The Titanic saga is well-worn and it has been told a million times - if you’ve
ever watched a documentary on the ship you’ve probably heard metaphors about icecube trays
overflowing and heard all about watertight doors, compartments, rivets and all that.
But what does it all mean? Why wasn’t Titanic designed to withstand the iceberg?
What exactly caused the ship to sink so quickly? How can ice damage steel? Well today let’s take
a close look at all this and more and find out just how the iceberg sank the Titanic.
To answer this question we have to look at the events in four steps; first, the ship’s
design. Second, the events. Third; the damage and fourth, the aftermath. Let’s get started.
First some quick context. Titanic was designed and built by an incredibly experienced team
of engineers, builders and artisans and even though heralded as the world’s largest ship - at
the time - the Titanic was actually built in an almost identical manner to hundreds and hundreds
of other ships. You see, Harland and Wolff - the shipbuilding firm in Belfast - had been
building ships since 1861 and they were pretty damn good at it. In fact they were up there as
one of the best shipbuilding firms in the world. They were the builders of choice, not just for
Titanic’s owners the White Star Line, but dozens of other shipping lines like P&O, Union Castle,
Furness Bermuda, Royal Mail and many more. But a long-standing agreement saw White Star Line
commissioning virtually every one of their ships to be built by Harland and Wolff. One of the many
stupid myths about the Titanic disaster is that Harland and Wolff was a cost-cutting organisation
and built their ships out of sub-standard materials. It’s just not true. They’d been doing
this for a long, long time and knew their stuff; and they were extremely proud of their product.
So when White Star Line began discussing plans for a trio of super-liners early in about
1907 or 1908, Harland and Wolff was all ears. They knew they’d have to overhaul
their entire shipyard to accommodate the massive engineering task so they knocked down
all their old slipways and built a monstrous gantry to support cranes and build the new ships
as well as a cavernous graving dock to fit the ship out once it was afloat- oh look there’s me!
The reason I’m telling you all is this because I want to try to highlight something for you;
Titanic, and her two sisters Olympic and Britannic, were not really that special.
Yes; they were big. Really big for the time. But Harland and Wolff wasn’t going
to re-invent the wheel on this project. They took what they had built on a smaller scale;
ships like White Star’s Oceanic, Laurentic and Adriatic - and scaled the designs
way up. So if you can understand how Olympic and Titanic were built - then you really know
how almost every Harland and Wolff ship was built in the lead-up to the 1920s.
So when White Star began talking about advanced safety features for the new ships Harland and
Wolff was happy to oblige because up until only relatively recently by then, travel at sea was
a bit of a gamble - fairly regularly ships were lost in storms and just never showed up.
White Star Line cut its teeth on the run to Australia - that was a particularly dangerous
route and the worst 19th century loss of life in Australian waters happened after
4 months at sea when the ship was just one day away from docking safely in Melbourne.
So the travelling public was a bit apprehensive about travel at sea. It didn’t help that in
1909 White Star lost a ship, the Republic, when it was rammed and sunk off Nantucket.
White Star and Harland and Wolff would go above and beyond to make Olympic and Titanic as safe
as possible - safer really than any other ship afloat - and then market the hell out of it.
So - what does this all have to do with the design? Well, let’s look at how Titanic was
built from the ground up. Titanic’s hull was a giant box girder; if you can picture it that
way then all the individual components will make sense. Box girders are immensely strong and they
are ideal for resisting torsion, or twisting, which is very useful in ships because they are
very long and prone to flexing and twisting while going over big waves.
Box Girders require four “walls” to function. In Titanic’s case, the bottom wall was the keel, the
top wall the strength deck and the two side walls the hull. Here’s how it was built. First, the keel
was laid - this is essentially the ship’s backbone - it comprised a keel plate which sat flat on the
slipway’s blocks - and then a girder which ran most of the length of the ship. Then along the
length of the keel were fitted these things called ‘floors’ - they provided the something for more
longitudinal girders to be riveted to - and slowly the width of the structure increased until you had
an immensely strong steel skeleton. The bottom of this was plated. The steel plates basically formed
a watertight skin for the ship. They were made of steel and were surprisingly thin; on Titanic
the plates ranged from .64 of an inch - 1.6cm - to about 1.25 inches or 3cm. The bottom of Titanic,
under the keel, was where the heaviest plates were used - those 1.25inch plates I just mentioned.
Now on earlier ships this is kind of where the yard would move on to the next step, but by
Titanic’s day things had developed a bit and the ship was given a ‘double bottom’. This basically
involved riveting a second watertight skin of plates on top of the keel structure. The ‘deck’
this created was called the Tank Top, and for good reason, because the space in between the plates on
the bottom of the keel and the plates on top oat the tank top was subdivided into tanks for ballast
water. The reasoning for this simple; ships for as long as they had existed, had been bumping into
things. So there was a lot of knowledge around the kind of damage a ship was likely to encounter.
Grounding damage was some of the worst - in fact, Costa Concordia fell victim to this in 2012.
If Titanic encountered shallow rocks or something they could pierce the bottom plating
and open the ship’s hull up to the ocean, sinking it quickly. The second layer of plating on the
tank top would prevent this from happening. Crucially though; the second row of plating
ended there. It did not continue up the sides of Titanic’s hull. But we’ll get to that in a minute.
Next, to the floors were riveted giant frames which began to form the hull,
the side floors of the box girder - these were forged steel beasts multiple storeys tall,
bent into the correct shape to give Titanic’s hull it’s streamline hydrodynamic form - and they ran
the length of Titanic’s hull spaced out every 24 to 33 inches depending on their location. To these
frames were riveted the majority of Titanic’s hull plates; basically the external skin of the ship.
From here up, the plates which weren’t part of the double bottom were a little bit thinner. This was
to save a bit of weight and give the ship greater flexibility while rocking and rolling through a
storm. Each plate had rows of rivets hand-driven into each edge. The rivets were wrought iron,
pushed red-hot in place and then hammered home until they fastened two plates together. 3 million
were used to construct Titanic’s hull and every single plate edge was dotted with dozens of them.
If you were standing in Titanic’s boiler or engine room, way down at the bottom of the ship,
you’d be standing on top of the tank top. Looking to the side you’d see big frames just where they
curve to join the keel and its floors - and you’d see plates. There is nothing between those plates
and the ocean on the other side. There’s not a second layer or inner skin or anything like that.
Finally to give the box girder it’s roof the reinforced strength deck, which on Titanic
sat at B-Deck, was riveted into place and all the subsequent decks below it.
Remember when I called Titanic’s hull a box girder? Here’s an actual box girder design,
a cross section of the tubular Britannia bridge. Looks familiar, right?
Okay - so Harland and Wolff have the hulk of a ship. At the moment it’s safe from damage to the
bottom in, say, a grounding. But what if the ship is hit from the side? An impact from a collision
would mean water could flood the hull and sink the ship in minutes. No, something had to be done to
prevent this. It seems incredible that the idea of watertight compartments was kind of revolutionary;
for hundreds of years ships had just sailed around without them.
Titanic took the idea to the next level. Titanic’s hull was divided into 16 compartments - basically
massive self-contained rooms, by 15 bulkheads which were basically heavy-duty steel walls
that ran up the hull as high as practicable. These were made of steel plating and, of course,
ran through some passenger and crew areas in the lower decks. This meant that to get through them
there had to be some kind of doorway fitted that could be sealed up in the case of an emergency. On
Titanic, this came in the form of the watertight door and Titanic had a couple of different types.
First is probably the most famous; seen here dramatically closing in the 1997 movie Titanic.
These ran on rails and closed downwards. They were made of heavy cast iron and in the boiler
and engines rooms had to be wide enough for men to pass through with coal-carrying wheelbarrows. The
doors were held open by a clutch; this could be released automatically by switches in the bridge
or individually by simply lifting a hand-lever connected to the clutch.
Each door could also be closed manually by hand-cranking it shut from the deck above.
One final safeguard was installed; in the event of flooding, a float would raise the lever
and disengage the clutch, lowering the door. The doors were designed to lower slowly at first
so men could get out of the way, but for the last 18 or 24 inches would drop suddenly like
a guillotine to create a watertight seal. This guy would have been in big trouble.
The second kind of watertight door closed horizontally, or laterally and these were
the ones found in most of the passenger and crew areas on Titanic’s lower decks.
These had to be hand-cranked shut either on-site or from the deck above.
The watertight bulkheads had as few openings as possible and, when the doors were shut,
created a compartment with four watertight surfaces; the tank top, the hull sides and the two
watertight bulkheads. However; there was no top watertight surface. The decks above weren’t made
watertight because the bulkheads rose fairly high up in Titanic’s hull above the normal waterline up
here on E-Deck. With this system in place, Titanic could survive a number of theoretical disasters.
If hit by another ship from the side, two or three of Titanic’s compartments would flood;
but the ship could float because the water could flood only about as high as the top of
the watertight bulkheads. If the ship received damage to the first three or even four of her
compartments, say in a side-swipe collision or impact - then the water also could not flood
any higher than E Deck before the ship found equilibrium, the flooding would stop, and the
ship would survive - although it’s bow would be pretty low down in the water. Basically, Titanic
was designed to withstand any and all of the kind of damage any ship had experienced up until that
point. Bow-on collisions, groundings, impacts from other ships; Titanic could survive them all. She
was almost… what’s a good word here - unsinkable? Unsinkable. That’s a good one, let’s use that.
Part 2 - the events. Just before midnight on April 14th,
1912 Titanic’s lookouts and bridge spotted an iceberg ahead at around about the same time.
The ship only had seconds to react and it was just too late; instead of striking head-on directly,
Titanic’s rudder had moved the nose of the ship away from the iceberg by a few degrees so the
berg scraped past along the side. Rushing to the bridge from his adjoining stateroom,
Titanic’s captain Edward Smith now had to diagnose his ship and gauge exactly what the situation was.
He ordered the watertight doors closed but First Officer William Murdoch reported he had already
thrown the switches, so the vertical-closing doors down in the boiler and engine rooms were shut.
Then he ordered the ship’s 4th Officer, Joseph Boxhall to go below and check for damage
and eventually the ship’s carpenter. Already Titanic was exhibiting some strange symptoms;
one of the ship’s lamp trimmers walked up on deck at the very bow of the ship because he could hear
a hissing noise. Up at the forepeak of the ship, the very front, was a vent for one of the ship’s
tanks; the peak tank. This was the forwardmost tank on the ship and in order to be able to trim
the level of the ship and keep it on an even keel, it could be filled or emptied of seawater. The air
had to be displaced, so the vent allowed air to escape out. But now it was loudly hissing,
indicating that the forepeak tank was taking on water at an alarming rate.
Just aft of this area, in the cargo hold, Boatswain’s Mate Albert Haines was investigating
for damage and he could hear water rushing in; the number 1 cargo hatch ran down into
the belly of the ship and at certain levels was covered with tarpaulins or grates. He found that
the tarpaulin was being pushed up by air as it escaped upwards, displaced by the water. This was
all reported to the bridge; to Smith this meant that two watertight compartments were already
opened to the ocean and flooding. Then there came more bad news; boiler room 6 was flooding rapidly;
so rapidly, the crew had had to escape up emergency ladders to get out of the way of water.
That made at least 2 compartments flooding; then came news from the post office. This was located
up on G-deck and had a mail sorting room just one deck below on the Orlop Deck. Ten minutes after
the collision, water began to flood the mail sorting room on the Orlop Deck and the clerks
began to shift mail as fast as they could to save it. This mail room was located in the watertight
compartment forward of boiler room number 6; that made four compartments open to the ocean.
Finally, Smith went below to check the damage for himself; cargo holds 1,2 and 3 were flooding.
Boiler room 5 had a small hole and it was flooding too, just slower. About 20 minutes after the
collision, the Squash Racquet court was reported to be flooding. It painted a disturbing picture
for Titanic’s commander and officers; the forepeak tank taking on water;
cargo holds 1 and flooding rapidly, cargo hold 3 flooded and water now lapping in the Squash court,
boiler room 6 flooded and boiler room 5 taking on water. This spelt the end for Titanic;
the ship was designed to stay afloat with four of those compartments flooded. But now,
with the bow of the ship being pulled down by the weight of water in five compartments, it was past
the tipping point and water would surge up over the bulkheads because of course the top of the
compartments were not watertight. And this it did; by about 12.45 am, around an hour after
the collision, Steward Joseph Wheat found water pouring down the E-Deck steps which led down to
the Turkish Bath one deck below. This meant that water was coming up over the watertight bulkhead
separating the damaged boiler room 5 from boiler room 4 below and flooding aft into the ship.
3. The Damage So what happened to cause this
kind of wide-spread flooding? I mentioned earlier that Titanic didn’t hit the iceberg head-on and
that it managed to turn a couple of points and get it’s nose out of the way of the iceberg ahead.
This meant that Titanic’s side brushed up against the iceberg and suddenly the ship’s entire 40 or
50,000 ton mass was grinding up along the ice. That ice, by the way, is extremely compact glacial
ice; very dense stuff. By contrast, Titanic was - well - a bit squishy. Steel bends quite a bit
under pressure. If you look at photos of Titanic’s sister ship Olympic after a 1911 collision,
you can see the steel plating bent like wet cardboard and rivets popped out of place. The
rivets on Titanic was immensely strong but when the ship came into contact with the iceberg a huge
amount of pressure was put on them and they likely burst in some sections allowing the hull’s plates
to open up ever so slightly and allow water in. It wasn’t a dramatic tear hundreds of feet long;
if that was the case, Titanic would have sunk in minutes and not over two hours. No,
it was a series of small cuts in the hull plating and thanks to sonar imagery and the damage reports
from the night, we have a good idea of where they were. The first cut probably appeared here,
in the region of the forepeak tank. This caused the hissing noise that could be heard
as it flooded with water. Next, a 5 and 6 foot gash were both put into Cargo Hold number 1.
Then the seam of plates in cargo hold 2 opened up for about 16 feet.
Just after this, between cargo holds 2 and 3, a 33 foot gash opened up Titanic’s fourth watertight
compartment - and finally just aft of this, a big 45 foot incision opened up Boiler Room 6
and a little bit of Boiler Room 5. The plates could only have been separated
by about as little as a half inch to 6 inches but these openings were enough to doom Titanic.
4. The Aftermath The immediate shock and outrage caused
by the disaster initiated wide-sweeping changes to the way ships were designed and built for the
next few decades. The most obvious solution was to install a second ‘inner skin’ to the hull - like
the double-bottom but running up the height of the boiler and engine rooms. This modification was
made to Olympic and was built into Britannic, the third sister ship. Then the watertight bulkheads
were raised higher; on Olympic, these went as high as B-Deck - the strength deck - but it
also meant now, in public spaces, there had to be installed the horizontal-closing watertight doors.
After the disaster, the general consensus somehow became that a 300-foot long gash in the Titanic’s
hull had been ripped open by the iceberg but this just wasn’t possible because such extreme damage
would have sent Titanic to the bottom way faster. It was Edward Wilding who first postulated that
the ship’s damage had been intermittent; “I cannot believe that the wound was absolutely continuous
the whole way. I believe that it was in a series of steps, and that it was the end of one of these
series of wounds which flooded the different spaces." - referring to boiler rooms 5 and 6.
In 1986 Wilding may have been proved correct; Dr Robert Ballard observed what little could
be seen of the area that made contact with the iceberg and found plate damage;
a 45 foot long opening about 1 to 6 inches wide in the seams of the plates. This was the one
that directly opened up boiler room 6 and part of boiler room 5 - the incision that doomed Titanic.