Propulsion question (featured on History Channel)

[justinDesign]

I have just watched an episode of modern marvels on the History Channel the subject of which was “Worlds Strongest.” The featured a tug boat with a kind of propulsion system situated under the tug to produce thrust in a certain direction. This propulsion system consisted of 5 or so vertical blades that moved in a circular direction but also moved independently to provide left/right thrust for the tug. I am wondering who manufactures these engines and would appreciate any other information on how they work. Thanks

[SteamFreak]

any propertary name for this system?

[Greybarn]

I think they are called Voith Schneider Propellers. They have the advantage that you do not have to slow the engine down to change the thrust (forward or aft). In fact they have infinitely variable thrust direction and force which is achieved by varying the angle of attack on the vertical blade as it spins around the horizontal disc.

[Guillermo]

Yeap. Voith Schneider. For tugs it's called Voith Water Tractor. Have a look at:
http://www.voithturbo.com/vt_en_pua_...spropeller.htm
Cheers

[SteamFreak]

cool.. I'd love to see it in action live.

[FAST FRED]

I'd love to see it in action live."

You will have to go to a port with thicker water than Galveston .

FAST FRED"

[tom28571]

Some of our ferries in NC use this system and we are known for thin water. Of course they don't stray very far from known water. One great thing is that the ferries don't have to turn around at the terminals, just go in whichever direction is needed. That lops off a significant amount of time on each river crossing.

[kerosene]

http://en.wikipedia.org/wiki/Voith-Schneider