
World’s Largest Containership Also Sets Record for Largest Engine Ever - SuperChihuahua
http://gcaptain.com/worlds-largest-containership-also-sets-record-for-largest-engine-ever/
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ChuckMcM
When I toured the USS Carl Vincent (a nuclear air craft carrier) at Alameda I
was surprised at how "small" its engines were relative to large container
ships. It helps that they are electric of course (no big gas expansion
chambers) but I suspect if it weren't for the proliferation concerns cargo
ships of this size could be economically run on nuclear power plants.

~~~
beefman
Indeed, Nimitz-class carriers have far more powerful engines,[1] as do as do
Russian-made icebreakers, which are civilian ships,[2] as did Savannah, an
American civilian ship.[3]

Edit: Carl Vinson, like most nuclear-powered vessels to date, is direct-drive.
The Ohio Replacement Submarine is slated to have electric drive.[4]

1
[http://en.wikipedia.org/wiki/A4W_reactor](http://en.wikipedia.org/wiki/A4W_reactor)

2 [http://en.wikipedia.org/wiki/Nuclear-
powered_icebreaker#Russ...](http://en.wikipedia.org/wiki/Nuclear-
powered_icebreaker#Russian_nuclear_icebreakers)

3
[http://en.wikipedia.org/wiki/NS_Savannah](http://en.wikipedia.org/wiki/NS_Savannah)

4
[https://en.wikipedia.org/wiki/Ohio_Replacement_Submarine#Ele...](https://en.wikipedia.org/wiki/Ohio_Replacement_Submarine#Electric_drive)

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Swizec
Why is it good for ship engines to be so low rev? I imagine part of it is fuel
savings, but with cylinders that big ...

Does it burn more fuel to run a small engine at higher revs, or a big engine
at lower revs?

The only other thing I can imagine being a factor is torque. Do low-rev
engines have higher torque?

~~~
cellularmitosis
(speaking just to size, not RPM:) The square-cube law causes the burning
gasses in a larger cylinder to bleed less heat away into the water jacket
compared to a smaller cylinder. This is the primary reason why the largest
diesel engines in the world are also the most efficient.

Theoretically, the 14-cylinder Wärtsilä-Sulzer RTA96-C could be even more
efficient if it were instead a gigantic single cylinder. There must be some
other engineering or economic limitation which prevents us from manufacturing
25,000 liter cylinders.

edit: example: [http://en.wikipedia.org/wiki/Square-
cube_law#Engineering_exa...](http://en.wikipedia.org/wiki/Square-
cube_law#Engineering_examples) "Watt recognized the problem as being related
to the square-cube law, in that the surface area of the model's cylinder
surface to volume ratio was greater than the much larger commercial engines,
leading to excessive heat loss"

edit2: There is also a square-cube law with aerodynamic losses related to
piston speed (how fast the air gets sucked into the engine: "pumping losses").
The slower you spin the engine, the lower your pumping losses are. However, I
believe this plays a smaller role in affecting efficiency than the heat
losses. (also, this engine is turbocharged, which changes things a bit).

~~~
TylerE
A single cylinder that big would have SERIOUS vibration issues. Imagine
dropping, oh, a 20,000lb weight from a height of 10ft. Every 6 seconds or so.

~~~
cellularmitosis
That can be overcome with balance shafts. [http://what-when-
how.com/automobile/engine-balance-automobil...](http://what-when-
how.com/automobile/engine-balance-automobile/)

~~~
Evolved
Like what Tyler said, balance shafts to counter a single cylinder would be
huge but also they'd add unnecessary complexity that could otherwise be
overcome by adding additional cylinders instead.

Furthermore, in order to obtain the same level of torque in a single-cylinder
that a multi-cylinder engine creates you'd have to account for the power
generated per cylinder.

In the Wartsila RTA96C you have HP up to 109,000 (rounded) and torque up to
5,600,000ft-lbs [1]. These #s are for all cylinders. Assuming it is the
14-cylinder variant generating this power and you want to reduce this down to
a single-cylinder package then you can easily deduce that the displacement
would be around 25,480 liters (mentioned elsewhere in this thread).

Assuming a stroke to liter ratio of 1.374mm/liter (2500mm stroke for each
1,820 liter cylinder) you'd end up with a 35,009mm stroke for a single-
cylinder engine vs. a 14-cylinder engine. Since there are 25.4mm in an inch
that's a 98-inch stroke for 14-cylinders vs. a 1,378-inch stroke for a single-
cylinder or an 8-foot stroke vs. a 114-ft stroke.

Finally, since you'll need a piston many times larger than the current setup
for a single-cylinder vs. a 14-cylinder engine then you can imagine how much
mass you have moving which can do some serious damage if it becomes
unbalanced. Also you'd have an engine that instead of being long and
relatively low is now very short and extremely tall (not something you want in
a ship where capsizing is a very real concern).

[1]
[http://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96...](http://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96-C)

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slashnull
_eighty three rpm_

wow

For some reason I'm fascinated by how _slow_ this thing is, but it seems
obvious, with the size and all.

~~~
bradleyland
At the full-rated (as opposed to down-rated operational) output specification
provided, that translates (for used to US units) to:

93,496 HP @ 84 RPM

5,845,726 lb-ft @ 84 RPM

The most mind boggling number for me is the torque figure. Almost _six
million_ lb-ft of torque. Power is an important figure when determining how
much work you can do, but torque is important when engineering the components
that will go in to your drive line. For example, transmissions typically
specify a maximum torque input, as well as a maximum rotational speed.
Independently, neither can be exceeded, regardless of power input. For
example, the transmission in my car is good for about 450 lb ft and 9,000 RPM.
I'd love to read over some of the engineering specs for the driveline
components attached to this thing.

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grecy
Can anyone comment on why it's 2 stroke?

Just for simplicity? I have to imagine the stuff coming out the exhaust isn't
so great for the environment.

~~~
kteofanidis
A 2 stroke diesel is different from a 2 stroke gasoline engine. It doesn't
have the same environmental issues because there is no oil in the intake. The
only downside is it needs a supercharger to work so it's not practical in
small engines. Most(all?) large diesels like in trains and ships are 2 stroke
because of the better power/weight ratio.

~~~
grecy
Thanks, I didn't know that.

If there is no oil in the intake, how is it lubricated? Does it have an oil
pump and system like a 4-stroke? (with a sump for the bottom end, etc.)

~~~
Evolved
2-stroke gasoline engines such as dirtbike engines are run with oil in the gas
(thus oil in the intake) for economic and spatial reasons (removing or
shrinking lots of parts like oil pumps, oil pans and ports.

It doesn't really lubricate like a 4-stroke where oil is pumped up and then
scraped back down into the pan. It is still pumped up but it is stored in
devices inside the cylinder liner where it is only dispersed as necessary.
Each cylinder instead has oil squirters (receptacles) in the cylinder liners
and essentially when the pressure under the piston is low enough that the
system has determined there is insufficient oil, spring pressure from the oil
squirters forces out enough oil until the pressure in the cylinder (under the
piston) is enough to overcome the spring pressure and thus the oil squirters
stay closed [1].

[1]
[http://www.wartsila.com/file/Wartsila/1278511883776a12671067...](http://www.wartsila.com/file/Wartsila/1278511883776a1267106724867-Wartsila-
SP-A-Id-2s-Engines-d.pdf)

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justin66
Compares one ship to another, first engine is described in terms of kilowatts
and the next in horsepower. Talks about cargo capacity in terms of TEUs
(shipping containers, I guess) rather than gross tonnage, which is the way
we've always talked about ships forever.

I know nothing about ships but I suspect this is the shipping equivalent of
Information Week.

~~~
TylerE
TEU = 20ft Equivilant Unit. The traditional 40ft semi-trailer style container
is actually 2 TEU.

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jtchang
How do you even start an engine that big?!

~~~
bri3d
[http://en.wikipedia.org/wiki/Air-
start_system](http://en.wikipedia.org/wiki/Air-start_system)

Basically pump a huge amount of compressed air into the cylinders at the top
of their stroke, and then start combustion once the engine is moving.

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chriswarbo
> The two-stroke engine is rated at 69,720 kW @ 84 rpm, although has been de-
> rated to 56,800 kW, and stands a whopping 17.2 meters tall (that’s over 56
> feet!).

Is it really the "largest engine ever"? The Saturn V was 110 meters tall; even
discounting the payload that's pretty damned big.

~~~
onion2k
Surely most of the 110m of the Saturn V was fuel tanks? Perhaps they don't
count towards the size of the engine. If they did, then I imagine include the
fuel for this ship would make it pretty big.

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D_Alex
This one may be larger, though it depends on what one means by "largest". It
is certainly more powerful.

[http://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96...](http://en.wikipedia.org/wiki/W%C3%A4rtsil%C3%A4-Sulzer_RTA96-C)

~~~
mhandley
I agree - the Wärtsilä-Sulzer is both more powerful and longer (but not
taller). This steam engine at Kempton from the 1920s is taller:
[http://www.kemptonsteam.org/history/the-
engines/](http://www.kemptonsteam.org/history/the-engines/)

Still, whichever is largest, all these engines are very impressive.

------
Someone
Largest? I cannot find how large it is, but it has stiff competition from a
steam engine built in 1850:
[http://en.m.wikipedia.org/wiki/Museum_De_Cruquius](http://en.m.wikipedia.org/wiki/Museum_De_Cruquius)

~~~
Animats
There were lots of physically huge reciprocating steam engines in power houses
and pumping stations just before turbines came in. The power ratings were low
by modern standards.

~~~
Someone
I know, but the original article measures the size of the engine in meters,
not Watts. So, the question is whether this thing is larger or not, not
whether it is more powerful.

The cylinder in this steam engine has a 3.5 meter diameter (from the website
of the museum at [http://www.museumdecruquius.nl/historie-cruquius/de-
stoommac...](http://www.museumdecruquius.nl/historie-cruquius/de-
stoommachine/\);) from the photo of the machine room at
[https://www.flickr.com/photos/33129810@N07/4971573233](https://www.flickr.com/photos/33129810@N07/4971573233)
I guess it is at least 10 meters high, and that doesn't include the boiler
room. So, I would guess this is a fairly close race.

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wycx
How is the block on one of these engines fabricated? I would imagine it is not
a one piece casting, so are a few smaller castings bolted together? Are they
made of stacks of plate? Do they have to build a gantry mill over it for
machining?

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mrfusion
Why wouldn't a gas turbine be more efficient?

~~~
nradov
Gas turbines are more efficient in terms of size and weight for a given power
level but burn more fuel. Merchant ships mostly care about fuel efficiency.

~~~
mrfusion
So why do power plants use gas turbines?

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nostrademons
Do they? I thought most fossil-fueled power plants use coal, which they burn
to power a steam turbine. Natural gas plants often use gas turbines, but this
is very different from the gas turbine used by a ship: the latter burns
kerosene, not natural gas. (Natural gas is uneconomical to power a moving
vessel; because it's a gas, you need space to store it, and that space can be
orders of magnitude bigger than an equivalent energy-density of diesel fuel or
kerosene.) Diesel engines or oil-powered gas turbines are very rare for power
plants, outside of backup generators for hospitals etc.

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synack
Yes, but can it run Docker?

~~~
Demiurge
Well, if it does go...

