My submarine was deployed for a major exercise involving defence of the coastline. It was a big exercise with a variety of forces operating together. There were multiple ships, submarines, aircraft and helicopters divided into two sides with one side defending the coast and the other assuming the role of the attackers. Clandestine forces were also likely to be used as an asset of the attacking force.
My boat was deployed near the coastline at a choke point to interdict opposing warships entering into our friendly port by simulating attacks. We had already been at sea for many days and were trying our best to avoid fishing boats that operated near the coast. The aim of this exercise was that the attacking force was to attack the shore installations designated as vital points on our coastline using all means available and our task was to defend it to the best of our ability by carrying out simulated attacks in return.
As the game of cat and mouse was in progress, my Radio Room received a message urgently detaching us from the war game. This was a real mission and as submarines are always armed we just slid into our new role. We were ordered to proceed a few hundred miles away towards what appeared to be a bay of about 4 km diameter with a narrow opening. My new task was to identify and take to task a foreign intruder submarine reported to have been seen lurking and taking shelter in that bay. I was told to clear the bay of the intruder submarine.
It is a common practice to encounter intruders from other countries trying to gather intelligence about our major exercise. Foreign navies attempt to deploy aircraft, sometimes ships and most often submarines to operate in the vicinity of any country’s major exercise to gather knowledge about the operating procedures being used. These units try to operate stealthily and spy at the fringes of safe operating perimeters remaining a distance away to avoid close contact. Sometimes, intruder submarines operate in a bolder manner and try to remain close to the action in order to gather acoustic and electromagnetic signatures.
As I silently withdrew from our ongoing encounter with friendly forces and without their explicit knowledge as ‘need to know’ is the principle used for submarine operations, my boat shaped course dived towards our new deployment area. My team assembled in the Combat Information Centre around the periscope was deliberating about the new delicate and dangerous mission that was given to us. We were to locate and flush out the intruder taking shelter in the bay and send him packing on his way away from the assembled large gathering of our friendly forces.
My Navigating Officer also known as the Pilot appeared to be concerned about the constricted sea space in which we were expected to operate. On closer inspection of the marine special chart and the depths in the area, the small bay had a narrow mouth of just a couple of kilometres and which extended into a small space of about 4 km diameter with land surrounding on three sides. Normally submarines operate in open seas and do not go into small constricted spaces. But the mission given to us was to flush the area where an intruder submarine was reportedly sighted by some alert villagers ashore.
Our modus operandi as decided after due deliberations was to enter the mouth of the bay at shallow depth and as soon as we crossed the mouth of the bay we would dive deep into the small bay which was like a bowl in the sea and carryout our search. By the depths shown on the chart, the mouth was constricted with shallow depths but the bay itself had adequate depth for safe operations. As my submarine entered the small bay, firstly we experienced some difference in the trim as the sea water density indicator was showing lesser density. This meant that the waters of this bay were mixed with fresh water either from a rivulet of other underground fresh water source. Grappling with this new phenomenon of submarine control and trying to compensate our weights quickly, our sonar operator started picking up strange sounds of a different type of propulsion that he had never heard before. I was alternating between the Control Room overseeing the trimming as well as donning the headphones offered by the sonar chief to listen in to the strange noise. It was like a strange grinding hissing noise which even I had never heard before during my service till then. It definitely was not the conventional propulsion which submarines have, but more like a hydro-jet propulsion with no propellers.
I had one officer dedicated to only navigation for keeping us within that small cramped area whose sole job was to keep altering our courses and depths so as to avoid hitting the sides of the bay and another officer dedicated to track the strange noise source. It soon became apparent that the other craft was initially just cruising on a steady course. Our entire crew was tense as this being peace time with no specific orders to attack this craft, all we could do was to frighten it to move away from its present hiding place. I then decided that we should make loud noises underwater to make this craft aware of our presence.
Soon, I ordered emptying of one torpedo tube by unloading the torpedo into the compartment and filled the empty launch tube with water. Then we carried out the entire procedure, as if we were firing a torpedo by making all the sounds of relevant actions of flooding the tube with sea water, opening the bow cap as if we were firing a weapon. Simultaneously, we released high pressure air outside which must have made a loud noise. This was done to give the impression to the intruder that another submarine was preparing to attack it with torpedoes. Soon it became apparent that the mysterious craft perhaps having heard our noise and sensing the presence of another submarine in the area started making a beeline towards the mouth of the bay to escape from us. Very soon the strange noise of the intruder submarine disappeared through the gap of the mouth of the bay into the open sea. This encounter lasted about 6 nerve wrecking hours with my entire crew on alert.
Soon my submarine too exited the small bay through its shallow mouth and then we carried out a search in the general area in the open seas. It was apparent that the intruder has decided to abort its mission and had moved out of the area. As my task was accomplished of flushing the area of the intruder, I radioed back to base that my mission was accomplished. I was ordered to return to mother base as our ongoing defence of coastline exercise had just terminated after a fruitful tactical phase.
Unknown to our own friendly forces, my submarine had carried out a very dangerous mission with daring and courage of firstly entering such a constricted area, then we were successful in tracking the strange craft and finally succeeded in driving it out of its lair. To my knowledge, such a mission had never been undertaken before by any submarine of large size in our Navy and this would be a daring example for the younger generation of submariners to emulate in the future. Of course, we would never know the identity of this intruder submarine nor could we make a guess, but that craft had to be small, so as to operate in that confined space supposedly for days. It had some different type of experimental propulsion with which we had no experience. No amount of debrief in harbour with the shore authorities could unfold this mystery.
Life underwater is full of unanswered mysteries and this will remain one of them.
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