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[cos918]

found this sim on another froum bit of fun

john

http://www.voithturbo.com/545950.htm

[Tug-Kenny RIP]

It is good, isn't it.  Explains in pictures how they work.

Thanks for that

ken

[Peterm]

That is a brilliant explanatory method.  pete M

[catengineman]

If you use the joystick method then that is the same as in a transmitter to a tug with VS fitted

[douga]

worked on voith scnider prop system in the 1970,s was o tug  Waitangi at northland horbour in NZ
must put this as a project for the future very interesting :)

[Roger in France]

Great, thanks.

Hope Umi sees this, she explained to me how it all works some time ago.

Roger in France.

[Martin (Admin)]

Just as a matter of interest, how many modellers on here have build or own a model with a Voith Schneider Propeller?

[Umi_Ryuzuki]

I have the fireboat, and have 0ld and new graupner drives for two
more projects using twin voiths... I just haven't figured out what the projects will be... ::) 
Sound of Sleat, Sandown or Osprey class MHC, another tug...

[catengineman]

My tug Venture has twin VS units.

Did LMBC regatta and during the steering comp I did the whole course going astern  (came second)
Then as I have working monitors was a fire boat and put out a tanker fire (had fun wetting the female judge)

R,

[toesupwa]

Just as a matter of interest, how many modellers on here have build or own a model with a Voith Schneider Propeller?

Not 'Built'.. but gearing up for a scale build of Crowley Scout based in San Pedro, LA Harbour, USA... Twin Voith's and an enclosed keel cooled system..

[mike_victoriabc]

Nanuq under construction - running gear appears to do what it is supposed to do. Behind in finishing the wheelhouse, upper deck details.

[craftysod]

we had the vs on hms challenger (so called diving ship more of white elephant) ideal for manouverability crap for speed

[catengineman]

Yes agree with that craftysod great on close quarter handling tugs and ferry's but on a sea going vessel think again
Oh and don't run shallow! the table while strong enough to hold the vessels weight isn't good at being a plough and the blades break the controll gear easy as well as bend 

Dry Dock bill massive

R,

[Hagar]

Been looking at PARAT for a while.
Find the whole idea of this system very confusing, but having played with that link, not so confused, bt stil cant se how it works !!! :'(

[catengineman]

Been looking at PARAT for a while.
Find the whole idea of this system very confusing, but having played with that link, not so confused, bt stil cant se how it works !!! :'(

Have you ever stired water with your hands?

stand in a swimming pool and then stir the water infront of you, when you are doing this then twist your hand through 90 degree at the same point every rotation this gives you the "thrust" at a given point now while still doing the above alter the place where your hand is at 90 degree to your body, this moves the "thrust" to a different point result the action on the vessel (you) differs and therefore the movement is the result ie: turning
If you have a body board sit on it and operate both arms in an oppossing maner. it may be easier to have your right arm rotate in an anticlockwise motion and the left in a clockwise (try it) as your arms pass your bady twist both palms out until your arms are fully forward in the circle then twist back to being inline with each other
result forward motion.
If you can try altering only one to twist at a different point (its hard) the body board will move in a different direction

is this any help on how VS units work.

R,         had to think hard on that one.

[Hagar]

Good explanation. This means that all voith units have to work in pairs then, otherwise the boat will just turn all the time...
Was also a bit fuzzy about the fact that this vessel could reverse with the propeller stil turning the same way, but as your little experiment proved, it all depends on where and when the blads are turned as to which way they push the water.

So there has to be two points af thrust, to counteract the turning moment, I get it now. I think.

[Captain Jack]

Ok, so it would take TWIN voiths for these vessels to crab sideways?

[Umi_Ryuzuki]

When Graupner made the smaller drives, Harbour models sold a twin drive escort tug.
However when the drive was discontinued, and the new version came out twice as
big, the model could only support one drive easily. 

Svataka's single voith drive model...video
http://www.youtube.com/watch?v=yg8WhbqhCns

It would take a bit of practice, but with the right thrust vector crabbing should
be possible using a single drive.

People have been putting two drives in, this older model, but
 it takes a bit of extra shoe horning.

[catengineman]

Regarding twin VS and straight lines the answer to that is no

Ok, so it would take TWIN voiths for these vessels to crab sideways?

you can get a single VS unit to drive a vessel in a perfectly straight line and it will be controlable (had to do that with the venture) it is all down to where the thrust is directed from the blades and position on the skeg

The Graupner drives are great and as I said I had to use just one drive when I had a bit of a mishap regarding the VS units but instead of the control stick in the straight ahead possition it was slightly to the left this drove the boat straight.

R,

[Captain Jack]

After playing with that simulator for an hour, I'm convinced a single VS cannot crab perfectly sideways. With a twin screw vessel, with one engine forward, the other reversed, and the proper counter input of rudders, crabbing is possible. While maneuvering a 1:1 vessel, I find it's even easier to do if the vessel is not equiped with kort nozzles. In some cases "prop walk" can be your friend. In the video, any sideways motion appeared to be caused by inertia only. I would love to get my hands on a twin drive VS system, and may eventually model one. Now I've just got to get my head around the ideas if they should be mounted aft, side by side like standard screws, or inline, for and aft on the keel line. Any thoughts on which would be the most maneuverable of the two?

[catengineman]

Hi Captain Jack

Boy are you opening a can of worms with that question! 

Standard prop vessels are constructed in a slightly different way in that the hull is deeper to those of V S vessels they may have the same draft but it will be the V S table that is the reason on the VS vessel.
A single VS will crab, easier than that of a twin screw.
Where would the best position to fit twin VS units? this depends on what the vessel is and its roll.

A tug under normal conditions will have twin units forward of center and along side each other,
A ferry under normal conditions would have twin units (or 3 or 4) these would be at opposed quarters on the vessel, or in the case of a three unit drive train two alongside each other and one at the other end of the vessel.

Have a look at the Graupner "PARRAT" THIS IS A VERY GOOD MODEL THAT WILL SHOW WHAT i AM TRYING TO SAY.
regarding the most maneuverable of the two?

A V S vessel will out maneuver any standard screw vessel (disregard ASD vessels yet again a different handling vessel)

[Captain Jack]

A well made point! I guess considering all factors, my best bet would probably be to go with Z drives. My next build will be another AHT/OSV, as that it where my heart lies from my youth as a Merchant sailor.  I can see the obvious advantages of the VS system for close quarters handling, but I need to also look at the fact that an OSV spends most of it's time transiting long stretches of open sea, where a reasonable speed is required for long periods. In a fantasy world with money as no object, I could forsee some type of "retractable" VS to be used for station holding while offloading at the rigs, and Z drives for use while underway. Indeed, that would be an expensive proposition, but would make for a very unique vessel as a model. The only drawback would be a hull shaped for the VS, mostl likely would have terrible seakeeping characteristics. It's good to see vessels like the Bourbon Orca designed for crew comfort and safety coming off the ways now days...the damn thing is UGLY though!

[catengineman]

Have you not thought about a retractable ASD in the bow of the vessel?

ASD's are 360 degree opperational and with twin rear units then a further one fwd that would make for a trully controllable vessel

Cheaper than the VS units and there are two sizes out there that I have used 1,Graupner 2, Robbe  (schottles) ASD's to me but whats in a name?

R, (just a thought)

[Captain Jack]

I've heard many people bad mouthing those units as far as reliability. Probably most of it comes from those who have never actually owned them. Your advice is well respected on this end. What are your opinions of them, sir?

[Garabaldy]

http://www.shipsofcalmac.co.uk/h_jupiter.asp

thats an interesting article which describes a calmac ferry which had 2 of these units fitted in line.

the captain of the ship herself said it was a failed design.  Its interesting reading.