May 7, 2021

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What Really Happened at the Suez Canal?

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On March 23, 2021, the massive container ship Ever 
Given ran aground in the Suez Canal. The wedged  

vessel obstructed the entire channel, blocking 
one of the most important trade routes in the  

world for nearly a week. The cause and details 
of this event are still under investigation,  

but there’s a lot we already know. 
How could something like this happen,  

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and why did it take so long to fix? I have 
two demonstrations to help us understand.  

I’m Grady and this is Practical 
Engineering. In today’s episode,  

we’re exploring some of the engineering 
principles behind the 2021 Suez Canal obstruction.

Before we get into the event itself, let’s 
learn a little bit about the Suez Canal.  

Built in the 1860s, the Suez Canal 
is a constructed waterway in Egypt,  

allowing shipping and other maritime traffic 
to go from the Mediterranean Sea to the Red  

Sea and vice versa. This means ships don’t need to 
navigate all the way north around the European and  

Asian continents or all the way south around the 
African continent to travel between the Atlantic  

and Indian oceans. It’s basically a global 
shortcut. That makes it one of the most important  

routes for global commerce, handling roughly 
ten percent of the entire world’s ocean trade.

For as important as it is to the global economy, 
the Suez Canal is a relatively straightforward  

structure: essentially a trapezoidal channel cut 
through the sand of the low-lying Suez Peninsula  

and taking advantage of the existing Great Bitter 
Lake at the center. Unlike the Panama Canal which  

uses locks to raise vessels up for transit, 
the Suez Canal is entirely at sea level with  

no gates or locks. Minor differences in level 
between the Mediterranean and Red Seas create  

gentle currents in the canal, but they’re 
not strong enough to trouble the ships.  

In 2016, an expansion to the Suez 
Canal opened, essentially doubling  

its capacity. The project involved adding a 
second shipping lane to part of the canal,  

and deepening and widening some of the 
choke points so larger ships could pass  

through. It’s now about 200 meters (700 feet) 
wide and about 24 meters (80 feet) deep.

All ships passing through the Suez Canal are 
required to have a Canal Authority pilot to help  

navigate each step. These pilots aren’t 
fully responsible for the safety of the  

ship during transit, but they have special 
knowledge about the processes, procedures,  

and challenges required to navigate 
these massive vessels through the canal.  

It’s tricky, and ships have been stuck in the 
canal before, including a 3-day blockage in 2004.  

So, each ship’s Master (sometimes called the 
captain) and the canal authority pilot work  

together to maneuver the ship through. It takes 
about half a day to get from one end to the other,  

and on average, about 50 ships make 
their way through the canal each day.

Navigating through the Suez Canal is a careful 
dance since some parts of the channel only have a  

single shipping lane with no room to pass. That’s 
why ships are required to go through in convoys.  

Early each morning, the convoys line up to enter 
the canal. The southbound group begins their  

journey from about 3AM to 8AM at Port Said, 
following the western channel. At around the  

same time, the northbound convoy enters the 
canal at Suez. On a normal day, everything  

is carefully timed so that the two convoys 
can pass each other in the Great Bitter Lake  

and the dual lane section of the canal without 
any stopping or interruptions. Unfortunately,  

March 23rd was not a normal day. One of the first 
ships in the northbound convoy, the Ever Given,  

had barely entered the canal at Suez when it 
veered into the eastern bank, smashing its  

bow into the sandy embankment and wedging the 
massive vessel diagonally across the channel’s  

entire width. Amazingly, there was not a single 
injury and the cargo was completely unharmed.

As I mentioned, the exact reason the ship 
ran aground is still under investigation.  

Some reporting suggested the Ever Given 
experienced a loss of power, but that was denied  

by the ship’s technical manager. Sources also say 
that there was an ongoing dust storm that morning  

creating high winds and limited visibility. Many 
have suggested that the Ever Given’s unscheduled  

and unfortunate landing in the canal may have 
been hastened by a hydraulic phenomenon unique  

to vessels transiting through shallow water called 
the Bank Effect. Luckily I have an acrylic flume  

in my garage, and I can try to demonstrate how 
this works. But first a little info on this ship.

Leased and operated by international 
shipping company Evergreen,  

the Ever Given is one of the eleven 
Golden Class container ships,  

all confusingly named “Ever” combined with a 
seemingly arbitrary g-word. Weird names aside,  

these ships are truly massive. In fact, the 
Ever Given will never get a chance to go  

through the Panama Canal because it’s too 
long for the locks at 400 meters (or over  

1,300 feet long). This is a cross-sectional view 
of the Suez Canal and the Ever Given to scale. The  

ship’s beam is 60 meters (or nearly 200 feet) with 
a fully-loaded draft of 15 meters (or 48 feet).  

You can see how small the margin for error 
is with a ship this size in the canal.

If you remember your lessons on 
buoyancy, you know that a ship  

displaces its own weight in water. That means 
for every pound of steel and cargo aboard,  

a pound of water below the ship has to 
get out of the way. For the Ever Given,  

that is hundreds of thousands of tons of liquid 
being pushed to either side of the ship as it  

cuts through the water. On the open sea, that’s 
not a problem. The displacement forms a wake, but  

the water otherwise doesn’t have trouble finding 
a new place to go. In a shallow canal, though,  

things are a little different. 
Let me show you what I mean.

My flume isn’t long enough to simulate a boat 
moving through a canal, but if you switch your  

frame of reference to that of a ship, it can 
simulate the movement of water passing by.  

In a shallow canal, all the water displaced by 
a ship has to essentially squish through the  

small areas along the sides and bottom 
of the vessel. The smaller the area,  

the faster the water has to move to get out 
of the way. I’m using some brick pavers as  

my surrogate shipping vessel. Watch what 
happens when I drop them in the flow.

The water builds up at the bow (or front) of the 
ship. As the water accelerates through the narrow  

gaps on either side, its level drops. Obviously, 
this demo is exaggerated from a real situation,  

but this is a well-known phenomenon that creates 
some unusual effects on ships. That’s because,  

in accordance with Bernoulli’s law, a fluid’s 
pressure goes down when its speed goes up.  

When traveling in a shallow area, the squished 
and sped-up flow below the hull creates a suction  

force pulling the ship further into the water, a 
phenomenon known as “squatting”. One massive ship  

even used the effect by speeding up as it went 
below the Great Belt Bridge in Denmark to create  

some extra margin above the deck. But, the exact 
same effect can happen on the side of a ship as  

well. If a vessel gets too close to the bank of 
a shallow canal, the water it displaces on that  

side essentially has nowhere to go. It has to pick 
up speed as it squishes through the narrow gap,  

lowering the pressure, and thus pulling the ship 
toward the bank. It seems pretty straightforward  

when you exaggerate it in a demo like this, 
but in reality the Bank Effect is not that well  

understood. Research is ongoing to better 
characterize how depth, distance, speed,  

propellor action, and other factors can affect 
the way a ship moves in a restricted waterway.  

We still have a lot to learn both in an 
academic sense and in nautical practice,  

a fact made very clear when this massive 
vessel found the edge of the Suez Canal.

Images of the first responder to the accident, a 
tiny excavator removing soil from the Ever Given’s  

gigantic hull, circulated around the internet like 
wildfire. The yawning gap between the machine’s  

assignment and its capability was just too ripe 
for parody – you could hardly check a single  

social media feed without being overwhelmed by 
the memes. In a long period of collective unrest  

and despondency during a global pandemic and the 
seemingly constant uncertainty surrounding who or  

what to believe about so many complicated issues, 
here was a story that anyone could understand:  

A boat was stuck in a canal. It was in the 
way of other boats that needed to get through.  

Simple as that. So why did 
it take so long to dislodge?

Humanity has a long and storied history of 
driving stuff into the ground so it will stay  

put, from the small (like tent stakes) to the 
massive (like the earth anchors used to hold guy  

wires for antenna masts). It’s pretty intuitive 
how this works. The pullout force is resisted by  

the friction between the soil and anchor. This 
ability to resist pullout is a function of the  

pressure against the soil and the surface area 
of the anchor. And when your anchor is a ship  

the size of a skyscraper, you obviously have both 
of those in abundance. It’s really no wonder that  

salvage crews struggled to unstick the Ever Given. 
But, there is a geotechnical phenomenon that I  

suspect made things even worse. And just a warning 
that I’m straying a little into speculation here,  

since the geotechnical details of the 
extraction have not been widely reported.

Soils with large grains, like sand, have 
an interesting property called dilatancy.  

Essentially, when they’re deformed, they expand 
in volume. Watch what happens when I strike the  

top of this sand in my beaker. Notice how the 
sheen of water on the surface disappeared?  

If you’ve ever walked on the beach, this 
is probably something you’ve seen before.  

The water disappears from the surface because it 
soaks into the extra space created when the sand  

was deformed. This dilation occurs because 
the grains of sand, which were interlocked,  

rotate and lever against each other, pressing 
outwards as they do. This would not be a major  

issue except for one detail about the Ever Given’s 
hull: the bulbous bow, a feature included on many  

large ships to reduce drag. The hydrodynamics 
of bulbous bows are definitely worth discussing  

in a future video, but here is why it was such 
a problem for the Ever Given. Unlike if only  

the triangular hull was wedged in the sand, the 
bulbous bow was surrounded by soil on all sides.  

Essentially, the Ever Given put its appendage 
into a gigantic finger trap toy. Any movement  

of the ship would dilate the sand, effectively 
clamping down harder on the bulbous bow.

Ultimately it was impossible to simply pull the 
ship out. Removal took a much more extensive  

operation of dredging the sand from around the 
hull and lightening the ship by releasing ballast  

water, both to relieve the friction from the 
soil. Even the moon joined in on the operation,  

raising the tide in the canal to give a 
little more buoyancy to the foundered ship.  

After six days aground, the Ever Given was finally 
dislodged and traffic through the canal could  

resume. At the time, there were about 400 vessels 
waiting to make their pass and many more that had  

already diverted around the Cape of Good Hope. 
With a capacity of only around 90 ships per day,  

the backlog took about a week to clear up. That 
doesn’t mean the problem is resolved though.  

A weeklong disruption in such a big portion of 
global shipping traffic doesn’t untangle itself so  

quickly. The investigation into the exact cause 
of the incident is ongoing, and I’m sure many  

insurance claims are as well. In the meantime, I 
hope this video helps you understand a few of the  

engineering challenges associated with navigating 
massive ships through tiny canals and what can  

happen when they run aground. Thank you for 
watching, and let me know what you think!

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