The Voith Schneider Propeller
August 7, 2014 2:03 PM   Subscribe

The Voith Schneider propeller is a unique marine propulsion system that uses vertical rotating blades to allow for high maneuverability. If you can't stomach the full promotional video (skip to here to see how it works), watch it in action underwater, or give it a test drive with an interactive VSP simulator.
posted by dephlogisticated (20 comments total) 10 users marked this as a favorite
Woot! I discovered this mechanism a few years ago and had a little geekout. It's been tried (without great success) for helicopters and wind/hydro/tidal turbines [pdf] too!
posted by Popular Ethics at 2:14 PM on August 7, 2014

Lego version here.
posted by Confess, Fletch at 2:15 PM on August 7, 2014 [2 favorites]

But shouldn't I be able to make it go sideways? Why won't it go sideways?
posted by ckape at 2:15 PM on August 7, 2014

The keelboard prevents it from going sideways, I think.
posted by Keith Talent at 2:18 PM on August 7, 2014

There's a terrestrial wheel that has some similar capabilities. The video shows them on forklifts, but I've only ever seen them employed on airplane loading luggage lifts. (the lift has the powered wheels on the top, and the luggage boxes just get moved around on top of them)
posted by aubilenon at 2:21 PM on August 7, 2014 [1 favorite]

Actually, I think it won't let me go sideways because there are actually two propellers that have their controls hooked together, and without independent control there's no way to allow both turning and sideways movement. The keel probably doesn't help, though.
posted by ckape at 2:25 PM on August 7, 2014

aubilenon - I've seen those too, they're called "Mecanum" wheels, and they're popular with robotics. Your link has lit an idea bulb though: I wonder how a voith-schneider propeller with wheels mounted on the tips of the blades would perform.... brb :)
posted by Popular Ethics at 2:27 PM on August 7, 2014

Wait, I thought these were Blade Runner guys. What is this witchcraft?!?
posted by JoeZydeco at 2:36 PM on August 7, 2014

Of course, the main problem with this is how many moving parts it has, which are all underwater.

A traditional prop is preppy much a drive shaft and fixed blades. Unless you sheer off the part of the prop that is external to the hull, you can do a lot of repair work directly on the boat without having to put it into dry dock to perform repairs or maintenance.

Of course, you could build a boat hull system that might allow you to retract the propeller up into the hull for repair and maintenance, though then you are basically dealing with a boat with a hole in the bottom of it, instead of a sealed substructure and housing for your main propulsion system.

It definitely offers more maneuverability over traditional prop systems, but given the increased cost and number of parts that could break, I don't think that trade off will be worth it.

Though I'd love to be wrong.
posted by daq at 2:53 PM on August 7, 2014 [1 favorite]

It reminds me of the heady days of Sputnik and Yuri Gagarin when the world trembled at the sound of our rockets. Now they will tremble again -- at the sound of our silence.

posted by RobotVoodooPower at 3:00 PM on August 7, 2014 [4 favorites]

daq beat me to posting....My first thought (after "Cool!") was "Hmmm, that's an awful lot of fiddly bits exposed to water."
posted by Greg_Ace at 3:11 PM on August 7, 2014

Apparently despite the moving parts, wikipedia claims they're in reasonably wide use in tugboats and ferries. Which both seem like applications where frequent maintenance wouldn't be particularly impractical.

The big question is does anybody make and sell Voith Schneider propeller beanies?
posted by aubilenon at 3:34 PM on August 7, 2014 [2 favorites]

The current Woolwich ferries in London are 50 years old in daily service and use Voith-Schneider propulsion, so it seems robust enough for that.
posted by ambrosen at 3:43 PM on August 7, 2014 [1 favorite]

Why won't it go sideways?

If you click on the "Hydrodynamics Forces" view, you can see it's possible to get a net thrust vector that's perfectly perpendicular to the axis of the ship. But such a vector doesn't align with the center of the prop itself; in fact, its position varies with its size and direction. Even if you built the ship in such a way that a perfectly starboard-facing thrust vector pushed the ship to port, the port-facing counterpart vector would be closer to the bow and would be expected to make the ship turn to starboard.
posted by Western Infidels at 4:07 PM on August 7, 2014

That's why you need like 75 of these suckers sticking out of every part of your hull!
posted by aubilenon at 4:13 PM on August 7, 2014

76. You want to make sure the torques all even out.
posted by ckape at 4:18 PM on August 7, 2014

Nah, I don't care what happens, really
posted by aubilenon at 4:19 PM on August 7, 2014

Propeller? Man, impellers are where it's at!
posted by TedW at 4:36 PM on August 7, 2014 [1 favorite]

Impellers are pretty great. The newer (and larger) passenger ferries from Vallejo to SF mount impellers instead of propellers and scoot across the bay at 38 knots. They also dock in a jiffy — the pilot just pulls up next to the dock and shoves the boat up against it by directing the thrust out the other side. If only they'd replace the older boats running the Oakland service I commute on daily...
posted by spitefulcrow at 7:53 PM on August 7, 2014

Actually you could build a well inside the hull hosting the propeller (Basically you weld a large pipe on the hull inside the boat).
If you build it so that the top of the well is over the water line , you could just pull up the complete contraption into the whell for cleaning / repairing.
The advantage of this system is clearly in situation where time = money. A tug that is quicker and more precise thanks to this system will save money even if it cost more in mainteinance / building.
I regulary dock a former tug which has 1 huge propeller and no side thruster and boy do I sometime wish I could just move that beast sideways. Add wind and kids running around on deck while docking to make it more interesting.
posted by elcapitano at 1:16 AM on August 8, 2014 [2 favorites]

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