In the middle of the North Atlantic, a storm is blowing topside producing level 5 seas. A Russian Krivak steams at 15kts towards its rendezvous point. 10 miles ahead of her a Delta II nuclear submarine prowls, making sure the way is clear.

At the same time, an Improved LA class submarine is heading towards them. Neither side is aware of the others approach.

The engagement started with 30 miles separating the combatants. A combination of her poor passive range and the state of the sea meant the Krivak was essentially traveling blind. Besides, the Delta II was employed to do the detection work if any submarines were in their way. Like all good submariners are taught, the Delta was travelling using passive sonar. Its true she had a better chance of detecting the LA class sub, almost double the chance of the Krivak. But the LA had 2 huge advantages over the Delta II.

One, the old Delta was a noisy boat. And two, the LA’s passive sonar was twice as sensitive than the Delta’s. Combined, this meant the LA could potentially detect the Delta at a range of 23 miles, while the Delta would have to wait until the distance closed to 1.3 miles. The difference in technologies and build dates was that great.

The distance closed reasonably quickly, and the LA picked up a ping on its sonar when the range was just on 15 miles (although using passive sonar, they did not know the distance). The sonar operator had his wits about him and against the odds immediately identified the contact as a Russian Delta.

The LA class was able to keep contact for 3 of the next 4 tactical turns (3 minute turns). At that point, the NATO sub slowed to 8kts while both soviet opposition remained unaware of the enemy stalking them nearby.

When the range between the two submarines closed to 7 miles, the LA class picked up a second contact, and again was able to identify the contact straight away (Krivak).

The Captain of the LA called for a TMA on the Delta and Krivak. It took 9 minutes before a good solution was obtained on the Delta and a fair solution was made on the Krivak. Having a good target solution and not knowing the distances involved either of the contacts, the decision was made to fire 4 torpedos.

2 fast running wire guided torpedoes were fired at the Delta, which at this stage was only 2.3 miles away.

A fast running and a slow running torpedo with no wires was fired at the Krivak, which unknown to the LA class was still 12 miles distant.

The first 2 torpedoes arrived on the Delta almost immediately. Having detected the launch, speed was increased, evasive manovours were taken and acoustic countermeasures released. Incredibly, both torpedoes missed!

The Krivak was unaware of the battle taking place ahead of her or the two torpedoes on her bearing. The fast running torpedo arrived on target …. And missed. A short time later the slow running fish arrived …. And missed as well!

Despite being unseen and having good fire solutions, all 4 torpedoes missed their targets (in game terms, for various reasons each of the 4 torpedoes had a hit probability of 45%. 4 die rolls were made and all were over 45!).

The Delta II did not have a fix on the LA sub and broke off, eventually radioing the danger to the Krivak.

Meanwhile the Improved LA class submarine broke off too, unsure if her position had been pinpointed because of the noisy launch.

The stalk would have to start again from scratch.

Fascinating, go on.

Indeed, great stuff!

Seems to me that the Krivak would now come alive trying to find that LA while boomer does its level best to sneak away.

Took about 2.5 hours of real time to play this out.

 

Krivak's going to have trouble finding the LA i think, with rough seas (sea state: 5). We'll see.

Took about 2.5 hours of real time to play this out. Krivak's going to have trouble finding the LA i think, with rough seas (sea state: 5). We'll see.

 

For sure, but a Krivak is heckuva lot less valuable than a Delta II.

But, by all means, why should a valuable boomer run in front of a FF? The Soviets would never put a boomer to such a risk IMO.

On the other side, this is, now that the LA has failed in its first attempt, a hell of a tactical fight. Keep on telling us.

All 3 units ran blindly fast for a time, putting distance between themselves and the point of contact, and any possible torpedoes launched in their direction. At some point, they all slowed, checked they were not being chased. The hunt for a needle in a haystack started over again.

The weather had not improved, sea state of 5 remained. This was likely good news for the submarines.

It was the Krivak that took up the search first, and most actively. With passive range of only half a mile the Krivak was searching with its active sonar. However the state of the seas (x 0.5) and anechoic coating (x 0.5) meant the LA class submarine would have to be within a mile and a half to even have a chance of being detected. The Krivak was perhaps nothing more than bait.

The LA class was cruising along slowly too, above the layer, taking stock of what its own passive sonar could pick up. Under current conditions the LA class could detect the Krivak beginning at 6 miles. And the Delta at 3 miles.

Skulking below the layer was the Delta. By chance (random die roll for start locations) the Delta was again between the Improved LA class submarine and the Krivak. The Deltas passive sonar had a number of items working against it, and would prove to be remarkably ineffective. A very quiet target, in a noisy sea, on the other side of the layer, combined to give an effective sonar range at most of half a mile.

Perhaps the only benefit the Delta had compared to the Krivak was that at least it would be more difficult to find compared to the surface ship. The game plan was for the LA Class to find and fire on the Krivak, hopefully giving its position away and allowing the Delta an even chance at finding her.

Suddenly, the LA gets a ping! The contact is noted as a submarine of some sort, and immediately a Good TMA is obtained. No shot is taken however, as the submarine has not been positively identified. Unknown to the LA class is that the range is 3.0 miles.

Contact is lost for 9 minutes. When it is regained, the LA determines that it’s a Russian submarine but cannot discern its class. A TMA solution is recalculated and comes back Good! No shot is taken, and unknown to the LA Class the range is now 1.0 mile.

The pattern is repeated at half a mile, however the Delta has a chance of detecting its opposition but fails.

At zero range, the LA class identifies the submarine as the Delta and 2 torpedoes are launched. The Delta fails to detect anything, even the launch of the torpedoes. Launching torpedoes at such close range sends me searching through my rule book.

I was not able to find anything on “minimum ranges”. Because of the vast size of the ocean and any number of rounding variables, while I have the range listed as 0.0 miles, I allow the torpedo to run its course to the Delta assuming the real range is “less than” half a mile. Even so, in writing this down it feels “wrong”. At 0.25 of a mile (400 meters) it seems too short a time for a torpedo to go active and engage an enemy submarine. In the interests of seeking an outcome, two torpedos are fired.

Wires break 20% of the time. T1 = OK. T2 = breaks.

T1 is a 3^rd generation MK48 torpedo against a target that hasn’t heard the noisy launch, as such there are no evasive manoeuvres or countermeasures released, resulting in a 75% chance of the Delta being hit. (Die roll …..) the first Mk 48 torpedo slams into the Delta II. 75 damage points are inflicted. The Delta II is a huge submarine, and rolls with the punch (167 damage points less 75 damage points leaves 92 remaining).

The Delta II has its top speed underwater reduced from 24kts to 18kts. 6 critical hits are recorded. Critical hits come in over the comms “Pressure hull, engineering, engineering, Bridge, engineering and flooding”. The first critical hit is enough to finish off the Delta II. A pressure hull critical hit results in catastrophic flooding and being below the layer, and it is unable to perform an emergency surface and immediately sinks.

A mountain of white water explodes to the surface. The Krivak, some 7 miles away, fails to detect it.

 

The crew aboard the LA class are rocked violently from side to side, the torpedo had only just left its tube, before it seemed to erupt right next to them. The sonar operator is laying on the floor, having fallen from his seat, unable to hear anything due to the ringing in his ears. Disorientated, he points uselessly to his ears to indicate “he cant hear anything”. Across the room, one of the officers working the charts mutters under his breath “man down”. Its unclear if he was referring to the sonar operator, the sinking Delta or a basket that was made against the current president whom had been playing defence with his hands down.

The LA waited pensively in silence, waited for ambient noise to return to normal so they could re-establish their surrounds.

Ping! Contact!, Soviet warship. Good TMA.

(silence), lost him sir!

Ping! Contact! Soviet warship, Krivak class! TMA is good!

Decision time for the Captain: how far away was the Krivak? They’d picked her up twice now, in the last 9 minutes. Was the Krivak as close as the Delta had been? Or more distant? Did he risk active sonar to determine range, with the risk of alerting the Krivak and giving his position at the same time? If he launched did he set the fish for fast speed but shorter range, or slow speed with longer range?

Thinking the options through he realised the contact must be reasonably close, given the condition of the sea topside. 9 minutes had passed since it was first detected, so whatever range there was, was closing.

Launch 2 tubes!

Unknown to the Captain but known to us, range at time of firing was 4 miles.

2 x Mk48 torpedoes speed off into the black. Both trailing wires. 3 minutes later they were just over halfway to their intended target, and a critical time was reached for the Krivak. She failed to detect either incoming torpedo! Forfeiting the chance to jinx or release countermeasures.

Both torpedoes hit home. The Krivak sinks quickly.

 

Observations:

The units in this scenario came about simply because I happened to have there stats with me at the time and it saved digging my data annexs out to come up with new units.

Submarines use passive sonar so that they are harder to detect. But using passive sonar only gives a bearing and an opportunity to classify a target, not a distance. Not knowing the distance can be very disconcerting for the submarine.

The Krivak was using its active sonar. The sea was noisy, the Krivaks passive sonar is next to useless (0.5 mile range), so it made tactical sense (to me) to go active. However both the loud explosion of the Delta and the noisy weapon launch of the final two torpedoes, were more likely to be heard by passive sonar than the active sonar. The Krivak was using the wrong sonar type at the wrong time.

The sea state (level 5) favoured the Improved LA class submarine, which was already at an advantage because of its higher level of specifications. But this still didn’t feel like a walk in the park that the result might indicate on paper.

Next up, I hope to pit a USA Class ship (I chose the Perry in the end) against a state of the art Soviet sub (I have since chose the Akula class. These bad boys look deadly). Which USA class ship should I use? I thought the Perry was more of an anti-submarine ship than say the Kidd class. The Perry is smaller (presumably cheaper), more numerous and its role is probably to screen more valuable ships. But comparing the two, it seems the Kidd is more capable (even if ASW is not its intended role).

Both have 2G towed acoustic counter measures, both are quiet, both have helecopters (which I have tended not to use), so that’s all a wash. But surprising to me, the Kidd has better sonar (4.7nm passive range compared to the Perrys 3.0nm passive range).

Excellent stuff! The noise of the Deltas is why they were kept close to the USSR for better protection from submarines.

Both have 2G towed acoustic counter measures, both are quiet, both have helecopters (which I have tended not to use), so that’s all a wash. But surprising to me, the Kidd has better sonar (4.7nm passive range compared to the Perrys 3.0nm passive range).

Perry has a smaller hull and a smaller sonar dome than Spruance. The Perry are clearly cheaper, multi-task but more air defence oriented (Standard missiles and not ASROC) and probably designed to operate in group with other warships (as convoy escorts) detecting incoming subs at long range with the towed array and sinking them with the Seahawk at long range, The rare Kidd were developed as air defence variants of Spruance for Iran and not delivered after the facts of the 1979 Islamic Revolution. Perhaps for a single ship vs sub you should use one of the Spruance variants.

Yeah, good point about the Spruance. I dont have any knowledge on units roles or tactics, except for whats in the Data Annexs. So advice or background on units is good.