FIRST HAND | How Shrimp Nearly Wrecked India’s First Brush With A Nuke Sub

By Vice Admiral (Retd) R.N. Ganesh

As always, the submarine left harbour in the small hours, while the city slept. A huge, ominous shadow in the dark, she moved silently but for the faint hiss of the water against her sides. At five thousand tons, she was the largest warship in the Indian Navy after the carriers. The young Captain on the bridge had done this  dozens of times, but taking this formidable vessel out through the narrow channel was still exciting, with a potential surprise lurking at every bend.

Vice Adm R.N. Ganesh

Slowly the submarine made its way out of the harbour and set course for the diving area. Today they were leaving on an extended surveillance patrol of the Bay islands under simulated war conditions, as part of the essential and never-ending process of maintaining presence in one’s own waters.

Before that, however, there was a game to be played. Units of the Fleet were returning from deployment in the south, and Headquarters had decided that the submarine would intercept them in a staged encounter and carry out a mock attack before detaching to proceed on her main mission. The ships would be closer in to  the shore and the submarine further out, listening out for them against the backdrop of shallow water noises. The interception area was some miles to seaward of an estuary, and recent rains would have made the seawater density variable, causing trimming problems. Not ideal waters for a large nuke, thought the Captain, but therein lay the challenge. In addition, his crew would enjoy the thrill of the hunt.

“Bridge – twenty minutes to diving area!” came the report from the charthouse. “Right – inform the Commander, please”. The order was still being relayed when the Captain reached the control room, just as the Commander ordered “diving stations.” The Engineer Officer was already there.

“We’ll catch a quick trim, then we need to crack on some speed; our initial position is about twenty miles south of here.” The first dive after leaving harbour was always a ‘trim’ dive – a slow, deliberate dive done in stages to make any adjustments necessary to the Engineer Officer’s calculated trim.

“Diving stations correct, sir,” reported the Commander. The Captain nodded at the Engineer Officer. They had worked together as a close-knit team for a year now, and there was no need for unnecessary words.  Flood end groups” ordered the Engineer Officer. The diving panel operator switched the end group ballast tank main vents to “open”. There was a muffled roar as hundreds of tons of seawater flooded the end groups of tanks. The submarine sank perceptibly beneath their feet; she now rode on the buoyancy of the centre group tanks alone. While the Commander ordered “Inspect compartments” and received the reports from them, the Captain studied the trim and depth gauges and the inclinometer, looking for the first pointers to any major problems in the trim. There were none. “Submarine inspected and correct – ready to go down.” reported the Commander. “Permission to flood the centre group, sir” asked the Engineer Officer This time the roar of the water flooding the tanks was louder since the tanks were around the hull right  outside the control room.

“Trim her at 40 meters for four knots – we’ll be doing a lot of listening.” The Engineer Officer nodded. The trimming operation was over soon, and as planned, they increased speed to fifteen knots. It felt good to be able to order higher speeds and not worry about the battery, thought the Captain. “We may expect contact with the ‘enemy’ between an hour and two hours from now,” reported the NO. The Captain left the control room leaving instructions to carry out a sonar search of the area and call him when anything was heard.

They reached their designated position twenty minutes early. An hour passed, and then there was a knock at

his cabin door. It was the Sonar Officer. “There’s a small problem, sir”, he said; Pilot says they should be within twenty miles of us to the south, but the sonar is unable to hear anything.”

“Unable to hear?” repeated the Captain.

“The entire southern sector – that’s where NO says they’ll probably come from – is blanked with noise. We

can’t hear anything through it.”

This was bad news. If the sonar malfunctioned, it could take hours to locate and rectify the fault. Even the main mission could be in jeopardy if dockyard help became necessary. “Get the Commander and the electrical Officer to the charthouse. We need to discuss this. Who’s on the sonar?”

“Master Chief Attar, sir” was the answer. The Captain was reassured. Attar was the best sonar Chief in the submarine arm, as far as he was concerned. He went across to the ‘sound room’, which was just abaft the control room. The Sonar Chief wished him ‘Jai Hind”, and silently handed him the headphones. The Captain had spent many an hour in the sound room getting his ears tuned to the sounds of ships’ propellers – called ‘hydrophone effect’ or ‘HE’ for short. On this occasion all he heard was the noise – it was a continuous crackling, with an occasional popping sound as made by a fire of dry, resinous wood. The noise blanked the entire southern sector – it would be impossible to hear anything through that racket, even if the ships passed close by.

They held a council in the charthouse. “No problems during the pre-patrol checks yesterday?” asked the Captain, though he knew that all sensors had been reported checked and correct. The Electrical Officer

confirmed this.

“Can you say whether the noise is external or a system fault?”

“I would say external” interposed the Commander. We made two ninety-degree turns after initially hearing the noise, but the true bearing of sector didn’t change.” The Captain nodded in agreement.

Time was ticking away. The submarine would never live it down if the fleet ships sailed past undetected. Many years earlier, the Fleet Commander, a bluff, laconic man with a sardonic sense of humour, had been the Captain’s Divisional Officer in Kharakvasla. He would have a thing or two to say about the marvellous capabilities of nuclear submarines when they next met, thought the Captain wryly.

He went back to the sound room. The Chief Sonar operator handed him the headphones and said with conviction: “It’s bio-noise, sir.” The Captain agreed. Landsmen, he mused, thought of the ocean depths as dark and silent. In fact, there was a cacophony of noise down there that could drive submarine sonarmen to distraction – whales with their long, soulful moans, dolphins with their clicking and whistling, and a host of other noisy creatures, not to mention the ambient noise of the sea itself. They had a whole taped reel of

these sounds but he had never heard this kind of noise before – certainly never anything near this loudness.

“Can’t we go around” asked the Sonar Officer.

“No – we can’t leave the area. Maybe the noise will stop after some time.”

“Sir….” The Sonar Chief hesitated. “We can try one high power transmission in that sector. It may have some effect.”

“Good idea!” The Captain got up, slapped the Sonar Chief on the shoulder, and left for the control room, visibly excited.

Although the submarine had a powerful active sonar, a transmission could compromise its stealth and was only used after carefully weighing the balance of tactical advantage. However, on this occasion there was nothing to lose. And if it worked it was well worth the tactical ‘risk’.

Soon the order came from the control room. “Sound Room, Control – standby single pulse, high power, centre bearing 200.”

“Sound room roger, stand by single pulse, high power, centre bearing 200.”

The Captain went back to the sound room, the Electrical Officer close on his heels. ‘Let’s hear it, Master Sa’ab”. One of the sonarmen switched on the loudspeaker for them. The noise was as loud as before.  Sound room ready for single pulse, high power, centre bearing 200” reported the Sonar Chief. “Transmit” came the order. The second operator flipped up the guard cover and pressed the red button. They could hear the pulse as it left the ship.

More than a minute passed. And suddenly it was as if somebody had turned off a switch. One moment there was that overpowering crackling noise, and the next – total silence. The Captain shook the Sonar Chief’s hand and said “Well done, Master Sa’ab!”, and went back to the control room. Hardly had he sat in his

Captain’s chair that the report came in, the deliberately expressionless voice of the Sonar Chief:

“Control room – group HE on bearing 175, classified warships.”

The atmosphere in the control room was electrified. The Commander took the mike in hand: “D’ye hear there! This is the Commander. The sonar team has detected ‘enemy’ ships in sector south. A big shabash to them. Action stations – torpedo attack!”

“Game on!” said the navigator, as he bent over the attack plot.

We never pumped our fists in those days.

Post Script: This story is based on a real experience in INS Chakra in 1988. The noise was generated by the denizens of large shrimp beds in the general area of Kakinada. From later reading I learned that the culprit was the snapping shrimp, which thrives in tropical waters near the coast. A one and a half-inch crustacean almost foiled a 5000-ton nuclear submarine!

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