Sine wave propulsion

Sine wave propulsion is very differing from sculling. After sculling people used paddle wheels. Oars and paddle wheels use the same principle of operation. Screw propeller forced oars and paddle wheels out of a modern sea and river transport. I think the sine wave propulsion will be next because it is the most efficient propelling means (see my thread 8191 “Fishes and dolphins are powerful propellers”).

 

It works II

Vlad,
I'm familiar with your work and have been following the thread you started (BTW, I rated it 5 stars... )
The subject is both interesting and promising.
Paddlewheels, rowing oars and paddles have in common the fact the blade enters the water, pushes it backwards, is lifted above the surface and then brought forward to re-enter the next time.
Yuloh sculling is different since the blade is never lifted above the surface: It stays under water all the time and is moved in a way that's similar to the movemnet of a fish tail (horizontal, left-right).
See here:
http://www.simplicityboats.com/ScullYulohaboat.htm
The fact people have been using this principle for millenia proves that it works and should be further developed to be used in faster and bigger watercrafts as well as in small, human powered boats.

It seems a horizontal, left to right movement may be easier to implement in surface crafts than an up and down movement.
Here are two small, human powered boats making use of a concept that's reminding of sculling:
http://ondulo.com/
and
http://tailboats.com/

Yoav

 

Leonardo Da Vinci was the imagineer who thought up those things.
http://www.lairweb.org.nz/leonardo/
He actually did describe many devices that would be realized after his time. He is one of the most remembered creative personalities in the history of the world. He is a role model for me for over 50 years.

It is true that he did not overcome all of the practical impediments to seeing his ideas realized, but that in no way diminishes the genius of his work. All new developments arise as a series of steps taken by many people over the course of centuries. Sikorsky, the developer of the moderrn helicopter is said to have been influenced to do so by the work of da Vinci centuries earlier.

Just because something is not practical at a given point in time does not mean that the discussion should end because of the certainty of critics and skeptics. Why, among many millions of inventors and creative persons is da Vinci so outstanding? It is partly because he had a series of older mentors, who from the time of his youth encouraged and supported his "imagineering". I have been to da Vinci's birthplace (Vinci, Italy) and the museum there dedicated to his life. Without encouragement from others he never could have produced such a dramatically creative body of work. That is why I believe that in a collaborative creative design process (like boatdesign.net) it is better to be encouraging than disparaging. And masrapido, I had no intention of doing that to you, so if I said something to make you feel that way, I apologise.

Aloha from Hawaii,

Jonathan

 

Yes, of course it was Da Vinci. No idea why I wrote Gallileo.

 

I knew about http://ondulo.com/ and http://tailboats.com/ before and used to scull myself as stated in http://www.simplicityboats.com/ScullYulohaboat.htm but never knew that was ‘sculling’. You can see the sculler propels his boat by simply reversing his stroke. In fact the sculling oar works as a screw propeller blade. As long as the sculler makes oscillatory (not rotary) motion, he must turn the oar blade on a certain angle in each stroke (swinging propeller). It is easy to see the screw propeller blades have optimum position to create a directional water jet. Sculling cannot be efficient because the oar blade push water more up and each side then back. As to tail boats I see in them an approximate attempt to imitate fish locomotion.
There is no difference in efficiency of a horizontal and left to right movement of the sine wave propulsion device. We can use it this way, that way and every way.

 

Is a surface propellor a rotating sculling device?

 

Could you make clear your question please?

 

When I was 16 years old, I had one year re-education in a boatyard. What was my working? my working was to make the oar for the boat! this is the most technique job in the boatyard, there were only one old master can do this job. every day I use a axe to cut a big wood to oar, it is reary a hard work. the oar use high quality wood, the wood had put in the room for many years, if the oar is distorted or miss designed, then you will got trouble that will very difficult to scull. the oar is much big than in the picture, it takes 3 month make one oar.

I think I am the only one can make this kind oar in this world.

 

If string theory is correct...

then any form of wave based propagation is likely to turn out to be the most efficient because it is likely to have a higher energy conversion rate.

Waveless; please get yourself an apprentice or better yet contact the Viking Ship Museeum in Rolkilde Denmark http://www.vikingeskibsmuseet.dk/ I know they would love to have you teach someone your tecnique they have several boatbuilders employed there who do everything the old way by ax. You would feel like you were 16 again among those guys.

Maybe some of you math wizards can calculate the right amount of flex for sculling oar?

I suspect that the efficience will go up when the harmonic of the oar matches the stroke, it does in all other low loss resonance circuits. This is undoubtedly why Waveless was tought to buil the oars in one piece with continuous grain.

The fast fish are probably not using their muscles continuously - rather they use bursts of power that is released in a "wave" by their body. It would be interesting if someone who knows fish anatomy can contribute - I surely have not seen a lot of large blodvessels in the ones I have eaten.

 

How do fish swim

Asathor,

Here's an article on the biomechanics of swimming fish: http://www.ece.eps.hw.ac.uk/Research/oceans/projects/flaps/swim.htm

Indeed, "harmony" seems to have a lot to do with this type of propulsion.
In terms of naval design maybe we should get used to think of the hull and the "propeller" (tail, fin, wing, oar - whatever) as two parts of the same thing rather than two completely different things?

Yoav

 

lateral cancellation in sine wave propulsion

Clearly different approaches to propagate the wave have differing advantages with respect to speed and maneuverability.

From: http://www.ece.eps.hw.ac.uk/Research/oceans/projects/flaps/bcfmodes.htm
Anguilliform mode

Anguilliform is a purely undulatory mode of swimming, in which most or all of the body participates. The side-to-side amplitude of the wave is relatively large along the whole body, and it increases toward the tail.The body is long and thin, while the caudal fin is typically small and rounded, often missing altogether. The inclusion of at least one wavelength of the propulsive wave along the body, means that lateral forces are adequately cancelled out, minimising any tendencies for the body to yaw. Typical examples of this common locomotion mode are the eel and the lamprey.

[This cancellation of lateral movement is what I was trying to explain in another thread initiated by Vlad]


Subcarangiform mode

Body movements in subcarangiform swimmers (e.g. trout) are vey similar to anguilliform mode, the main difference being that the side-to-side amplitude of the undulations is small anteriorly, and expands significantly only in the posterior half or one-third of the body.


Carangiform mode

For carangiform swimming the body undulations are further confined to the last third of the body length, and thrust is provided by a rather stiff caudal fin. Since less energy is lost in lateral water shedding and vortex formation, efficiency is improved and carangiform swimmers are faster than anguilliform or subcarangiform ones. However, their turning and accelerating abilities are compromised, due to the relative rigidity of their bodies. Furthermore, there is an increased tendency for the body to recoil, because the lateral forces are concentrated at the posterior. Lighthill identified two main morphological adaptations associated with the minimisation of the recoil forces: (i) a reduced depth of the fish body at the point where the caudal fin attaches to the trunk (the peduncle) and (ii) the concentration of the body depth and mass towards the anterior part of the fish.


Thunniform mode

Thunniform mode is by far the most efficient locomotion mode evolved in the aquatic environment, where thrust is generated with a lift-based method, allowing high cruising speeds to be maintained for long periods. Significant lateral movements occur only at the caudal fin (producing more than 90% of the thrust) and at the area near the narrow peduncle. The body is very well streamlined, while the caudal fin is stiff and high, with a crescent-moon shape often referred to as lunate. Despite the power of the caudal thrusts, the body shape and mass distribution ensure that the recoil forces are effectively minimised and very little sideslipping is induced. Although the design of thunniform swimmers is optimised for high-speed swimming in calm waters, it is particularly inefficient for other actions such as slow swimming, turning manoeuvres and rapid acceleration from stationary, as well as for turbulent water.



The gradation of the undulatory BCF swimming from anguilliform to thunniform modes (Source: Lindsey 1978).

 

The only person qualified to talk about these speculative propulsions is the one that actually tested one.

http://www.dahlberg-sa.com/kd/Tail.htm

The rest of the bunch is just sauerkraut philosophy. And I apologise to all who recognise themself as such.

I wander what would Kjell have to say on efficiency and speed achievable.

 

On the above: note the absence of waves, remark why is that, and that Kjell is using horizontal movement.

Also, Kjell has substantially solved problem with vibrations caused by tail-propeller movements. He paired them up, and I bet they are moving sinchronously in opposite direction to each other. One to the left, the other to the right. To reduce those vibrations that would make passengers sick.

His work is showing that there might be a way to use the PRINCIPLE ( of fish movement) to propell the boat/ship. Such propulsion may be adequate for work boats where advantages would be significant. As for the fast boats, I'd still stick with a rotary propeller. It turns full 360 degrees.

But I personally prefer sails for my boat.

 

State of the art

Masrapido,

1. Sine wave propulsion is not speculative since is has been successfully used in human powered boats for millenia (E.G. Chinese yoluh-sculling).
2. Kjell's research and findings are remarkable and they clearly suggest that this field is worth further investigation. Being a methodical researcher Kjell is likely to be the first to point to the multitude of related subjects that his research could not encompass, probably due to lack of funding. I'm sure we can all agree that it is regrettable, and he should have continued investigating. Even the limited set of variables he was able to check clearly merits a much broader investigation.
3. Other research done in this field adds to our understanding of the way sine wave propulsion works and clearly points to its potential.
4. There is no reason for us to assume that sine wave propulsion, when properly applied could not be used for fast boats, big ships etc. After all, in the natural world it is used by creatures ranging from microscopic size to 200 ton whales, and often in speeds that surpass our understanding.
5. As a boat designer and manufacturer I am grateful to people like Vlad and Jon who start such high-level discussions and "speculate" on technological subjects whose state of the art has not yet attained a commercial level. I find free-flowing discussions such as this to be both informative and intellectually stimulating, and therefore very useful.
However I can also understand why a consumer looking for a propeller for his boat may think of it as far fetched.

Yoav

 

everyone seems to be forgetting that his idea was to

Hi Yoav,

Very interesting comments. I would like to point out to you that Vladzenin himself said that sculling is very different to sine wave. Also, it seems to be escaping to many that Vladzenin started his sine vawe debate by applying it to swimming. Debate took off, on a (tangential) vawe of enthusiasm, and turned into boat/ship debate. I would also like to point out to you that Jon believes this to be, dare I say, highly speculative subject/forum.

So, as we can see there's a multitude of opinions and even when some people agree on something, it may be for a whole set of different reasons.

In the meantime, I see nothing but theory in these, speculative or not, discussions. And on their face value, I cannot agree with what peole are saying. It is to far-fetched for a humble boat design forum. It does not contain any useful verifiable information, like tests, experiments, mathematical equations from which claims of efficiency were derived etc.

Many are obviously not familiar with ancient sculling, or they are missing the point here. Sculling is used on rivers for travelling DOWN the current. it is basically used for MAINTAINING the direction, not for propulsion. Venetian gondoliers actually use plain battons to push the boats because the channels are shallow. Yes there were some, with oars at the back, so what does that prove? They were used on boats for couples. Romantic, slow rides. Not dangerous US-style police chases around the channels of Venezia.

Try to scull up the stream and you will see that "classical" rowing is more efficient. As for the boats, where is the claim of being more efficient coming from? What tests, experiments trials? Against what comparable other propulsion? Oars? Show me the data, not some enthusiastic "This is revolutionary" sales pitch. Fish movement is complex, like bird's flying movement. And, as I said before, airplanes aren't flapping around the airports. Will be for a reason, wouldn't you agree?

Now, I like the work Kjell has done and there I see results that suggest possible use. He has tried it and is not making any bombastic claims. That will be for a reason too, wouldn't we all agree?

Why I say I'd stick with a propeller? Because propeller turns 360 degrees and is in uninterrupted movement, constantly providing the power. Kjell's experiments CLEARLY show that every flap has two zero moment positions where there's no work done. In a system of two flaps, there are four moments like that. Waste of time and energy because to move a flap into the opposite direction you must push it from zero. That requires a lot of energy. Not to mention braking energy loss from reaching the top of sinusoidal curve, if you know what I mean. Vlad, Jon?

As an engineer you should agree with these axioms. Hence, sine wave flapping is NOT as efficient as a propeller. By the nature of it's movement. One should be blind not to see it.

THAT is what I am saying. Of course it may help propell a boat reasonably fast, but at what cost? Instead of crying foul, sofa engineers and inventors should have a look at this and propose solution, if there's one (don't think so). Not clog the forum with links to experiments that have clearly failed to yield results, or debating fish in support of their unsupportable claims.

My remarks were not derogatory about the idea. My remarks, paradoxally, were constructive. Pointing at already identified shortfalls that budding inventors should have been informed about before going public with rather old ideas. I actually wanted to help.

But my remarks were not proven wrond. Simply refused with lots of noise. Noise instead of argument, we know what does that mean.

Since you are boat designer, would you share your technical expertise in analysing the merits AND shortfalls of this idea with us? That way we would have something technical, more scientific, to discuss.

Regards from ras rapido (faster in espanol)

And metrics please...Whole world is using metrics, those few imperialist left around, we'll get you...