Paddleducks
Old Yahoo Group => Yahoo Messages => Topic started by: mgbgtgrimm on June 20, 2005, 07:16:25 AM
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I would like to question the fact that the plastic Sirius kits show
24 paddles per wheel where as the Spratt book calls for 12 paddles
per wheel and the Stiengraeber model use 12 paddles. I don't think
that 24 paddles would work in actual fact, being too close together
to be able to create enough thrust upon entering the water. Just
sitting here observing both models and envisioning the paddles hit
the water I don't think the 24 would work at all. It would create a
lot of turbulence but not much thrust. Anybody have any thoughts on
this. I built my Heller blindly following the as cast plastic paddle
wheels but I am going to buid one of the Russian versions by
correcting this to have only 12 paddles. Greg & Grimm
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Darn it, G&G.. I forgot to mention that last week..virtually every
reference I've checked refers to 12 radial floats (blades) on
Sirius. If you didn't permanently glue in the wheels on the plastic
model you might be able to take them off and modify them or make
another set...or just leave 'em the way they are..the model still
looks pretty!
So far as 24 floats working less effectively? ...They would probably
be fine depending on the rotation speed. Some of the early paddlers
rotated very slowly and had numerous paddles. Paddle wheel efficiency
is a balance between rotation speed (RPM), blade (bucket) area/shape,
immersion depth and (on a sidewheeler) degree of roll. They all have
to fly together to make them efficient. In real life paddlers (and
many believe in models too) the greatest single innovation to paddler
efficiency was the feathering blade which you hear lots about on this
channel!
Sirius started off much slower in speed than "Great Western" but was
able to greatly improve her speed towards the end of her voyage as
her weight reduced (they even burnt the furniture to keep her boiler
going!)and her paddles became less immersed into the water, or at
least that's what historians tell us!
A lovely drawing I have of "Sirius" is accompanied by a caption which
clearly states she had 12 bladed wheels but shows 18! "Great Western"
has 20 bladed wheels while "Britannia" (1840) had 21 and "Adriatic"
(1856) had 32!
American paddlers always have had more blades and larger, slower
revving wheels than their British counterparts. To me the British
ships have always seemed totally preoccupied with speed rather than
capacity and their seven bladed high revving feathering blades attest
to it. It seems strange that, of all the vessels I have researched,
hardly any American ships used the feathering blade..it was very much
a European thing and VERY efficient it seems! I wonder why the
Americans didn't favour it too?
PJ
Victoria, BC Canada
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I am surprised at the statement that hardly any Americans used the feathering wheel. Almost every Great Lakes paddler from about 1880 on used them, and that was true of the eastern coastal and river steamers as well. They were not used on the Mississippi. I'm no Mississippi expert, but I believe that was because there were so many logs, etc, in the water that feathering wheels were just too delicate. So the Mississippi steamers continued to use big-diameter fixed-bucket wheels, while the deeper-water steamers went to smaller-diameter feathering wheels. There were a few exceptions; the big railroad ferries at Detroit, for example, continued to use large-diameter wheels with fixed buckets because they broke ice in the winter. The improvement in efficiency of the feathering wheel is considerable; the steamer City of Detroit of 1878 was built with large-diameter wheels with fixed buckets; her near-sister City of Cleveland of 1880 had feathering wheels and within a couple of years
the City of Detroit was converted to feathering wheels. Consider that this meant lowering the crankshaft in the ship because the wheels were of smaller diameter. That means major alterations to the engine frame, a new connecting rod, new wheels, etc. That much money into an alteration of vessel that was running well is an indicator of the increased efficiency of feathering wheels.
There were other benefits on a passenger steamer, especially one with cabins in which passengers slept; feathering wheels are quieter and produce less vibration.
Bill Worden
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Bill...of course you're ABSOLUTELY right and I have no idea why I
should have made such a silly statement... must be the unseasonal
freezing temperatures here addling my brain! There are so MANY
examples of feathering wheels on Great Lakes, Hudson River Steamers
etc...my mind was stuck in the 1850's..I should know better!
Apologies for my misleading statement. Thanks for keeping us honest!!!
Best regards
PJ
Victoria, BC Canada
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Paul-
What is true is that North America was slow to adopt feathering wheels, long after they had shown their worth in Europe. So for the 1850s and 1860s you're right on; they were out there, but no one used them. As I recall, they first appeared in North America on Canadian steamers on the St.Lawrence, where British influence would have been considerable. Just as with the wheels, we loved the beam engine and were slow to adopt the inclined engine with its considerable advantages in keeping weight low, etc. Interestingly, we weren't particularly backward, I don't think, in propeller technology. I wonder if "keep it simple and keep it cheap" was the root of the beam engine/big wheel long after we saw what newer technology could do.
Bill
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Bill you said a mouthful there! As a newbie to paddleboats and
relatively new to modelling tugs I've been struck time and again by
the differences between English and American 'tugnology'.
Your observation about late adoption of inclined engines and the
feathering wheels is fascinating.
But there seem to be many more differences than this. Where the
English tugs have busy general arrangements, the American general
arrangements for decks seem spartan in comparison. Where the English
tugs use towhooks mounted on tables, American tugs favour samson
posts ... or pushing instead of towing, for that matter.
Given the early history of conflict between UK and USA do you think
that the divergence of working boat design may have been motivated as
much by rebellious US contrarians as slow adoption?
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Well, I've actually done a lot of tugboating, and there are certainly differences. On the other hand, there are significant differences from Britain to the continent as well; note Alistair's recent reference to sternwheel paddle towboats on the Danube and Elbe. Or consider the magnificent big sidewheel tugs on the Rhine and Danube. Of course, Britain lacks really lengthy rivers like the Rhine or the Mississippi, so long-distance towing for freight movement would not really be an issue there.
I think one big factor would have been the relative sophistication of British technology and manufacturing. That's the motherland of the Industrial Revolution, after all. It may simply be that British workmen, machines, and plants were better able to handle the complications of something like an oscillating engine. Whatever the drawbacks of the beam engine (major topside weight, push-pause cycle) it was simple and dependable. Many people don't realize that later beam engines were sometimes compound; the engineers saw the fuel efficiancy of comppunding, but instead of building oscillators or inclined compounds they compounded beam engines, some of them as retrofit. That's complicated because the second cylinder has a different stroke from the first, being closer to the pivot of the beam....
I think issues like towbits/hooks are largely regional/national. Even if a Brit emigrated and started to work on tugs here, he'd just see that it worked fine and not worry much about it. The bits are, I suspect, the earlier type, evolving from vertical timbers. And British tugs are not more different from American tugs than British passenger paddle steamers are different from ours!
I must admit, I've never seen a British tug tow by pushing "on the hip," but on reflection, it seems to me that almost all the tugs I've seen in Britain were doing ship handling and not barge towing. And, once again, the issue of the Mississippi-type pusher towboat operation wouldn't arise in Britain because of those geographical differences.
And I really don't think that there was avoidance of British technology on grounds of political disagreement; the fact is that the two countries came to terms shortly after the War of 1812, and 19th century America was heavily British in character and orientation. There was certainly a desire to compete, but that would have advanced technology, not slowed it.
Bill