down the face of some waves (6 to 8 footers on Lake
Erie) running before a pretty strong wind. It was... fun, I think? <g>
Seriously, I saw nearly 10 knots a few times, so I guess I was planning!
The steering was seriously skittish!

> Digging deep into memory I seem to remember speed increases
as power to the 1/4 power after a displacement hull is around hull
speed, trying to climb its bow wave. I think that also represents the
'kick' in power it takes a planing hull to get on its step. Hmm,
aviation link. Maybe sea planes?

Yep, that sounds about right. And the step in the hull on seaplanes is to
help with the power required to get up on plane, I believe, and to make
rotation less problematic.

>There was talk a couple of decades ago about some airplanes getting on
their step, the idea might have been to getting past the desired
cruise speed then slowing down would lead to a more efficient AoA,
rather than doing what most of us do coming out of a climb -- just
accelerate to cruise, trim things up, then sit back and manage the
airplane.

I have read those articles, or some of them, and the concensus was (as I
recall) that if you had not gone higher, and accellerated by diving those
few feet, the speed it settled on after a few minutes was the same in both
cases.

>I'm not sure, re common parts of an engine, that the alternator needs
to be different. I think they'd work either way, the rectifiers
wouldn't care about the phase of the AC at their input. You probably
meant to type fuel pump.

I think the cooling fins need to be reversed on some alternators, from what
I recall. The fuel pump would be the same if it is a cam actuated one,
wouldn't it?
--
Jim in NC

[[email protected]]

On Nov 15, 4:30 pm, "Morgans" > wrote:
> >I'm not sure, re common parts of an engine, that the alternator needs
>
> to be different. I think they'd work either way, the rectifiers
> wouldn't care about the phase of the AC at their input. You probably
> meant to type fuel pump.
>
> I think the cooling fins need to be reversed on some alternators, from what
> I recall. The fuel pump would be the same if it is a cam actuated one,
> wouldn't it?
> --
> Jim in NC

Alternators don't care which way they turn. I had a 283 in a
small boat, and there was no room for the usual side-mounting of the
alternator. I turned it around and mounted it in front of the engine,
making it spin the other way. I went to the junkyard and found an
alternator fan that had its fins mounted radially rather than at a
tangent, so it sucked air through the alternator equally well in
either direction.

A cam-driven fuel pump isn't going to care which direction the cam
is turning, either.

Dan

[Jon Woellhaf]

Why would an alternator care which direction it turns?

>>It hurts my head to think about what parts of the two engines were
>>common, and which were different.
>
> Not that bad, I think. Camshaft, crankshaft, oil pump, water pump,
> harmonic ballancer, distributor, alternator.

[Jon Woellhaf]

Never mind ... should have read the entire thread before posting. My bad.

"Jon Woellhaf" > wrote in message
...
> Why would an alternator care which direction it turns?
>
>>>It hurts my head to think about what parts of the two engines were
>>>common, and which were different.
>>
>> Not that bad, I think. Camshaft, crankshaft, oil pump, water pump,
>> harmonic ballancer, distributor, alternator.
>
>