Speed.
It seems to govern every aspect of our lives nowadays, form the way we travel, to the way we get our entertainment
and even the way we receive information over the internet, like this video!
. But speed was as important during the era of the ocean liner as it is today;
in fact it was speed that even drove the development of ocean liners in the first place.
Luxury was nice, but speed was king
and in the annals of the great fast ocean liners, one name stands head and shoulders above the rest...
That name? SS United States.
But just how do you get a machine almost 1,000 feet long, displacing 45,000 tons of water
up to speeds in excess of 38 knots? – that’s 70 km/h, or 43 mph!
It took some good old fashioned engineering know-how and a lot of problem-solving.
Here's why United States was so fast.
(smooth jazz music plays)
(old film projector starts, 1950s newsreel orchestral music plays)
The story begins in the postwar world, when America’s production capacity was at an all time high
and the nation sought to compete against the giant liners of Europe like Queen Mary, Queen Elizabeth and Liberte.
America's answer to this was the SS United States
A ship which was not luxurious in the traditional sense, but was stylish in a Mad Men kind of way
but most importantly she was quick; speed was her very essence, in her DNA.
The US government underwrote about 2/3 of the ship’s construction costs, that is 50 million of 78 million dollars
and subsidized her operations in the hope that she would be used as a troopship in the event of a war with the Soviet Union.
This is because the United States navy had been impressed by the performance of Cunard’s Queens in the Second World War.
Of course until that point, Queen Mary had been the reigning Blue Riband holder for almost 15 years. Now it was America’s turn.
But wait, before we go any further, I need to introduce you to somebody.
This is William Francis Gibbs, one of my favourite characters from maritime history of all time.
He had set out initially as a young man to become a lawyer but quickly found himself drawn to ships and naval architecture
his college room ended up covered with rolled up plans of battleships and ocean liners.
He practiced law for two years but began designing, with his brother Frederic, a 1,000-foot long ocean liner and in 1915 he left law for good.
What followed was a stellar career and the Gibbs name is attached to some of history’s greatest liners from the Leviathan
to the beautiful Matson liners of the 1930s.
He was an eccentric; stern and cool, and he watched over the construction of his ships like a hawk.
He was obsessive, agonizing over every detail and taking lessons from ships that had come and gone before.
From Titanic, he drew lessons about compartmentalization and, in typical Gibbs fashion, took it to the next level. His ships were the safest afloat;
in 1927 the SS Malolo was on her sea trials when she was heavily rammed by a freighter.
The collision opened up Malolo’s hull and 7,000 tons of water poured in. Any other ship would probably have sunk;
except Malolo was designed by Gibbs and she stayed afloat. He was even on board that day to watch the whole thing unfold.
So Gibbs turned his eye to the design of a great American Blue Riband-winning ship
But in order to pull it off he had a few problems to solve;
One, to design the most efficient hull form possible
And two, to outfit it with the most powerful engines afloat.
Easy-peasy!
First up; the hull design.
Gibbs and his team would have to come up with something radical if the ship was going to break speed records
to do it, as always, he’d borrow a little from ships of the past.
In overview the SS United States’ proportions are extremely lean;
the ship has a long, elegant profile and relatively little superstructure above the hull.
She was 990 feet in length, with a beam of about 101 feet and a draught of 31 feet.
Her hull was divided into 20 watertight compartments
with fuel and ballast tanks extending up the sides of the hull to create a second skin.
This was classic Gibbs overdesigning; the ship would remain afloat with as many as five of these compartments flooded
and one additional safety measure gave away her naval pedigree.
The ship featured two separated engine rooms, a practice commonly found on warships
so that in the event of a torpedo strike or shell hit, the ship could move under her own power if one was knocked out.
But, going back to that hull shape - what's so special about it in the first place?
To understand this we have to turn the pages back in our history book a couple of years.
The revolutionary German liners Bremen and Europa had created a sensation
when they stole the Blue Riband from the old Mauretania in 1929 and 1930.
Gibbs paid close attention to their hull form and general proportion
stating that there was “the remarkable agreement in length and beam”.
Gibbs had also learned a lot from the design and construction of SS America before the war
chief among which was the ship’s shape below the waterline.
The ship had a low prismatic coefficient, with narrow, tapered ends a wider midsection prioritizing speed for stability.
The higher the prismatic coefficient, the blockier and less efficient the ship is in cutting through the water.
Gibbs decided to give United States an extremely low coefficient of .559 with an even narrower bow and stern than America.
From the German superliners Gibbs borrowed a slight bulbous bow to reduce drag as the ship ploughed through the waves.
For this reason too her prow was heavily raked forward. On the SS America the prow had raked before dropping vertical at the waterline
creating drag and slowing the ship down. The United States’ bow would be raked all the way down;
even to a casual observer, the aggressive angle said that United States was a ship going somewhere in a hurry!
When the SS America was completed in 1939 she was a major coup for Gibbs and the ship’s owners, United States Lines
but she was ultimately dwarfed by the European superliners. United States would be much bigger.
As always, military matters guided the ship’s design so in order to function as a troopship in wartime, United States would have to squeeze through the Panama Canal,
a feat which neither Queen Mary nor Queen Elizabeth could accomplish.
This limited United States’ beam and overall size; but this wasn’t a problem, because Gibbs and his team recognized that bigger did not necessarily mean better.
United States would be far bigger than SS America; but smaller than Queen Mary.
Referring to the likes of Queen Mary and Normandie, Gibbs said, perhaps a bit harshly, that:
United States would be a speed demon to be sure; but she would not be breaking any size records.
To reduce drag and enhance United States’ speed Gibbs also gave his ship a very shallow draught; just 31 feet of the ship’s hull would be below the waterline.
Compare that with America, which was about 50% smaller overall than United States but whose draft was a whopping 33 feet.
Queen Mary, about 34% bigger than United States, had a monstrous 38 foot draft.
A bigger draft helps make a ship more stable, so United States had to be designed with the lowest centre of gravity of any liner afloat.
To even accomplish this required an ultra-lightweight superstructure. To this end Gibbs employed the use of aluminium
on almost everything structural above the hull, from the lifeboats and their davits to the enormous funnels and deck ventilators.
It was the largest use of aluminium in a single construction project up until that time.
Its use meant there would also be no need for expansion joints, a common feature on old liners which were prone to creaking, leaking and cracking.
(thunder clap)
So Gibbs and his team had designed a long, lean hull that could slice through the ocean like a knife in any kind of weather.
An oceanliner can’t just slow down when it’s stormy; it needs to batter its way through
and United States was designed to do just this.
With the hull design sorted, the team looked at the second big factor behind United State’s speed prowess
which would go on to become a state secret, guarded carefully by the navy for decades.
To understand this, we need to go and look below the waterline…
The Big U would need a monstrous propulsion system and turbine engines seemed the obvious choice.
Among hundreds of other ships, they had driven Queen Mary at enormous speed in her Blue Riband-winning voyages.
But United States’ engines would be more powerful; much more powerful.
But here Gibbs had a problem; how do you fit giant turbine engines in the leanest hull of any ocean liner?
Gibbs had an ace up his ; After years of wartime experience, developing some of the most advanced fast battleships and destroyers afloat,
American turbines were simply smaller and more powerful than their British or European pre-war counterparts.
In this top-down view you can see a slice of Queen Mary's hull at about the engine room.
You can very clearly see a traditional boiler and engine room arrangement.
But here, taken from a similar spot in the United States' hull, it's very clear that her machinery takes up far less space
and the split engine room design is very apparent.
Because of this, unlike the SS America, both of her funnels were fully functional; with huge uptakes removing smoke from both the forward and aft boilers.
While Queen Mary’s engines output 158,000 horsepower at full steam United States could manage 240,000 shaft horsepower
using steam superheated to 850 degrees Fahrenheit. That's 450 degrees celcius!
If a crack or leak developed in the steam lines, anybody standing nearby would be instantly and horrifically scalded.
It was a high-risk-high-reward type scenario.
At full power United States’ turbines would be turning at 5,800 revolutions per minute.
it was then up to her double reduction gears to channel this enormous brute power and slow it down,
first to 3,200 rpm and finally 180 revolutions per minute for the propeller shafts.
That was a reduction ratio of thirty to one, and any gears less solidly built would have fractured or sheared under the enormous strain of 200 tons of thrust on each propeller shaft.
Speaking of propellers, here lies the final secret to the United States’ speed.
The 'Big U’s enormous 18 foot diameter manganese bronze propellers were a work of art unto themselves
and their conception and design had been left in the hands of a promising young engineer who Gibbs hand-picked himself.
Her name was Elaine Kaplan.
I don’t need to tell you that the 1950s were a pretty tough time to be a lady
and virtually all professional fields, especially engineering, were staffed entirely by men.
It’s remarkable that Kaplan’s sheer engineering prowess and ability had earned Gibbs’ trust and begrudging respect.
Leading her team, Kaplan developed a set of four sleek and aggressively swept screws.
Initially she had intended for the liner to have two pairs of four-bladed propellers but then disaster struck.
At testing the team discovered that United States would suffer badly from vibration and cavitation at speed.
Cavitation is a phenomena where a propeller, if incorrectly shaped and designed, is driving through the water at force creating negative pressure as it spins.
This can disrupt flow over the propeller and create bubbles on the propellers surface which results in vibration and a loss of thrust.
Those little gas bubbles can even eat away at the bronze propeller leaving permanent pitting and damage.
Many turbine-driven liners had fallen victim to this, from Lusitania to Normandie
and dozens of propeller re-designs and endless testing hardly rectified the issue.
Elaine Kaplan now faced the same problems; despite altering the pitch, or angle, of the ship’s propeller blades
the results were the same and United States would vibrate unacceptably.
Kaplan and her team went back to the drawing board and turned to lessons learned from the Second World War.
They found a solution which had been used on the Iowa class battleships of the US Navy.
This novel arrangement made use of mismatched propellers
The outboard set having four blades and the inboard set five.
The extra blade on the inboard set of propellers meant they would better churn through the water already disturbed by the set of propellers ahead of them.
Cavitation wasn’t totally eliminated from the ship; today, you can see damage to the propeller blades caused by gas bubbles.
But the clever design solution meant United States would have a cracking top speed and the effects of vibration would be barely noticeable.
The stern section was shrouded in secrecy and the publishing of photographs forbidden.
The United States was completed in 1952, the combined result of 7 years of careful planning and design.
On her sea trials, Gibbs and the team held their breath as she worked up to speed; engines turning at full steam
and even in a near-gale, the huge ship hit 38 knots. It was a total triumph!
The United States exceeded initial proposal and achieved the fastest speed hit by any ocean liner before or since.
This combination of engineering know-how and taking lessons from older designs
resulted in a ship whose speed was the stuff of legends. She would go on to have a long and successful career,
carrying four US presidents, dozens of celebrities and starlets and thousands of travellers, from holiday-makers to immigrants across the Atlantic.
She stole the Blue Riband on her maiden voyage and keeps it to this day.
She was Gibbs’ pride and joy, America’s flagship.
The fastest ocean liner of all time.
Ladies and gentlemen, it's your friend Mike Brady from Oceanliner Designs. Thanks so much for watching!
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