6 ms·

Voith Schneider Propeller

140 points by Luc 8mo ago

yccs27 8mo ago
This reads a lot like an advertisement. The linked page [[Cyclorotor]] is more neutral and has more information on the design and applications outside of marine vessels: https://en.wikipedia.org/wiki/Cyclorotor https://en.wikipedia.org/wiki/Cyclorotor
- adolph 8mo ago
  This is conceptually significant because the article links the mechanisms used in watercraft and aircraft.
mkreis 8mo ago
See a tug showing off here: https://www.youtube.com/watch?v=u6uNECa_X8Q https://www.youtube.com/watch?v=u6uNECa_X8Q Voith is the only company producing those, even though the patent has expired.
- dylan604 8mo ago
  Please excuse me while I rock your boat up against the pier unnecessarily as I show how to do burnouts and donuts with my boat for some viral content.
javiramos 8mo ago
The coolest recent development in marine propellers is toroidal propellers which are now commercially available and seem to perform significantly better than standard propellers: https://www.sharrowmarine.com/ https://www.sharrowmarine.com/
- LoganDark 8mo ago
  That website seems to no useful information; only marketing speak about how great it is... Do you know of a good source on how toroidal propellers work and the engineering behind them?
  - LysPJ 8mo ago
    Here you are: https://en.wikipedia.org/wiki/Toroidal_propeller https://en.wikipedia.org/wiki/Toroidal_propeller
    - reedciccio 8mo ago
      Uhm... The article lacks quite a few citations.
    - AftHurrahWinch 8mo ago
      Really enjoyed this: > In the centuries after Archimedes invented the Archimedes' screw, developments of propeller design led to the torus marine propeller... it was invented in the early 1890s "the centuries" indeed. :)
  - HoldOnAMinute 8mo ago
    I didn't even see a picture of the propeller, if there was one. There was a giant, white, blank space.
    - LoganDark 8mo ago
      That space is blank for me too. This page seems to have one halfway-functional photo for me: https://www.sharrowmarine.com/store/p/sharrow-by-veem-ds9sw https://www.sharrowmarine.com/store/p/sharrow-by-veem-ds9sw This URL may work: https://images.squarespace-cdn.com/content/v1/560055b1e4b017b5db4fb31f/3cb717fa-7ac5-4529-9262-818416e86e4f/9+-+SHARROW+by+VEEM.png https://images.squarespace-cdn.com/content/v1/560055b1e4b017...
      - dylan604 8mo ago
        If that's machined, that's impressive. I've seen some crazy 5-axis CNC examples, and it's usually some bladed turbine fan. Not sure how many axis (axii??) this would require, but it looks cool nonetheless.
        8mo ago
- brk 8mo ago
  For the most part the Sharrow props have not proven to be much of an improvement, particularly for the high price. The tests that have shown "significant" improvements have frequently compared the Sharrow to a sub-optimal prop. Feedback from many actual users is that the gains are moderate over a narrow RPM range.
  - closewith 8mo ago
    And much harder to repair.
  - jcgrillo 8mo ago
    Do you have any more information/sources to share on this? I have an Eastern 18 powered with a Yamaha 60hp 4 stroke and I've been struggling to dial the prop right. I don't know off the top of my head what the specs of my current prop are but basically I feel like I'm not taking advantage of the engine's torque at less than WOT, so I basically just run it flat out. If I could extract just a little more thrust out of the prop at lower RPMs it feels like the engine would have enough grunt to make the boat plane in the mid-high 4000s instead of 5000-5200rpm where I currently run it. Ideally, given the bsfc/hp curves, I'd like to run the engine at a bit lower RPM, but the way it's currently set up at ~4600rpm it's not fully up on the step. I was (perhaps wishfully) thinking a little more efficient prop design might help. The other thing I was thinking of trying is swapping in a different "high torque" lower unit with a lower gear ratio and running a significantly larger prop.
    - brk 8mo ago
      Sources are primarily boating forums, dockside conversations, etc. In theory your boat in right in the sweet spot of recommended power range at 60HP. I don't know all the background on it, so all kinds of potential problems, but I would wager that "propped wrong" is unlikely to be the core culprit. I'd start by getting it weighed and comparing your loaded weight to manufacturer specs. USCG requires positive buoyancy for hulls under 20'. This is typically achieved with using expanding foam in hull cavities, and that foam can have a tendency to absorb and hold water if the boat develops any failure of the seals around the bilge areas that are foamed. Reports of poor performance are very common for these sub 20' hulls because of waterlogging. If not a waterlogged hull, you might also just have too much stuff on-board. To a lesser degree, a bimini can also have an adverse affect on speed/planing, if it's acting like a parachute. Not sure if you have a bimini, but if so it's worth trying a run with it up vs. down. I'd also look at how your outboard is mounted. It's not clear if it the outboard from the factory, or if the boat has been repowered. Outboards being too high, too low, etc. are pretty common issues that can also majorly impact performance. That's a few thoughts that comes to mind off-hand.
- HPsquared 8mo ago
  That's pretty cool, but I wonder if they can get stuff tangled in there.
martinclayton 8mo ago
See also https://news.ycombinator.com/item?id=26339421 https://news.ycombinator.com/item?id=26339421
xpe 8mo ago
I recommend this video with animations : https://www.youtube.com/watch?v=QrBF9BWYAZY https://www.youtube.com/watch?v=QrBF9BWYAZY
xpe 8mo ago
From a resilience POV, my guess would be that failure of any one blade would botch the system overall. Maybe that is why many diagrams show them installed in pairs. (I would guess each operates in a different direction for angular momentum reasons.) I have no idea about overall reliability.
- brk 8mo ago
  For marine applications dual drives are common as it enables better rotational control for maneuvering. The redundancy aspect is also a factor, but moreso for applications where you are going to be far from shore. For tugboat and ferry type applications, where these drives are most common, that is less of a concern.
- w4der 8mo ago
  They are installed in pairs and work together with bow thrusters to allow for dynamic positioning, the RV Falkor (too) has them for this reason.
- somat 8mo ago
  I think you are right, One only provides directional thrust, a pair would be needed for rotational thrust. Most traditional tugs have a pair of screws for just this reason. Not so much to turn but by applying differential thrust they can pull sideways. A vector drive like this will vastly increase the envelope of possible pull conditions.
oliwary 8mo ago
Cool, similar to helicopters which can also control direction indepentendent of thrust, which leads to RC helicopters being able to pull of crazy, physics-defying moves like here: https://www.youtube.com/watch?v=QSiwyoQldfo https://www.youtube.com/watch?v=QSiwyoQldfo
- _aavaa_ 8mo ago
  Thanks! I’ll keep this on hand for next time I hear that a UFO proof video comes out saying that an object can’t move the way it does on screen.
  - Someone 8mo ago
    Wing area (roughly) scales by n² and mass by n³, so size matters for this kind of thing. See https://en.wikipedia.org/wiki/On_Being_the_Right_Size https://en.wikipedia.org/wiki/On_Being_the_Right_Size (PDF at https://www.phys.ufl.edu/courses/phy3221/spring10/HaldaneRightSize.pdf https://www.phys.ufl.edu/courses/phy3221/spring10/HaldaneRig...)
- ted_dunning 8mo ago
  That is bizarre and amazing. I have never seen any kind of aircraft that resembled a dragonfly as much as that. The maneuvers are so extreme and come so fast that I would not have been able to say for certain that this wasn't just a very nasty crash in progress. But they were, in fact, completely controlled and intentional. Incredible.
- dylan604 8mo ago
  That's the worst lawnmower I've ever seen. It didn't even cut the grass as much as it just bothered the blades of grass. 0 out of 5 stars. What's that? It's not a mower. Oh, well then, that thing is cool as hell, but not as cool as the pilot that looks like he's just casually standing there.
  - torkal 8mo ago
    This made me chuckle:)
manyturtles 8mo ago
These were used on three car ferries in Scotland, mostly between Gourock and Dunoon but the same vessels were sometimes used on other routes. The Saturn, Juno and Jupiter which were quite fast and incredibly maneuverable: "...service speed was around 15 knots (although she could also achieve 13 knots astern and 3 knots sideways" with just those drives. No separate screws, bow or stern thrusters. Same drive was used on a few smaller local ferries, too. If I remember right what they didn't do was go exactly straight. You could see a (very modest) s-shape in the wake over distance. ref: https://www.shipsofcalmac.co.uk/fleet-features/the-streakers https://www.shipsofcalmac.co.uk/fleet-features/the-streakers
silveira 8mo ago
The same article in german has some nice animations: https://de.wikipedia.org/wiki/Voith-Schneider-Antrieb https://de.wikipedia.org/wiki/Voith-Schneider-Antrieb
crest 8mo ago
They're really useful for tugs and other specialty applications that need the ability to have differential thrust in arbitary directions with lots of thrust at low speed, but loose to Azipods on faster and larger ships.
Keekgette 8mo ago
[flagged]

140 points by Luc 8mo ago

This reads a lot like an advertisement. The linked page [[Cyclorotor]] is more neutral and has more information on the design and applications outside of marine vessels: https://en.wikipedia.org/wiki/Cyclorotor https://en.wikipedia.org/wiki/Cyclorotor

adolph 8mo ago
This is conceptually significant because the article links the mechanisms used in watercraft and aircraft.

mkreis 8mo ago

See a tug showing off here: https://www.youtube.com/watch?v=u6uNECa_X8Q https://www.youtube.com/watch?v=u6uNECa_X8Q Voith is the only company producing those, even though the patent has expired.

dylan604 8mo ago
Please excuse me while I rock your boat up against the pier unnecessarily as I show how to do burnouts and donuts with my boat for some viral content.

javiramos 8mo ago

The coolest recent development in marine propellers is toroidal propellers which are now commercially available and seem to perform significantly better than standard propellers: https://www.sharrowmarine.com/ https://www.sharrowmarine.com/

LoganDark 8mo ago
That website seems to no useful information; only marketing speak about how great it is... Do you know of a good source on how toroidal propellers work and the engineering behind them?
- LysPJ 8mo ago
  Here you are: https://en.wikipedia.org/wiki/Toroidal_propeller https://en.wikipedia.org/wiki/Toroidal_propeller
  - reedciccio 8mo ago
    Uhm... The article lacks quite a few citations.
  - AftHurrahWinch 8mo ago
    Really enjoyed this: > In the centuries after Archimedes invented the Archimedes' screw, developments of propeller design led to the torus marine propeller... it was invented in the early 1890s "the centuries" indeed. :)
- HoldOnAMinute 8mo ago
  I didn't even see a picture of the propeller, if there was one. There was a giant, white, blank space.
  - LoganDark 8mo ago
    That space is blank for me too. This page seems to have one halfway-functional photo for me: https://www.sharrowmarine.com/store/p/sharrow-by-veem-ds9sw https://www.sharrowmarine.com/store/p/sharrow-by-veem-ds9sw This URL may work: https://images.squarespace-cdn.com/content/v1/560055b1e4b017b5db4fb31f/3cb717fa-7ac5-4529-9262-818416e86e4f/9+-+SHARROW+by+VEEM.png https://images.squarespace-cdn.com/content/v1/560055b1e4b017...
    - dylan604 8mo ago
      If that's machined, that's impressive. I've seen some crazy 5-axis CNC examples, and it's usually some bladed turbine fan. Not sure how many axis (axii??) this would require, but it looks cool nonetheless.
      - 8mo ago
brk 8mo ago
For the most part the Sharrow props have not proven to be much of an improvement, particularly for the high price. The tests that have shown "significant" improvements have frequently compared the Sharrow to a sub-optimal prop. Feedback from many actual users is that the gains are moderate over a narrow RPM range.
- closewith 8mo ago
  And much harder to repair.
- jcgrillo 8mo ago
  Do you have any more information/sources to share on this? I have an Eastern 18 powered with a Yamaha 60hp 4 stroke and I've been struggling to dial the prop right. I don't know off the top of my head what the specs of my current prop are but basically I feel like I'm not taking advantage of the engine's torque at less than WOT, so I basically just run it flat out. If I could extract just a little more thrust out of the prop at lower RPMs it feels like the engine would have enough grunt to make the boat plane in the mid-high 4000s instead of 5000-5200rpm where I currently run it. Ideally, given the bsfc/hp curves, I'd like to run the engine at a bit lower RPM, but the way it's currently set up at ~4600rpm it's not fully up on the step. I was (perhaps wishfully) thinking a little more efficient prop design might help. The other thing I was thinking of trying is swapping in a different "high torque" lower unit with a lower gear ratio and running a significantly larger prop.
  - brk 8mo ago
    Sources are primarily boating forums, dockside conversations, etc. In theory your boat in right in the sweet spot of recommended power range at 60HP. I don't know all the background on it, so all kinds of potential problems, but I would wager that "propped wrong" is unlikely to be the core culprit. I'd start by getting it weighed and comparing your loaded weight to manufacturer specs. USCG requires positive buoyancy for hulls under 20'. This is typically achieved with using expanding foam in hull cavities, and that foam can have a tendency to absorb and hold water if the boat develops any failure of the seals around the bilge areas that are foamed. Reports of poor performance are very common for these sub 20' hulls because of waterlogging. If not a waterlogged hull, you might also just have too much stuff on-board. To a lesser degree, a bimini can also have an adverse affect on speed/planing, if it's acting like a parachute. Not sure if you have a bimini, but if so it's worth trying a run with it up vs. down. I'd also look at how your outboard is mounted. It's not clear if it the outboard from the factory, or if the boat has been repowered. Outboards being too high, too low, etc. are pretty common issues that can also majorly impact performance. That's a few thoughts that comes to mind off-hand.
HPsquared 8mo ago
That's pretty cool, but I wonder if they can get stuff tangled in there.

martinclayton 8mo ago

See also https://news.ycombinator.com/item?id=26339421 https://news.ycombinator.com/item?id=26339421

xpe 8mo ago

I recommend this video with animations : https://www.youtube.com/watch?v=QrBF9BWYAZY https://www.youtube.com/watch?v=QrBF9BWYAZY

xpe 8mo ago

From a resilience POV, my guess would be that failure of any one blade would botch the system overall. Maybe that is why many diagrams show them installed in pairs. (I would guess each operates in a different direction for angular momentum reasons.) I have no idea about overall reliability.

brk 8mo ago
For marine applications dual drives are common as it enables better rotational control for maneuvering. The redundancy aspect is also a factor, but moreso for applications where you are going to be far from shore. For tugboat and ferry type applications, where these drives are most common, that is less of a concern.
w4der 8mo ago
They are installed in pairs and work together with bow thrusters to allow for dynamic positioning, the RV Falkor (too) has them for this reason.
somat 8mo ago
I think you are right, One only provides directional thrust, a pair would be needed for rotational thrust. Most traditional tugs have a pair of screws for just this reason. Not so much to turn but by applying differential thrust they can pull sideways. A vector drive like this will vastly increase the envelope of possible pull conditions.

oliwary 8mo ago

Cool, similar to helicopters which can also control direction indepentendent of thrust, which leads to RC helicopters being able to pull of crazy, physics-defying moves like here: https://www.youtube.com/watch?v=QSiwyoQldfo https://www.youtube.com/watch?v=QSiwyoQldfo

_aavaa_ 8mo ago
Thanks! I’ll keep this on hand for next time I hear that a UFO proof video comes out saying that an object can’t move the way it does on screen.
- Someone 8mo ago
  Wing area (roughly) scales by n² and mass by n³, so size matters for this kind of thing. See https://en.wikipedia.org/wiki/On_Being_the_Right_Size https://en.wikipedia.org/wiki/On_Being_the_Right_Size (PDF at https://www.phys.ufl.edu/courses/phy3221/spring10/HaldaneRightSize.pdf https://www.phys.ufl.edu/courses/phy3221/spring10/HaldaneRig...)
ted_dunning 8mo ago
That is bizarre and amazing. I have never seen any kind of aircraft that resembled a dragonfly as much as that. The maneuvers are so extreme and come so fast that I would not have been able to say for certain that this wasn't just a very nasty crash in progress. But they were, in fact, completely controlled and intentional. Incredible.
dylan604 8mo ago
That's the worst lawnmower I've ever seen. It didn't even cut the grass as much as it just bothered the blades of grass. 0 out of 5 stars. What's that? It's not a mower. Oh, well then, that thing is cool as hell, but not as cool as the pilot that looks like he's just casually standing there.
- torkal 8mo ago
  This made me chuckle:)

manyturtles 8mo ago

These were used on three car ferries in Scotland, mostly between Gourock and Dunoon but the same vessels were sometimes used on other routes. The Saturn, Juno and Jupiter which were quite fast and incredibly maneuverable: "...service speed was around 15 knots (although she could also achieve 13 knots astern and 3 knots sideways" with just those drives. No separate screws, bow or stern thrusters. Same drive was used on a few smaller local ferries, too. If I remember right what they didn't do was go exactly straight. You could see a (very modest) s-shape in the wake over distance. ref: https://www.shipsofcalmac.co.uk/fleet-features/the-streakers https://www.shipsofcalmac.co.uk/fleet-features/the-streakers

silveira 8mo ago

The same article in german has some nice animations: https://de.wikipedia.org/wiki/Voith-Schneider-Antrieb https://de.wikipedia.org/wiki/Voith-Schneider-Antrieb

crest 8mo ago

They're really useful for tugs and other specialty applications that need the ability to have differential thrust in arbitary directions with lots of thrust at low speed, but loose to Azipods on faster and larger ships.

Keekgette 8mo ago

[flagged]