- Today's episode was sponsored by Kraken Rum.
The mythical beast known as the kraken
is one of the most menacing, enigmatic
and powerful sea monsters humans have ever dreamt up.
Back I say, not yet.
In stories and tall tales, they prowl underneath
the ocean waves, snacking on fish
and pirates and occasionally using their powerful
tentacles to pull entire ships under the waves.
But how strong would a kraken really have to be
to do that?
(rock music)
Your conception of what a kraken is and does
is probably somewhere between Pirates of the Caribbean
and Clash of the Titans.
But krakens have been circling popular culture
for centuries starting in myths and legends
and reports, eventually making it into everything
from movies to video games to _ the gathering.
The description of a kraken varies
but what is consistent is their ability
to pull ships underwater.
Is there a way to realize this strength with physics?
Well yes, everything can but first, what is a kraken?
A kraken was first rigorously described
in literature by fancy boy Eric _ in 1752.
In his, a first attempt at a natural history of Norway.
Where he said these creatures were sometimes so big
that they were mistaken for island chains and
it is said that if the creatures arms were lay hold
of the largest man of war,
they would pull it down to the bottom.
He probably doesn't sound like that.
Now, don't be mistaken, it sounds far fetched
but at the time these reports were
taken very, very seriously.
We now know that these reports were probably
just people seeing giant squid
or volcanic activity making islands out of nowhere.
But that's fine, we can still focus on how hard
it would be for a kraken to pull something underwater.
Pulling a ship to the bottom of the sea
would take almost an unfathomable amount of ummph.
The reason why starts with Archimedes' Principle.
Archimedes' Principle states that the buoyant force
on an object submerged in a fluid
equals the weight of that fluid that that object
moves out of the way.
For example, if the weight of fluid that is moved
out of the way by a ship is larger
than the weight of the ship itself, the ship floats.
That's how they do it.
But this tension between the buoyant force
and the weight of an object in fluid
is exactly why it is so hard to pull an object
fully underwater.
Here, let me explain.
No really, let me explain.
The buoyant force on a submerged object
can be substantial but you probably already know this
if you've ever played with a beach ball.
Why is it so hard to force a beach ball under the water?
That's because to do so you have to move
a beach ball worth of water out of the way
and water is very, very heavy.
For example, for a beach ball this volume,
I have to force the same amount of water out of the way
as I weigh over 50 kilograms, over 150 pounds.
Then you ride it away.
If that's how hard it is to pull a beach ball
under the water, just imagine how this scales
up to pulling an entire ship under the ocean.
That's something that we can figure out
but we need the same data for large ships
that we had for the beach ball.
Calculating the internal volume of a beach ball is easy.
Calculating the total internal volume of something
as complicated as a ship is much harder.
The best estimation that we have of that value
is called gross tonnage, which is a non-linear measurement
of a ship's total internal volume that sales with size.
We can use this value to calculate how
much water will be pushed out of the way
if a ship is fully dragged under.
But we don't just need the ship's volume,
we need the weight of the ship too.
This is called a ship's displacement
and it's equal to the weight of water
that's pushed out of the way while the ship is floating.
Since floating means that the buoyant force
is canceling out the weight of the ship,
displacement is weight of the ship.
We need this value because it makes a ship
either harder or easier to drag under.
Okay, so all we need to do now is pick a ship,
multiply its total gross tonnage
by the density of sea water and gravity
and from that value, subtract the weight
or displacement of the ship.
This will give us the total kraken force
or the force required to fully submerge a ship's volume.
Alright, now it's time to
release the kraken.
It sounded cooler when Liam Neeson said it.
I'm gonna assume that our kraken doesn't
break any ship apart because if the ship is whole,
that's what will take the most force.
This is the Earl of Pembroke.
It is a decently sized sailing vessel
that was modeled after the ship that Captain Cook
used to discover Australia.
If we use this ship and these numbers I could find for it
for its gross tonnage and its displacement,
then a kraken to fully submerge this ship
and overcome its buoyant force would have to pull
with over four
million Newtons, or 900,000 pounds.
This sounds like a lot and it is.
But if a blue whale could pull with all of its body weight,
it would only take two of them to sink the Pembroke
like a kraken.
Although, whales probably can't pull with their body weight,
so it would take a lot more.
Still, krakens are supposed to be dozens of times
longer than blue whale, so this situation is
plausible.
How about something a bit bigger?
This is the Titanic.
You know the Titanic.
To meet its end by kraken instead of by iceberg,
the mythical cephalopod would have to pull down with over
one billion Newtons of force
over a quarter of a billion pounds.
This is more force than the estimated force
of all of the photons hitting Earth.
It's a lot.
What about a class of ship with more gross tonnage
than any other?
This is a battlis class super tanker
and it's over half a kilometer long.
Let's do the math one more time.
To pull down this beast of a ship,
a beastly kraken would have to exert
over two and half
billion Newtons of force.
This is equivalent to the thrust force
of over 100 space X falcon heavy rockets.
If a kraken could do this,
it would have to make it one of the strongest
mythical beings ever, ever.
How strong is a kraken really?
Well this island sized monster would have to exert
either millions or up to billions of Newtons of force
to drag ships to their doom,
making them incredibly formidable fictions.
If they were able to do this, either with powerful
mantle jets or just strong tentis,
then they would be pulling better than our best rockets
can push.
But of course if they were really smart,
they would just break the ships apart beforehand
and negate all that buoyancy.
Strong and clever, that's what makes them so scary,
Because Science.
(techno music)
Today's episode was sponsored by Kraken Rum.
To release the Kraken, visit KrakenRum.com
and sign up for the League of Darkness
to receive discounts, gifts and special privledges.
Save travels my friends and please remember
to always drink responsibly.
Thank you so much for watching Matt.
If you want even more silliness, you can check out Muskwatch
or if you want even more science, you can check out
the S.P.A.A.C.E Program on ProjectAlpha.com
where if you sign up you can also get Because Science
two days earlier, thanks again.
(techno music)