
Rotor sail helps Finnish ferry Viking Grace reduce fuel consumption - velmu
https://metropolitan.fi/entry/rotor-sail-helps-finnish-ferry-viking-grace-reduce-fuel-consumption
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dzdt
Cargo ships are currently burning the dirtiest fuels available -- so-called
bunker fuel. Regulation is finally forcing a degree of cleanup by 2020,
limiting sulfer emmissions.

Cargo shipping is ruthlessly cost-competitive, and fuel is currently 50-60% of
costs. [1] With the new regulations that percent will increase.

Still it is telling the rotor sail in the example is on a passenger ship
(where it has more PR value) not a cargo ship. That says to me the cost
savings are really not there yet. Probably even stronger clean shipping rules
are required before this kind of thing will be cost effective.

[1] [https://www.morethanshipping.com/fuel-costs-ocean-
shipping/](https://www.morethanshipping.com/fuel-costs-ocean-shipping/)

~~~
agumonkey
Would it stop absurd transportation of goods like exotic fruits all year long
?

If people stopped buying things from far away that aren't really really
necessary, maybe that will also reduce fuel use.

~~~
nitrogen
Buying things from far away is _the point of living in a modern, global
economy_. You don't get people on your side by telling them they want the
wrong things. The way forward is to give people what they want in a
sustainable way.

If someone's feet hurt, you don't tell them to lie down for the rest of their
lives. You tell them to get better shoes.

Global trade reduces global warfare, too.

~~~
agumonkey
I'm happy about warfare channeling through economic relations but the rest is
bullshit IMO. I believe more in locality rather than having constant supply of
things from all over the world. And that it's "THE" point of a modern economy
couldn't be more pointless to me.

~~~
ithkuil
I'm genuinely curious about what is the right size of "local"

~~~
agumonkey
same timezone, same latitude band ?

~~~
emj
That means a car economy, the question of what is local is a good one, there
is a reason the world population is spread out the way it is.

~~~
agumonkey
\- grow more vegetables and fruits nearby (lots of unused space)

eat them

\- gather local material as much as possible

use them with creativity (see the wood based buildings for instance)

I don't accept the "world status" anymore

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trothamel
[https://en.wikipedia.org/wiki/Cargo_ship#Size_categories](https://en.wikipedia.org/wiki/Cargo_ship#Size_categories)

The air draft of a ship is a limited resource, as if a ship is too high above
the water, it won't be able to pass under bridges and other port
infrastructure. It strikes me that adding 24 meters to this might not be
something cargo ships are willing to do.

See, for example, [https://www.joc.com/port-news/us-ports/port-new-york-and-
new...](https://www.joc.com/port-news/us-ports/port-new-york-and-new-
jersey/bayonne-height-restriction-removal-aids-ny-nj-port-
navigation_20170425.html) , where $1.3B is being spent to raise a bridge 64
feet to accompdate larger ships. That's 19 meters, which is in the ballpark of
24.

~~~
chuckledog
Some of the rotors are retractable.

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tuukkah
Please note this ship was quite unique to begin with: it's a 5-year-old
12-deck cruiseferry that burns gas instead of oil.
[https://en.wikipedia.org/wiki/MS_Viking_Grace](https://en.wikipedia.org/wiki/MS_Viking_Grace)

Here's an image of the ship with the new rotor sail on top:
[http://www.maritimeherald.com/2017/cruise-ferry-viking-
grace...](http://www.maritimeherald.com/2017/cruise-ferry-viking-grace-
install-turbosail-for-hybrid-usage-of-wind-power/)

~~~
lsc
the physics involved must be really interesting. Visually, the "sail" looks
incredibly tiny compared to the size of the ship and the size of sails on
sailing ships of earlier ages

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bufferoverflow
There are also large kite systems for ships, taking advantage of stronger
winds at higher altitudes. Savings of up to 20% fuel.

[https://en.wikipedia.org/wiki/SkySails](https://en.wikipedia.org/wiki/SkySails)

[http://www.dailymail.co.uk/news/article-5186905/Cargo-
ships-...](http://www.dailymail.co.uk/news/article-5186905/Cargo-ships-KITES-
help-slash-fuel-bills.html)

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doitLP
Simple video that shows how the Magnus force works:
[https://m.youtube.com/watch?v=O6JdMSpiIqU](https://m.youtube.com/watch?v=O6JdMSpiIqU)

~~~
tensafefrogs
Thanks! Seeing this reminded me of this basketball being dropped off the edge
of a dam:

[https://m.youtube.com/watch?v=PM9vnEWmA1c](https://m.youtube.com/watch?v=PM9vnEWmA1c)

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chuckledog
Wikipedia link:
[https://en.m.wikipedia.org/wiki/Rotor_ship](https://en.m.wikipedia.org/wiki/Rotor_ship)
“Flettner constructed an experimental rotor vessel; October 1924”... Not
practical. Renewed interest this century, improved design. New ships: Viking
Line to reduce fuel consumption up to 15%. Maersk to start testing 2018.
Norsepower to cut 7-10% of fuel cost in big tankers.

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paulsutter
Why one? Why not 5 or 10? (since the savings quoted are between 10% to 20%)

I realize this must be a test, but I’m surprised they don’t discuss plans for
multiple. Are the projected savings actual or “theoretical”?

~~~
rileyphone
I think some ships have two, but the reason you can't stuff a bunch in there
is the same reason planes usually have only one wing.

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ouid
most planes have 5 wings under any reasonable accounting.

~~~
nabla9
Most planes have only two wings. Wings producing lift and keep the plane up.

Two little horizontal 'wings' at the back are horizontal stabilizers. They are
like wings but installed upside down (they produce negative lift and push the
tail down).

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kazinator
Doubt it is purely based on pressure, as the diagram insinuates. Like the lift
effect of an aerofoil, much of it comes from entrainment: the phenomenon that
the device is basically causing the moving air to stick to it and then
"throwing" that air at an altered angle which generates thrust.

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LifeLiverTransp
Stupid question- but there is are huge currents under water- could they be
harvested for additional forward motion?

[https://en.wikipedia.org/wiki/Ocean_current](https://en.wikipedia.org/wiki/Ocean_current)

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tonyedgecombe
I wonder if we would be better off sending stuff by rail, at least for Europe
we are connected by land to China.

~~~
no_wizard
From what I have come to understand sea based goods transportation isn’t
nearly as subject to the political whims of a nation as land based travel.
That’s one of its main advantage sis that even if say nation A has an issue
with nation C nation A can still sell goods to nation B without issues of C
blocking their travel

With land based transport, it is wholly dependent on a nation state to be
cooperative. Thst isn’t to say it wouldn’t be a solvable problem and I think
generally most nations would see the benefits quickly but it only takes say
the Russians having a fallout with the US (I’m the case of ever building that
mythical Alaska to Russia bridge in the Bering sea to interconnect the
continents) for them to cut someone off. Or let’s say a middle eastern
terrorist group decides to blow up trade tracks that lead from China and great
Asia into Europe.

Most of that political strife is safely ignored via sea trade. Honestly I
believe that’s what holds back globally connected rail which I think has a
cheaper long run cost and could more reliably deliver goods in a perfect world

I don’t have sufficient research to back this up at the one time though I
simply just remember reading about this a few years back

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mrfusion
I’m confused. Can they only operate this when the wind I perpendicular to the
direction the ship wants to go?

~~~
kpil
I suppose it works like ordinary sails, but without decent trim - the shape of
the hull and rudder counterbalance the perpendicular force and you steer
slightly crosswind to compensate for drift.

You won't be able to go directly into the wind, as the forward component can't
be too small.

I guess you need to spin it in the right direction unless you want to go
backwards...

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mrfusion
Why would this be better than sails?

~~~
fulafel
You mean compared to traditional sailboat sails? There don't seem to be
products that would add them to traditional cargo ships or ferries. Probably
blocked by the crew skills and effort needed to operate and maintain them, as
well as more invasive structural demands placed on the ship.

The only other recent sail boost attempt is kite based approach:
[https://www.treehugger.com/cars/cargo-ship-with-kites-
first-...](https://www.treehugger.com/cars/cargo-ship-with-kites-first-trans-
atlantic-trip-a-success.html)

A cynic might of course also propose that you can't get public research money
or patents for a product based on traditional sail...

~~~
Someone
_”as well as more invasive structural demands placed on the ship.”_

Why would that be the case for a sail that gives the same fuel reduction? Are
these rotors less impacted by sudden gusts of high wind speed than traditional
sails?

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Sharlin
A rotor sail is just a tube that rotates. Regular sails need complicated
rigging.

~~~
Someone
Why? Without additional arguments on the table, I would think the force
exerted on the wind-catching structure would be equal between sails and these
rotors, for equal efficiency gains.

That load has to go somewhere. Rigging is a way to do so with traditional
materials, but nowadays, a sturdier mast without rigging is possible.

(Rationale: if the ‘mast’ hidden in these rotors can be made strong enough, we
can also create a mast holding a traditional sail taking the same load)

~~~
newnewpdro
Have you _ever_ been sailing?

~~~
Someone
Does that matter? It’s all physics. If you think my logic is incorrect, point
out where.

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newnewpdro
Rotor sails are relatively insensitive to foul weather and wind direction.

If you had any experience with sailing, especialy on the high seas in a
variety of conditions, you'd have a much better understanding of the problems.

If you have the means to go out on the sea in a sailboat, I highly recommend
it. Especially for someone with a STEM background, it's actually a quite
interesting activity.

------
mrfusion
I think the big argument against more efficient cargo ships is that they have
long lifetimes and new ones aren’t built that fast.

I think we should built giant cargo tugs with wind and solar power. They can
just hook up to a cargo ship in the high seas and tow it. That way we can keep
the existing ships.

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jessaustin
_high seas and tow it_

I think this phrase would frighten any professional sailor. Tugboats don't
really operate very far from shore, for good reason. You don't want to be in a
storm and see the giant load to which you are strapped passing you and
starting to roll.

~~~
jononor
If the thing that is towed is a conventional ship, it can use its own power in
such conditions?

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ehnto
You wouldn't want to be in a conventional tug at all in open ocean conditions,
regardless of the tow or no tow at all.

You would need a new kind of tug, more resilient to waves and storms, with
crew quarters, room for provisions and all of the life saving gear a normal
open ocean ship has. You may as well build a new cargo ship.

~~~
nherment
Not to say that the argument to have tugs pull barges offshore is sound, but
high sea tugs exist:
[https://en.wikipedia.org/wiki/Abeille_Bourbon](https://en.wikipedia.org/wiki/Abeille_Bourbon)

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mrfusion
It seems like there’s not enough surface area to capture much wind energy.

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justinator
Wouldn't just not having something as superfluous as luxury cruise ship lines
reduce fuel consumption even more?

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georgeecollins
How I know this article wasn't written by an AI " In addition to reduced
strain on the enviornment, the rotary sail has a strong financial incentive
for. "

