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-   -   Vane propellers (http://www.steamboats.org/forum/steamboats-history/897-vane-propellers.html)

Alan Bates 01-12-2007 11:36 AM

Vane propellers
 
Someone asked about vane drives. I found my copy of a paper on the subject, while looking for something else, naturally. The paper is titled The Design and Construction of Small Craft, by R. Munro Smith, A.M.I.N.A., published by the Technical Section, Associates of Engineering and Shipbuilding Draughtsmen, 96 St. George's Square, Westminster, London, 1924

As I explained, in part, the propellers were three-bladed, crude triangles. The shafts were above the waterline and only the vanes at the bottom impinged against the water. The propellers were 11 feet in diameter and had a pitch of 16 feet. The design rotary speed was 66 rpm. The area of water acted upon at full speed was 59.28 sq ft. Shaft horsepower was 116.

Comments were as follows: The vane wheels do not require immersed struts or supports. Every portion of the immersed blade is acting efficiently during its passage through the water. High propulsive efficiency in relation to all o0ther known methods of propulsion. Great maneuvering powers. Effective variation of water acted upon with variations of draft. Higher revolutions per minute than paddlewheels and less weight of machinery. Compared to sidewheelers, overall width is reduced. The vanes are stronger than paddlewheels.

I do not know why such a wonderful system failed to be adopted, but I suspect that using only part of the wheels in the water represented about a 60% loss in efficiency compared to a fully immersed propeller. Other devices, such as the tunnel stern and the Kort nozzle did utilize all of the wheel blade area to do work. In any event, this experimental boat was probably the only one ever built.

R. Dale Flick 01-12-2007 11:57 AM

Hi, Alan & steamboat colleagues:
Thanks for the detailed information on 'vane propellers.' It was referenced in a posting Re: building the DELTA KING/DELTA QUEEN. DENNY BROS. in Scotland made the proposal to the C.T. Co., Jim Burns and Capt. Anderson in the initial discussions and plans for the two boats. It never flew with them and, contrary to Jim Burns sounding concerns, C.T. Co. stuck with conventional steam propulsion and sternwheel. They 'stuck with what they new.' Capt. Anderson was a 'Commodore' in his own right for sure. I'd never heard of such a system until I read it in these old documents and letters. Nothing new under the sun, mind you, just buried for a long time.

Cheers,
R. Dale Flick

Michael Gillespie 01-13-2007 01:38 PM

During the War Between the States, Commander William D. Porter listed several reasons why propellers were not "practicable" for use on the Western Rivers. One reason was that "the sand in the water cuts away rapidly the journals under water." The vane propeller that Alan describes would have eliminated that problem since the shafts were above the water line.

Porter's other objections, by the way, were that the shallow rivers would not permit a large enough propeller diameter for larger steamers to obtain the necessary speed (relative to the speed of the engines in 1862), and debris in the river frequently broke off the blades. He said that small tugs built for the river fleet had all lost their propellers within three weeks of their launching.

Porter concluded: "I am, therefore, of the opinion that propellers can not be made serviceable in Western waters, for, if they could, the shrewd Western river men would have had them in use."

Alan Bates 01-13-2007 02:21 PM

Wear on propellers in silty water remains a problem today. Shipyards keep a small stock of props on hand for replacement. Everything happens to them that Admiral Porter mentioned even though the "cutless" bearings of today have reduced that problem to a manageable level. The tips of propellers wear into lovely lace patterns. They get bent by hitting obstructions and a heavy log that floats between a prop and a bearing strut can do a lot of damage. Hitting a buoy does them no good.
The vane propeller would be subject to all of these sources of trouble excepting the bearing problem and in addition, I think, would vibrate terribly.

Jim Reising 01-13-2007 08:57 PM

"Wonder when that happened. It didn't happen on my watch". When we pulled our boats out of the water on drydock and discovered the wheels bent, blades missing, and the steering rudder completely gone that's what both the captain and pilot would say. Since nobody hit anything, all I could suppose was there are some mighty strong catfish in the river chewing on the propellers and rudders.

John Fryant 01-13-2007 10:36 PM

Jim, Alan,
Denny Brothers built at least one vane wheel powered tug for use in China. It was built in 1925 for John Swire & Sons Ltd. - the China Navigation Co. and named "Chuchow" and was probably gas or diesel powered. They also built a ferry named Fano. The Chuchow had two four-blade vane wheels at the stern. She was 68 1/2 ft. long with a beam of 14 ft. and a draft of 2 ft. Her engine was 96 shaft HP and the speed was listed at 9 knots at 106 RPM of the vane wheels.

When I was digging through the Ward Engineering Works plans ten years ago I found a drawing done by Dennys for the converson of the towboat Duncan Bruce to Vane wheel power! The drawing is dated 1930 and I have a print of it. Wards probably had Dennys do that proposal when they were having so much trouble with the Bruce's sternwheel drive system. Too bad the project never happened. It would have been interesting to see how the "Drunken Brute" would have preformed with that propulsion system. She would have had four vane wheels at the stern.

I imagine those vane wheels produced about as much side thrust as they did forward thrust.

Alan Bates 01-14-2007 04:46 AM

Then there were at least two vane-driven boats built. The paper I have shows a twin-screw version. The hull was 100' long, 23.5' wide, and the average draft was about 4.6 feet. Dispacement was 186 tons and speed attained was 9 knots. The vanes were driven by leather belts from the engines.


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