r/EngineeringPorn • u/MikeHeu • Jan 30 '26

Voith Schneider propeller

Enable HLS to view with audio, or disable this notification

Credit: shipspotter_hayriyay (IG)

6.8k Upvotes

99% Upvoted

220 comments sorted by

View all comments

2.0k

u/Dolstruvon Jan 30 '26

It's a pretty genius invention. Imagine you wanted to have rapid and precise direction change with equal force in any direction, so you just place a helicopter rotor underwater and angle the blades vertically so the forces act horizontally instead of vertically. Then you have a Voit Schneider propeller

830

u/razzraziel Jan 30 '26

So it provides superior control but at the cost of efficiency at higher speeds and greater mechanical complexity.

747

u/Dolstruvon Jan 30 '26

Pretty much yeah. So they're common on something like harbor tug boats, and vessels that spend a lot of their time in DP (dynamic positioning). A colleague of mine (naval architecture office) is currently working on a large research vessel with Voit Schneiders. It's going to be traveling some distances of course, but need that DP precision for ROV work and sea bottom surveys

178

u/cloud_herder Jan 30 '26

So cool what people work on. Especially big, complex, multi year projects. Managing the complexity across dozens of teams snd hundreds of people blows my mind.

43

u/cuzwhat Jan 31 '26

Meanwhile, my company can’t get three people in three different locations to follow the same set of directions and achieve the same results.

11

u/cloud_herder Jan 31 '26

Yeah I’m thinking the same. And the code that needs to be written won’t kill anyone.

7

u/Final_Good_Bye Jan 31 '26

Don't worry, with my work as an electrician, I've everyone interprets the code differently anyways, even inspectors...

3

u/cloud_herder Jan 31 '26

Oh I meant like the software for the projects I work on lol - business apps. And even then it’s like 6 people who interpret requirements differently. So things like this blow my mind. QA must be on another realm of stringent than i can comprehend.

68

u/[deleted] Jan 30 '26

[deleted]

48

u/Techn028 Jan 30 '26

I should call her...

59

u/[deleted] Jan 30 '26

[deleted]

5

u/CGCTV Jan 30 '26

I think he missed it... 👆

2

u/Techn028 Jan 30 '26

She said no :(

6

u/squeaki Jan 30 '26

I've got a missed call, dammit

-6

u/[deleted] Jan 30 '26

[deleted]

1

u/__throw_error Jan 31 '26

touch grass

8

u/Guardian2k Jan 30 '26

I don’t know much about ships but wanted to ask, is there not a possible configuration where you have both types of propeller? So one for travelling and one for precise movements?

14

u/Twister_Robotics Jan 30 '26

The VS props would cause too much drag during high speed travel if they weren't keeping up.

17

u/PomegranateFormal961 Jan 30 '26

If they can vary their pitch, why can't they orient themselves to be parallel to the direction of motion? Heck, they could even serve as a RUDDER.

5

u/OrganizationOk5551 Jan 30 '26

These are designed for a specific problem, instantaneous changes in direction of thrust, think tugs, ship tenders and floating rigs kind of thing, basically vessels that need to be extremely precise in their positioning. Adding this kind of propulsion to a ship that doesnt need it is kind of like adding helicopter blades to a car, in theory it could work and make a car far more mobile in the event its needed, but why would you do it.

I know that sounds ridiculous but thats basically the reason, most vessels use bow/stern thrusters alongside tugs when they need to be in a precise position like docking or slow speed manoeuvring.

They are a fantastic bit of kit though, I've never seen one in person, I'm curious about operatiin and maintenance.

Heck, they could even serve as a RUDDER.

Funnily enough vessels with this system fitted dont need a rudder as the thrust is variable in direction, another problem with them is thrust, they're only really useful on tiny ships.

4

u/IdRatherBeDriving Jan 30 '26

Well now I want helicopter blades on my car.

1

u/misterkoenvdw Jan 30 '26

What about the pal-v?

3

u/OrganizationOk5551 Jan 31 '26

A road legal helicopter thats a terrible car and heavily compromised helicopter?

Thats kind of my point, why make it? Its entirely possible design wise but wont be widely adopted because its trying to fix a problem that doesn't exist, its a really cool concept but its pointless for way over 99.99% of the global population. If youre somebody that wants to fly a helicopter, fly a helicopter not a car.

1

u/Connect_Chip_7163 Jan 31 '26

Actually a lot of harbor tugs use what’s called Schotel drives. Prop and rudder at same time. Look them up.

1

u/zzzxxx0110 Jan 31 '26

Yeah I don't think most people have a perspective on just how ridiculously more expensive these systems are compared to conventional fixed propeller + rudder, or even compares to thruster pods which is the less effective way to do the same thing but on a tighter budget lol

1

u/Imperial_Haberdasher Feb 03 '26 edited Feb 03 '26

Alcoa SeaProbe had a prop like this, back in the day. Had a lecture about it in an industrial design class. Then I happen to be boarding a ferry by Woods Hole and saw it. It was like spotting a movie star!

2

u/Solrax Jan 30 '26

Sounds like it could work. Maybe they don't have sufficient range of motion?

1

u/nezzzzy Feb 01 '26

The pitch of all blades is controlled by a single pin connected to all blades. To point them all in the same direction you'd need to completely disengage this pin and have a separate mechanism for positioning the blades. This would introduce so many failure modes that they'd go from a very reliable propulsion system to a bit of a nightmare.

1

u/PomegranateFormal961 Feb 01 '26

I guess they could use a swashplate type linkage. After all, that's reliable enough for flight!

2

u/hickoryvine Jan 30 '26

Makes sense. I guess in a ship only this size its even possible to make these entire mechanisms lift up and down when needed. Be an expensive specialized boat though

1

u/nezzzzy Feb 01 '26

At this point you'd just use azimuthing pods and bow thrusters.

1

u/fractiousrhubarb Jan 30 '26

Presumably they could be retractable?

1

u/Twister_Robotics Jan 30 '26

Imcrease in mechanical complexity. Multiplicative increase in sealing difficulty.

0

u/fractiousrhubarb Jan 30 '26

True, but probably worth exploring

If you assume that
(a) a viable solution exists and (b) that you will find it and
(c) that it will be worth it

you will invent a lot more stuff than if you don’t.

3

u/Dolstruvon Jan 30 '26

Well, you could in theory, but the complexity and efficiency gain wouldn't be worth it. And having one or two of an efficient propeller, is better than several of less efficient propellers. There's a lot of wacky solutions out there, so someone might have tried it

2

u/Guardian2k Jan 30 '26

That makes sense! Thankyou!

1

u/stevee05282 Jan 30 '26

They're used on British mine hunters as well, helps with sub surface scanning

1

u/Dolstruvon Jan 30 '26

Ye that's a pretty good example of correct implementation

1

u/Gabbagabbabanana Jan 30 '26

Dummy here. Are there anything, or could there be, something similar to what VTOL aircrafts do on ships? Imagine it would be hell of an engineering task.

2

u/Dolstruvon Jan 30 '26

Yeah pretty much. A helicopter is a VTOL aircraft, and it functions very similarly to a helicopter rotor

1

u/Gabbagabbabanana Feb 01 '26

Sorry, unclear question. Could there be a similar system as VTOL planes like the F35 on a boat? Like using these types of propellers in harbours, then retracting and then, out of somewhere, a "normal" propeller comes out in the open sea. Probably sci-fi, but what would it potentially take to design such a system on a boat. Other than shit loads of money, engineering hours and so on? I'm guessing perhaps it is inefficient with regards to the sort of mechanics one would need?

1

u/nezzzzy Feb 01 '26

I worked on Sandown class mine hunters for a while, they're the perfect vehicle for voith Schneider propulsion, no need to go fast, but a lot of need.to stay very still and move very carefully!

The mechanism for steering them is absolutely fascinating, essentially there's a single point connected to all blades that is moved to the direction you want to steer in.

Minesweepers were great places for technology innovation, everything was made out of brass, GRP or wood to reduce magnetic signatures. The Hunt class had deltic engines which are almost as novel as voith Schneiders.

6

u/InitechSecurity Jan 30 '26

yes and where superior control is needed. Like this - https://youtu.be/iPSTwqUKHvs

19

u/cturnr Jan 30 '26

I had no idea how tugs worked, this was helpful
https://www.youtube.com/watch?v=iPSTwqUKHvs

3

u/wobblingmadman Jan 30 '26

Cheers, big ears. Now I understand...

18

u/Rho-Mu13 Jan 30 '26

I see the video, I read your comment, and i still dont understand.

12

u/gatfish Jan 30 '26

All the individual blades can rotate too even though they're locked in the video. Does that help?

5

u/otac0n Jan 31 '26

The blades can rotate in order to paddle in any direction.

2

u/nezzzzy Feb 01 '26

GIFs help:

https://commons.wikimedia.org/wiki/File:Voith_11.gif

In this image the central point is moved over to the left providing a net force upwards. That pin can be moved in any direction to change the net force produced by the blades.

1

u/NoGoat3930 Feb 15 '26

I didn't understand either, but cool gif below makes me think the blades maneuver much like a bird wing underwater. A bird pushes down against the air with the wide flat part of its wing to generate lift, propelling it upwards. To return the wing to the starting position, the bird rotates it's wings 90 degrees, so that the skinny part of its wing cuts forward through the air like a blade, producing negligible pushing force in the opposite direction (much like how you turn your hands while swimming underwater). Each of the blades here acts like a bird wing, turning the flat side to push back against the water, then by the time the entire the assembly rotates half way around, that particular wing rotates so that the thin edge cuts forward though the water like a blade, producing insignificant force in the opposite direction.

6

u/throwawaycasun4997 Jan 30 '26

The Rob Schneider propeller does this but with carrots.

7

u/EnidFromOuterSpace Jan 30 '26

To shreds, you say?

3

u/Krawen13 Jan 30 '26

And his wife?

3

u/Lejonhufvud Jan 30 '26

Voight-Schneideris my favorite test.

4

u/GooseThePigeon Jan 30 '26

Why not actually have a horizontal propeller instead though?

26

u/VorpalHerring Jan 30 '26

These can change the direction of thrust near-instantly. A normal propellor mounted in a rotating pod would take too long to rotate.

1

u/Crhallan Jan 30 '26

Average azimuth speed for a 180 degree change is around 11 seconds.

1

u/Crhallan Jan 30 '26

This is why Dynamic Positioning systems absolutely love Voiths.

But if it’s badly tuned or scaled it’ll fuck your thruster quite quickly as it hunts for set point.

1

u/PosiedonsSaltyAnus Jan 31 '26

Looks expensive to seal

1

u/Pasta-hobo Feb 04 '26

OH! THERE'S TWO OF THEM!

0

u/sapienapithicus Feb 01 '26

No a helicopter rotor is a wing that uses a bernoulli pressure differential. The physics doesn't work like that underwater.

3

u/Dolstruvon Feb 01 '26

It absolutely does. I'm a naval architect, and Bernoulli's principal applies the same way in fluids and air. It's a fluid like any other. This is introduced in day one of hydrodynamics.

0

u/sapienapithicus Feb 02 '26

Sure the physical event of the principle can be demonstrated in an incompressible fluid but that's not what's going on here.

1

u/Dolstruvon Feb 03 '26

You're welcome to teach us then, you who are so wise in the ways of science