That's correct, yes.

Okay, all right.

Gav: It looks like someone's just

pulling on space time.

- ( grunts ) - Not really sure what I'm looking at.

Dan: Bath time.

Gav: Those ducks just went--

Dan: Whoosh!

Gav: How do you feel about taking it

right in the face?

Gav: Dan, are you nervous?

- Oh. - ( water splashing )

- Gav: ( chuckles ) Oh! - ( laughter )

Well, that was a very unique

building we had access to there.

I love the fact that they just let us

mess around with it.

It's this incredibly scientific and precise

equipment and they were like, "Go wild."

Your life jacket going off,

unexpectedly, almost wet myself.

I think I even said, I was like,

- ( chuckles ) - "Huh, I'm surprised

this hasn't gone off."

and then about two seconds later it--

- ( air whooshing ) - Both: Whoa!

Both: ( laughing )

I think they're activated by salt

aren't they? Like it dissolves and

- then it activates-- - Yes, the salt in there

to make salt crystal, yeah.

Did it hurt taking the spike wave in the mouth?

- ( water splashing ) - Ooh!

Dan: I thought it was going to,

but it actually didn't.

I really liked that shot where

- ( music playing ) - it sort of tunnels

around your face, you look like you're

in a weird room that's moving.

Dan: Totally surreal. No one had done

that before, it was quite an honor really

to be the first smashed in the face with it.

Gav: Yeah.

So I think it'd be a good idea

if we learned more about waves in general,

but also learn a little bit more about the facility.

So we had a little chat with Tom.

Dr. Thomas Davey, you're the Senior Experimental Officer here.

Yeah, that's correct, yeah.

Okay, so, you can tell us all about

what you do here essentially.

Yes, so this is a facility which essentially is

just a model sea, about 20th scale.

And we we use that for lots of applications,

testing things like wave energy devices,

tidal energy devices.

Basically anything which we put in the sea.

Okay, so if you make a small wave about this big in here,

you imagine it's 20 times the size.

That's what you're imitating essentially in the ocean.

- Dr. Davey: Exactly. - Dan: So how long did it take to fill that thing?

Uh, it did take us three weeks, so--

- Three weeks? - ...we don't like taking the water out of it.

It's two and a half thousand tons of water in this tank.

And what was the choice behind making the tank

this specific size?

If you go much bigger,

things start to get very expensive.

If you go much smaller the scaling

will start to work against you, uh...

- I imagine this was cheap, then. - ( laughs )

Yeah, so you're looking at

about 6 millions pounds of investment

just to build the tank.

And actually the whole project's probably around

12 to 15 million.

Might be one of the more expensive things

- we've messed around with... - ( laughs ) Yeah.

...if I'm honest. Cool.

So how do you get the waves to do

the exact thing you want them to?

Well, this is the only large circular wave

and tidal tank in the world.

So what we have is 168 wave makers around the edge.

These are basically paddles.

So each individual paddle on its own can generate a wave.

But because we're in a circle,

you can imagine, you can actually then generate from any direction,

so you can have this one wave going in one direction,

you can have thousands of waves going from all directions.

It's a bit like playing a musical instrument.

You just combine all these notes together

to create a very complex sea in the tank.

- Whoa-ho-ho-ho! - Whoa!

( water splashing )

And then on top of that you then put tidal currents.

So you make currents as well underneath...

Dr. Davey: Yes, yes. It works a bit like a conveyer belt.

The current comes from underneath the tank,

over the top, and back around again.

- Oh, okay. - So...

You said you can replicate any part of the sea.

If I said to you, I want to replicate Brighton.

I want Brighton, could you do that for me?

As long as you got the data.

If we could get good data for a site

and we can understand the energy of that site

and the directions of the waves and so on, then yes.

That way, if you just brought in a load of sand,

and people didn't fancy the, like, eight hour drive,

you could have people just come in here

- and enjoy the-- - Yeah, we'd be in the surfing business.

( laughter )

Thanks, Tom, that was really interesting

and thanks for letting us use your very expensive pool.

Dr. Davey: No problem.

Back to you, Gav and Dan.

Thanks, us.

Why don't we learn some more about waves.

Yeah, we've invited someone along

who's travelled the world,

and written a book about all the world's

scariest, largest, fastest waves.

It's called "Tides."

Hi, Jonathan. How's it going?

- Hi, Dan. - Hey.

Could you explain to us, the difference between waves and tides?

Sure, waves, as we talked about

are generally created in the storm, right?

There's a one pulse that makes the wave

and then the waves travel away from that.

But a tide is actually also a wave,

but it's the largest wave on the planet.

And it's a long low wave

that travels about 450 miles per hour around the globe.

We don't experience it as a fast moving phenomenon

because if we're on the coast, we have to stay there all day

to watch it pass, right?

Six hours of trough, which is low tide,

and then about six hours later, the crest, high tide.

So you could potentially be on a plane,

unknowingly flying at the same speed

- as a tide rolling through. - That's right.

The oceans actually aren't deep enough

for this free wave, this wave of tide, to travel

as fast as it wants to travel.

So essentially it drags its legs

on the bottom of the ocean,

and slows down and creates friction.

Friction against the entire Earth?

- That's right. - Wow, yeah.

'Cause I've heard that they occasionally

will add like a leap second to the clocks

to compensate for the Earth slowing down.

Tides have literally slowed down the rotation of the Earth.

Acted as a break.

'Cause the tides are slowing down the world

by friction on the bottom of the sea.

That means every millions of years,

there's changes to the amount of hours in a day?

Yeah, about 400 million years ago,

our day 21 hours long, not 24.

Because of the tide.

I'm okay with it, because I feel like

I'd struggle to fit everything into a 21 hour day.

Yeah, so you're thinking that millions of years

when it's a 30 hour day,

- people are gonna be like... - ( laughs )

( sputters ) ...a long day.

Yeah, the days got longer and then people started having longer meetings.

- ( laughs ) - That's what happened.

Yeah.