Blog 149 - Marine Musings - TITANIC - PART IX - AN ICEBERG’S TRYST WITH THE TITANIC

TITANIC - PART IX - AN ICEBERG’S TRYST WITH THE TITANIC

Tip of the Iceberg - an oft repeated term to signify that what we are seeing is a very small proportion of the whole picture.

This is because, on an average, only about 10% of the iceberg shows itself above the water. 

There are different forms of ice accumulation at sea. As far as the habitable and much frequented areas are concerned, the North Atlantic is one such area, where ice floes of different forms are prevalent.

Before going any further, it is necessary for the reader to understand that ships of today are built according to the terrain in which they will be operating. For example, ships that operate in ice prone areas would have been built to withstand minor collisions with ice packs and are known as ‘Ice Class’. They should not be confused with ‘Ice Breakers’ - they are in a class of their own.

An Ice Breaker at Work

An Ice Breaker Vessel Design

For example : Lloyds Register have certain symbols for the ships that come under their Classification.

 ✠100A1 classification: 

The  ✠ is actually known as a Pattees Cross and signifies that the ship was built under the surveys and supervision of Lloyds from the start.

The ‘100’ means the ship is suitable for service at sea.

‘A’ is for acceptance into Lloyds.

‘1’ is an indication that the vessel has good mooring and anchoring equipment.

Moreover, if ‘1’ is followed by ‘A’ or ‘B’ or ‘C’ or ‘AS, it signifies that vessel has been classed - strengthened - to navigate in ice of various thicknesses found in the Baltic. 

1C - Ice thickness 0.4 mtrs

1B - Ice thickness 0.6 mtrs

1A - Ice thickness 0.8 mtrs

1AS Ice thickness 1 mtr - highest rating for commercial vessels.

Each Classification Society have their own symbols.

The vessels with these symbols would have been strengthened, especially in the forward areas.

I have had the experience of sailing in a non - Ice Class ship, carrying urgent cargo to an ice bound area / port in Canada. What would, normally, have been a 17 hour passage during summers, turned into a 6 day passage. We got stuck in the ice 4 times and each time an Ice Breaker (Canadian) had to come from afar to rescue us. 

Although it seemed a bit adventurous to see ourselves surrounded by fields of ice, we understood the dangers of the situation. All we had to do was lower the gangway and we could walk on the ice floe. But we resisted the temptation. We faced the consequences of being stuck in the ice later. Our propeller had torn the edges of all her blades, impacting with small ice floes. We had to crop all the blades , after which she never got back her speed.

Unfortunately, the Titanic had no strengthening for any type of ice.

She had a soft stem. 

And surprisingly, she was not classed by any Classification Society.

(Today’s rules for ships make it mandatory for any and every ship to be associated with a Classification Society, be they national or international).

Ice is in different forms:

The different forms of ice need to be understood and their dangers to ships and shipping evaluated. (Here I have taken the help of ‘Google’, as I do not claim to be an expert).

Ice is classified by type and by thickness.

There is Pancake Ice, Brash Ice, Floes, Fast Ice, Pack Ice, Drift Ice and others.

The Making of an Iceberg (from ‘Smithsonian’)

When snow falls, the properties of water perform a delicate dance. Snowflakes fall like dominoes fall. A piece of dust forms a crystal, and the appearance of that crystal attracts more crystals until they form long dendrites around the speck of dust like ants around a piece of chocolate. As long as the growing snowflake remains lighter than air, it will float. But as soon as one extra crystal crosses the tipping point, the structure will succumb to gravity and fall.

Snow that started as flakes gets transformed to dense glacial ice as it moves quickly, about four miles per year, toward the west coast of Greenland. Ice weakens as it nears the coast, because every day, particularly in the summer, enormous walls of ice flake off the glacier and fall into the ocean.

The frozen water of these glaciers is slowly forced westward towards the sea by winds, currents. When they finally reach the coast of the Arctic Ocean, the lapping tide break off chunks of the ice and ice bergs are ‘calved’ from the glacier.

These are the Icebergs which are pieces of fresh water ice that have broken off from a glacier and are floating. Any piece of floating ice more than 15 mtrs long can be called an Iceberg.

The size of an Iceberg is limitless. As recently as the year 2000, an iceberg measuring 300 kilometres x 40 kilometres was seen off Greenland.

Icebergs have their genesis when they break off from massive glaciers and fall into the sea. Being free, they start floating.

“Typically about one-tenth of the volume of an iceberg is above water, which follows from Archimedes's Principle of buoyancy; the density of pure ice is about 920 kg/m3 (57 lb/cu ft), and that of seawater about 1.025 kg/m3 (64 lb/cu ft). The contour of the underwater portion can be difficult to judge by looking at the portion above the surface.”

Under the surface, the iceberg’s contours can be jagged or smooth. Depending on the size, the salinity of the water, the temperature of the water and of the atmosphere, the iceberg will melt according to the conditions.

There is an area in the east coast of Newfoundland called Iceberg Alley, where, on an average, about a 1000 icebergs float past from late May to late June every year.

An Iceberg floating past ‘Iceberg Alley’

Majestic Iceberg Floating in Arctic Ocean with Underwater Section Visible - Note the sharp, jagged underwater edges 

Genesis of the Iceberg that collided with the Titanic

The iceberg that sank the Titanic likely originated in the ice fjords on Greenland's west coast, most likely the ice shelf in Ilulissat. The iceberg likely calved in the autumn of 1911, but was related to a warm and wet year in Greenland in 1908.

The iceberg photographed on the morning of 15 April by the chief steward of the Prinz Adalbert who, before even learning of the collision, noticed a red smear along the iceberg's base

Thousands of years pass for the glaciers to form. But the life of an iceberg that has been calved from a glacier is, most of the time, a short one.

Calving is the natural process by which chunks of ice break off from glaciers, ice shelves, or icebergs and fall into the ocean. The forward motion of a glacier makes the end, or terminus, of the glacier unstable, causing ice to break off.

The iceberg that sank the Titanic should not have been there in the first place. It should have died a silent death somewhere in the Arctic Ocean. But, because the Titanic sank in the North Atlantic, rather than the Arctic, means the currents must have taken it far south of where it was calved. Starting on the Greenland coast, it would have moved from Baffin Bay to the Davis Strait and then onto the Labrador Sea and, at last, the Atlantic.

The West Greenland Current (WGC) is a weak cold water current that flows to the north along the west coast of Greenland. The current results from the movement of water flowing around the southernmost point of Greenland caused by the East Greenland Current.

The Labrador Current is a cold current in the North Atlantic Ocean which flows from the Arctic Ocean south along the coast of Labrador and passes around Newfoundland, continuing south along the east coast of Canada near Nova Scotia. Near Nova Scotia, this cold water current

The year 1908 was a warm year that may have triggered the calving in 1911. It may have formed in 1910 or 1911 and could have drifted with the West Greenland Current into Baffin Bay, from where it would have drifted south again thanks to the Labrador Current

Majority of the icebergs melt long before they reach this far south. Only about 1% make their way this far to the North Atlantic. 

On Apr. 14, 1912, the iceberg was some 5,000 miles south of the Arctic Circle, a place where it should never have been. It was about 70 to 80 feet high and about 400 feet long. Its underwater section details are unknown.

According to the British enquiry after the accident, the iceberg was 1500 feet away (about a quarter of a nautical mile or 457 metres) at the time of the sighting. For a ship moving at 22.5 knots (41.7 kilometres per hour), the iceberg would accordingly have been sighted 40 seconds before impact.

After the collision with the iceberg, some measures were put into place to warn ships of ice in a particular area. An International Ice Patrol was formed.

“The International Ice Patrol is an organization with the purpose of monitoring the presence of icebergs in the Atlantic and Arctic oceans and reporting their movements for safety purposes. It is operated by United States Coast Guard but is funded by the 13 nations interested in trans-Atlantic navigation. As of 2011 the governments contributing to the International Ice Patrol include Belgium, Canada, Denmark, Finland, France, Germany, Greece, Italy, Japan, the Netherlands, Norway, Panama, Poland, Spain, Sweden, the United Kingdom, and the United States.

The organization was established in 1914 in response to the sinking of RMS Titanic. The primary mission of the Ice Patrol was to monitor the iceberg danger in the North Atlantic Ocean and provide relevant iceberg warning products to the maritime community”. (Wikipedia)

(More details of the Ice Patrol etc in another chapter).

How strong is an iceberg when compared to steel?

An ice block is hardest towards the centre, gradually losing its hardness moving outward from the centre. At best, it is about 2 to 3% of the strength of steel.

An iceberg’s breaking strength is dependent on the temperature of the iceberg. In the Noth Atlantic, the temperatures were slightly in the negative, making the iceberg weaker than when it was calved much further up north.

It also depends on the speed of the collision - the faster the collision and impact, the stronger the ice. It has been suggested that the force generated on impact could have varied from 500 psi to 3000 psi, which is far lesser than the strength of the steel used on the Titanic.

If the fatal iceberg was indeed about 125 m (410 ft) long, the total height would have been up to 100 m (330 ft). Above the water surface, it would therefore have been 15 to 17 m (49 to 56 ft) high, which would fit the witness statements about the height (above the water surface). The mass would have been 2 megatons.

A ship of weight 52,500 tons travelling at 22 knots, hits an object that weighs 2 million tons.

Structurally weak ice meets strong steel. Logically, the ice should move, break or be damaged. 

But it is the momentum that damages steel. At that speed, at that weight of the ship, it is akin to meeting and crashing against a solid object.

In actuality, the impact was approximately for 9 to 10 seconds, not more. (Calculated from the speed of the ship and the 300 foot damage to the length of the hull).

The momentum was enough to grind off the heads of thousand of rivets,  which would have then popped into the ship, opening up thousands of 1 ½ inch holes. 

The rate of flow through one hole can be calculated to be close to 700 litres / minute.

Which is, roughly, 700 tons / minute total through just a thousand holes.

How many rivets were destroyed will never be known for certain.

6 compartments started flooding.

Along with the ingress of water from the rivet holes and the split hull plates, all that was required for the water to overflow over the supposedly watertight transverse bulkhead, was an angularity of about 12 degrees down by head, with the first (forwardmost) compartment filled to waterline.

After which, one compartment overflows into the next.

With the amount of - suspected initially, later proven through actual deep sea sightings and 3-D scans - that she lasted 2 ½ hours before sinking is actually a tribute to her robust structure and design.

AR