The Assassin (Sha ren zhe Tang Zhan)

Today, on "Impossible engineering,"

The Harmony of the seas,

the largest cruise ship in the world.

The oasis class of ships is in a class of its own.

Nothing comes even close, in terms of size.

Topping every ship that came before it.

Orit took revolutionary engineering...

To make the impossible possible.

captions paid for by Discovery communications

Royal Caribbean's oasis class cruise ships:

maritime einngeering at an unprecedented alsce.

Since 2009, they've held the title as the largest class

of passenger ships on the planet.

And, today, a third oasis-class vessel

is under construction:

The biggest one, yet.

Longer, wider, and heavier than any other that's come before it.

A lot of technology, engineering, and design

that has been put into this ship class is quite extraordinary.

It's simply mindboggling.

Nothing like the oasis class of ships has been built before.

This is in a class of its own.

The complexity of it is really, really staggering.

Sitting next to her

makes me feel like standing next to the skyscraper.

When it's finished,

the Harmony of the seas will be almost 8 times longer

than the statue of Liberty is high

and 2 times heavier

than the world's largest aircraft carrier.

Building a ship this big would be impossible

without some guidance from the engineers of the past.

Boats have fascinated humans whee!

For thousands of years.

Thank you.

The ancient Egyptians built vessels from reeds.

They were perfect for cruising the nile.

Oh, hello.

But their absorbent nature meant they didn't last.

Wood!

For centuries,

wood was the boatbuilding material of choice.

Warfare led to the use of metals, like iron.

Aah! Aah!

But iron is brittle and prone to rust.

Oh, man.

A new material was on the horizon.

Steel.

And it would go on to revolutionize the world.

In the chamber behind me,

there's about 150 tons of liquid molten steel.

The temperature is phenomenal.

It's about 1,650° celsius.

Steel is made by mixing iron

with various metals and elements.

Oh, my god!

The crucial starting point of the steelmaking process

is to remove the carbon and the other impurities.

And then, it's being poured into the ladle

and it'll go to the next stage,

which is to take it to the converter.

The steel is modified by adding extra alloys

and blowing in oxygen.

What's going on here is the very basics of steelmaking

and this wouldn't have been possible today

without the pioneering work of one engineer that's known

throughout the world by all material scientists.

For centuries, steelmaking was

an incredibly difficult and lengthy process.

That was, until the 1800s,

when inventor Henry Bessemer came up with a solution.

Traditionally, the wrought iron

was layered with charcoal and heated over days

and the charcoal would diffuse into the iron

and that would produce the steel qualities.

Very complex and difficult to achieve

and, therefore, very expensive, historically.

Bessemer developed a way to mass produce steel.

The Bessemer converter.

It's a huge, vast, cylindrical chamber, about 6 meters high

and it would've held 25 tons of steel.

The converter's capacity is impressive,

but its real ingenuity is in how fast it creates steel.

Bessemer discovered that pumping air into iron

accelerates combustion,

increasing carbon reduction and burning off impurities,

resulting in quality steel in a fraction of the time.

To show oxygen injection

really increases the combustion process,

I've got a simple demonstration here.

I've got a tray of charcoal.

With my thermal camera,

I can see the temperature of these coals at the moment

is around about 450° c,

so, now, what I'm gonna do is start to blow pure oxygen

onto these coals and see the effect.

Wow. Look at that.

The impact is amazingly impressive.

Ah!

So, if I now look at the temperature,

it's gone up to 1,000° c, a hugely dramatic increase

in the temperature of these coals.

So Bessemer had found a really amazing process

to reduce the carbon in steel.

Mass production of steel took off.

Its elasticity and strength made it a hot commodity

for railroad- and shipbuilders.

And, although processes have become

more sophisticated and complex,

it was thanks to that engineering genius

of sir Henry Bessemer and his revolutionary machine

that over 1.5 billion tons of steel

are now produced annually right across the globe.

The Harmony of the seas

needs a staggering amount of steel.

When finished, the ship will be longer than

5 football fields back-to-back and weigh over 227,000 tons.

Ssive steel sheets are delivered

to the assembly plant by train.

Automated systems cut the sheets

into thousands of individual components.

The steel panels, girders, and smaller components

are welded into modular sections called blocks.

Individual sections are joined together,

forming what are called grand blocks.

There are 90 grand blocks on the Harmony of the seas.

A custom-built gantry crane

lifts each grand block into the drydock.

The 90 blocks come together

ftoorm the world's largest passenger ship.

But how do

such gargantuan structures move across the open ocean?

Designing an engine for the Harmony of the seas

will be impossible, without some help

from the great engineers of the past.

The biggest cruise ship on the planet

is almost complete.

The Harmony of the seas

will be Royal Caribbean's third oasis-class ship.

It eclipses every ship that came before it.

Sitting as tall as tower bridge,

it's as long as five jumbo jets

and as wide as a soccer field.

When I really look at her, I'm amazed, always,

always, every single time, by the size of the ship.

It's big, but it's beautiful.

It's awesome.

You can definitely call this ship a small city.

It can house almost 9,000 passengers and crew on board.

It's a fully self-sufficient island, if you will.

The Harmony of the seas

is a miniature city, complete with theaters,

restaurants, bars, and other attractions.

How does such a gargantuan structure move

across the open ocean?

The engines are the heart of the ship

and the electrical network is the veins

to provide the power forward to the ship.

Without the engine, a ship is not alive.

Building an engine powerful enough

for this megaship would be impossible,

without help from one of history's great innovators.

The industrial revolution gave birth

to the steampowered engine.

It increased productivity, but enormous boilers were needed.

Oh! Help, please.

To get rid of boilers, engineers broke the mold,

burning fuel within a new engine.

Whoo-hoo!

Compressing gasoline and air and igniting it

with a spark plug to drive a piston,

the internal combustion engine was an industrial gamechanger.

But as the 19th century drew to a close,

an even greater innovation was just around the corner.

Mechanical engineer Henrik Birkegaard

has come to Copenhagen, in Denmark.

A city which owes a debt of gratitude

to an engineering marvel...

Which was inspired

by a truly remarkable innovator: Rudolf Diesel.

This is the HC Oersted power station in Copenhagen.

And, inside, you'll find a giant version

of Mr. Diesel's early engine concept,

which changed the face of the industry globally.

When it first powered up in 1933,

the diesel-powered HC Oersted

was the largest engine of its kind.

It's 40 feet tall and weighs 1,400 tons.

Back in the day, it could produce

a mindblowing 15 megawatts of power.

It's absolutely huge.

Standing next to this 3-, 4-story-tall engine

is very impressive.

The real power of this engineering colossus

comes from Rudolph Diesel's brilliant design,

patented in 1894.

It's very hard to believe that the inspiration

to this piece of engineering came from an object

which actually fits into the palm of your hand.

The internal combustion engine