Titan Submersible - The Mechanical Engineer

Titan Submersible Tragedy

As we are aware of a tragic accident i.e. failure of the Titan submersible which went for touring the RMS Titanic on Sunday 18th June. The Titanic drowned in the North Atlantic Ocean on 15th April 1912. Currently, the wreck of Titanic is lying on the sea bed which is 3.81 km deep from the sea surface. The exact location of the Titanic can be viewed in the following figure.

Titanic Wreck Location

word image 3561 1 — ***Figure 1: Titanic Ship Wreck Location***

word image 3561 2 — ***Figure 2: Titanic Ship on the Sea Floor***

Difference between Submersible and Submarine

Submersible	Submarine
It is relatively smaller in size. Almost in the size of a minivan. Length is up to around 6 to 7 metres.	Relatively bigger. The length of the submarine is in the range of 170 metres.
It is used for marine exploration and deep-sea research.	It is used for military operations.
It needs a mother ship to get launched.	It can leave the port and come back by itself.
Needs oxygen supply tanks.	Can generate its own oxygen.
It can be operated remotely.	The crew is a must to operate the submarine.

Table-1: Difference between Submersible and submarine

How does Titan work?

Titan is a submersible type underwater rover. Generally, launches from the mothership. It has four electric thrusters for manoeuvring as shown in the following figure. OceanGate is the private firm that provided the Titan submersible for the Titanic exploration on Sunday, 18th June. Titan was launched from a mothership typically an icebreaker. Titan has the capacity of 5 people 4+1, 4 passengers and 1 pilot. Steering is controlled by a joystick. At the tail portion, it houses critical equipment like an oxygen generator and navigation system. Etc. Titan has 96 hours of oxygen backup. The nose portion is made of Titanium metal. Titan is equipped with headlights and a camera. At the seabed, visibility is zero. Sunlight cannot be penetrated at the seabed. The hatch can be opened only from the outside. It has a viewport at its nose. Overall, Titan is the size of a minivan. It has an inbuilt toilet as well located in near the hatch portion.

Trip Plan

As per the schedule, Titan requires 2 hrs to reach RMS Titanic and 4 hrs touring the Titanic and another 2 hrs to reach the mothership at the surface, in total the estimated time for the Titanic trip from the sea surface is 8 hrs.

What happened to Titan Submersible?

The following represents the detailed timeline of what happened to the Titan submersible.

Sunday 18th June 08:00 hrs

The descent of Titan begins from the mothership located at the sea surface.
96 hrs count down begun. (Countdown is based on the limited oxygen supply)

Sunday 18th June 09: 45 hrs

The communication between the Titan submersible and the Mothership was lost.

Sunday 18 the June 17:40 hrs

The sub should return to the mothership by 16:00 hrs as per the trip plan.
Coastguards were notified regarding the missing sub.

Monday 19th June

USA and Canadian rescue operations were initiated. Sonar buoys were dropped in the water to detect the acoustic signal.

Tuesday 20th June

Banging noises were detected by Canadian aircraft. It indicates that the passengers would have tried to communicate with the mothership by banging the walls of the hull. So that the acoustic signal will be captured by the sonar sensor.

Wednesday 21st June

The US deployed Remote Operated Vehicle (ROV) for the rescue operation

Thursday 22nd June

96-hour Oxygen window closes.

Observations on the Seabed

Remotely Operated Vehicle (ROV) under the water identified the Titan wreck on the sea bed approximately 1600 feet from the bow of the RMS Titanic.

Pressure on the Titan sub near the sea bed

From the basic hydrostatic principle, the pressure exerted by the fluid on the immersed body at rest is given by

$P= \rho g h \,$

Where $\rho \,$ represents the density of the fluid in which the body is immersed. The density of seawater is $1036 \frac{kg}{m^3}$ .

g represents the acceleration due to gravity i.e. $9.81 \frac{m}{s^2}$

h represents the vertical distance from the free surface of fluid to the centre of the immersed body in the fluid.

The vertical distance between the free surface of seawater and the RMS Titanic is around 3810 m. The pressure exerted on the Titan sub by the seawater at the sea bed can be calculated by using the above equation.

The pressure is around $38721639.6 \, pascal \, or 394.8 \frac{kg}{cm_2} \,$

Assume the body surface area of a 70 kg adult is $17300 cm^2 \,$ . The pressure $394.8 \frac{kg}{cm_2} \,$ is equivalent to 6830 metric tons of weight acting on the complete human body. It is equivalent to 3880 SUVs on the human body. And also it is equivalent to half the weight of the Eiffel Tower on the human body.

Why Titan submersible is imploded?

One of the possible reasons is that any small flaw in the structure of the hull or bolted/welded joints is enough to create catastrophic failure of Titan sub under the pressure $394.8 \frac{kg}{cm^2}$ . It is suspected that Titan sub would have undergone instant implosion i.e., complete crush.

Safety Features of Titan Sub

Lead pipes, sandbags. Etc attached to the sub will drop off after a certain amount of time and makes the Titan return to the sea surface (based on the buoyancy principle) even though everyone in the sub is unconscious. But the flaw in the structure of the hull dominates the above-mentioned safety features.

Facts about Titan sub

The cost of each ticket is $250,000.
Titan submersible pilot’s wife is a descendant of the couple who died on Titanic.

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