efficienty of paddles

[andy]

Hi,

I read in a website, that the system of paddle wheels is more efficient than propellers. But propellers are preferred because they are not as expensive and cannot be damaged as wheels. Who knows more or knows a study about this theme?

My opinion is, that paddle wheels are very good with slow steam engines with big torques, but not with diesel engines and all these kind of reducing the revs.

Andreas

[Red_Hamish]

Hello Andy, you've touched on a subject which s often reffered to and can be discussed at length. A short answer is to have a look at this old thread and somethings may become clearer.

http://www.paddleducks.co.uk/smf/index.php?topic=1178.0

cheers

Jim

[Bierjunge]

Another olf thread worth recommending is http://www.paddleducks.co.uk/smf/index.php?topic=2506 where some formulae for calculation of efficiency are given.
Moritz

[claudiu_ne2000]

if you tide up from the stern a paddle tug with a propeller tug...and both of them runs on full ahead...the propeller tug will toe the paddler.

I saw on discovery channel...

[kno3]

I've read both threads and while they go deep into paddlewheel design, there is no direct comparison of efficiency of paddlewheels vs. propellers. Anybody knows of such comparisons?
Why is it that paddlewheel tugs survived (with Diesel engines) until the 1960's? They must have had some advantages over propeller powered tugs? Perhaps maneuverability?

[claudiu_ne2000]

a paddle ship has a low depth, so it can get in low waters, without the risk of blocking on the mud, river sand banks or on the aquatic vegetation, a propeller ship needs clean waters.


  most of the paddle ships have flat keel, and a depth of 0,80 m - 1,50 m ideal for low waters

[Red_Hamish]

Hello all, taken from Wikipedia.org a description that I'd seen before;

History of ship and submarine screw propellers
 
Propeller on a modern mid-sized merchant vesselJames Watt of Scotland is generally credited with applying the first screw propeller to an engine, an early steam engine, beginning the use of an hydrodynamic screw for propulsion.

Mechanical ship propulsion began with the steam ship. The first successful ship of this type is a matter of debate; candidate inventors of the 18th century include William Symington, the Marquis de Jouffroy, John Fitch and Robert Fulton, however William Symington's ship the Charlotte Dundas is regarded as the world's "first practical steamboat". Paddlewheels as the main motive source became standard on these early vessels (see Paddle steamer). Robert Fulton had tested, and rejected, the screw propeller.


To read more   http://en.wikipedia.org/wiki/Propeller

cheers

Jim

[andy]

I spoke with a Captain here at the Ammersee, who always drives the new paddlers HERRSCHING and DIESSEN. he told me, that the paddlers are running better straight forward in comparison to the propelled ships. There he always has to correct by the steering wheel, but not at the paddlers. Here he can sit in the wheelhouse and leave the steering wheel out of his hands if he wants.

The survival of the paddle tugs I think can be caused by their torque and their turning point more midship than a propelled tug??

Andreas