OK, i've placed a soviet Akula class submarine in front of a USA "fleet". I've given the fleet 4 layers if you like, and i'm ignoring air support at this stage. Can the Akula penetrate the layers and get a shot off at the Nimitz???

 

1st layer is the picket, where our Akula has to try and stealth past a Perry class warship. She is a small and quiet ship but will be running at speed ahead of our fleet. While the Perry can carry a Sea Hawk helecopter, it wont be in this encounter.

 

2nd layer is Arleigh Burke, i believed the AB is a good ASW type of ship. But looking at her sonar stats she is not much different to the Perry class. Oh well.

 

3rd layer is Bunker Hill cruiser. Her sonar gear is better than the first or second layers.

 

4th layer, the big prize (should he make it this far) is the Nimitz.

 

My plan for the Akula is to quietly cruise past each layer until she can line up a shot on the Nimitz. Even if she cant sink her, politically it would be a winner, and the USA would have itself an embarrasing bloody nose. To give the Akula a fighting chance i have placed her in front of the fleet. After this encounter, i will try the same thing with her behind the fleet so she has to run at speed and penetrate the defensive layers to see what effect that has. Interestingly the Akulas submerged speed is faster than any of these ships surface speeds.

 

I toyed with the idea of having a roaming LA class sub for the Akula to deal with but this is already the biggest encounter i have put together in my short H4.1 life. So i chose to leave it out.

 

Anyway ... i have a picket to overcome ...

Hey KC,

 

Buried in the following thread, Amur vs Perry and Burke, was a solo attempt at getting past a screening Perry to get at a Burke conducting maritime inspections.

 

I guess that my first questions/observations are what is the size of the "playing" area. What is the general situation, has war broken out, are tensions high, is the US force actively searching for subs? Are the opposing forces on a converging course?

 

In my example I randomized the patrolling Perry's course, and despite that it was in relatively restricted waters, the Amur SS was able to slip past undetected.

 

Also in some of my older LCS scenarios I found that diesel subs, in this case a Kilo, could essentially do whatever it wanted provided it was not very, very close to, or under, its passively searching opponents. LCS Subs Thoughts The drawback for the Kilo was its relative slowness while submerged, and therefore it unability to get where it could influence the "battle". LCS a stroll through dangerous waters

 

Who knows for sure.

Somewhere in the greenland-iceland-UK gap. For whatever the reason, NATO and Russian have the safeties off.

 

For ease of the game, I have placed a Perry class, then an Arligh Burke, Bunker Hill cruiser and then the Nimitz all in a straight line ahead of the Akula. In effect, the Akula will drive (swim?) straight underneath each vessel intil it gets into the inner ring. This just helps me with keeping track of vessels as I learn the H4.1 rules.

 

The Russian Akula cruises along at (random D10 roll for speed) 6kts. Depth is intermediate II. 7.0nm out is a Perry class ship, which forms the Picket. She is steaming along at 20kts, normal ocean speed movement. Sea state (random roll) is 5.

 

The Akula was able to check for detection against the Perry straight away, and it took a couple of tactical turns before she was picked up. The Akula was eventually able to classify the Perry as a “US Ship”. And since the fleet was expected to be in the area, the Akula assumed this was part of the picket.

 

The Perry on the other hand was essentially blind to the Akula, needing to be within a mile to have any chance of picking her up even using active sonar. This was mainly due to the Perrys speed working against her.

 

I immediately thought this same problem is going to affect the other ships as well (similar sonar characteristics and ship speeds). So when the sub gets within sonar range of a ship and we start using tactical turns, in the plotting phase I will roll D6 and on a roll of “1” I will have the ship slow to 5kts to simulate it doing sprint/slow type searches. I will plot the akulas movement before the roll, so I don’t know the outcome beforehand. This should give the ships a better chance of detecting the sub.

 

I got a few of the rules wrong during this little encounter, and decided since the Perry failed to pick up the Soviet Sub I would move on to the next line in the Nimitz defence. There was little to no point in the Akula firing on the Perry. It’s a small and relatively unimportant ship. If bigger game is detected next time, I might fire on them if only to run me through the target detection, classification and firing torpedoes sequence. You cant get enough practice at this!

 

In future I will roll a D10 and half it. This will represent the closest the Sub will pass to a ship. For example if a 5 is rolled, instead of the Akula having to go directly underneath a ship, she will approach the ship and then when the distance gets to 2.5nm, she will start to pull away out the other side. This simulates the ships moving in the open sea and passing each other, but never being side by side (like on a highway).

 

Thoughts so far

Ships have to be very close (and moving slowly or in slight seas) to detect a sub. When I play through this scenario again, having the sub chase down the fleet (but having to negotiate the same obstacles) will be much different. Because the sub will be easier to pick up and the Akula will have a hard time hearing anything itself I suspect.

 

I need a better way of simulating ships on the high seas rather than having the linear examples I have used so far. How are other people moving ships around? I hope to keep things to pen and paper. How are others determining random ship movement???

 

I had a quick look at Helicopters, and they would detect subs by dropping sonar buoys. My quick scan of the rules shows that is a hard way to initially pick up a sub also.

 

I needed to remind myself that sonar only gives direction, not distance when it detects a contact. So the sub doesn’t know (until the ship passes overhead) how close they are until the direction of contact changes (from 90 degrees to 270 for instance). I wonder if 2 subs detecting the same contact could work out distance (triangulation?). Maybe they couldn’t, since subs are not normally in sub to sub contact to share info …?

 

Is it realistic for a sub to surface and use its periscope to check for distance to a contact? And confirm contact type? Maybe I should have a sub try this next time to see what happens.

 

I will point people to 6.5.2.2 in H4.1. It might answer a thread question re when to arm torpedoes because you don’t know how far away a contact is if your just using sonar (you know direction but distance to contact). Here it says a player must log torpedo course, depth and enable point. The question is “how do you set your enable point?”. Well, it says in this paragraph that if the torpedo acquires its target passively, it automatically switches to active and homes in. Does this raise another question though? Do you need to be rolling for the passive torpedo to detect a target, and if it picks it up then it goes active and homes in? A table at the bottom of page 6-28 gives some info re types of torpedoes and some stats.

 

 

 

Second line of Defence

 

The Arligh Burke has been made aware a Russian submarine is operating in the area. As such, she is being much more careful that the Perry. On a roll or “1 or 2” in the plotting phase of the tactical turn, she slows to 5kts. In each next plotting phase, she will speed up to 20kts on a roll of 1-3.

 

The Akula is moving at intermediate depth II at (random D20 this time to also even things up) and a 19 is rolled, so its 19kts.

 

The Akula forges through the water at 19kts. The AB is at a similar 20kts. If nothing changes the Akula has a chance to detect the AB beginning at 5.1nm.

 

Tactical turn1

Range 7.0nm. Akula intermeadiate II and 19kts. AB at 20kts. Units will pass at (D10 = 5 / 2 = 2.5nm before distance starts to extend). Due to the combined closing speed, the distance closes to 5.1nm, right on the edge of the Akula being able to detect. Die roll is 59 > 25 therefore no detection.

 

Tactical turn 2

Range is 5.1nm. Akula maintains 19kts and AB (D6 roll is a 2!) slows to 5kts. Now it gets interesting. After the movement phase the distance is 4.0nm. Using passive sonar the AB could start to detect at 3.9nm, so she just misses out on a detection roll. The Akula could start to detect the AB at 1.9nm so she doesn’t get a chance to detect either.

 

Tactical turn 3

Range 4.0nm. AB rolls D6 in plotting phase and gets a 5, so she stays at 5kts. After movement phase the distance is 2.8nm. The AB has a 50% chance of detecting the Akula and rolls 33, we have a contact! Classification is not possible (cross reference very quiet contact with LF-MF sonar type on page 4-11). Hmm, so it could be a whale?

 

The Akula is not within sonar detection range and so keeps same course and speed.

 

Tactical turn 4

Akula maintains 19kts. AB is searching at 5kts.

 

Start range is 2.8 with closing speed of 1.2nm. So after moving 0.3nm they “pass” at 2.5nm and range starts to extend again to 3.4nm.

 

AB has a 50% chance to maintain the sub, plus 15% so needs 65 or less and rolls 79. The Burke has lost contact!

Tactical turn 5.

Starting range is 3.4nm.

 

The Arligh Burke was alert for a sub and had an unclassified contact, so she maintains 5kts and continues to search. Instead of moving ships around etc … I decided there is a 50% chance of the burke turning onto a course to intercept the unknown contact, and she rolled a 95. I ruled the Burke failed to move in the direction of the Akula.

 

The Akula continued on at 19kts and moved 0.95nm. I rolled D100 again and got 93, so 93% of 0.95nm = 0.88nm moved away (this is me gaming the Akula being able to move 93% of its movement away from the Burke rather than plotting movement). New range is 4.3nm.

 

Tactical turn 6

Starting range is 4.3nm.

 

Random D100 roll for Burkes heading towards unknown Akula is … 87. Combined speed of units is 1.1nm apart x 87% is 0.96 + 4.3 = 5.3 nm.

 

Detection phase and the AB has a 25% chance +15% to regain contact for a total of 40%, she rolls a 95 (really? This is my random die roller results in an excel spreadsheet? 79, 95, 86 and 95. Theres some pretty high rolls. Any more results like this and NATO can claim to be diced in this one).

 

The AB is out of the Akulas sonar range so no chance to detect.

 

Tactical turn 7

Starting range is 5.3.

And its just occurred to me that on a roll of 01 and the Burke should move closer to the Akula, and on 100 the distance should climb. On a roll of 50 maybe the distance stays the same? Something to try.

 

Random movement generator (I just made this name and concept up) is 79. Its 29 higher than 50 so combined speed of 1.1nm x 1.29 = 1.4 + starting range of 5.3 gives a new range distance of 6.7nm. Neither side is within contact range.

 

Tactical turn 8

Opening range is 6.7nm.

 

Random movement generator is … 30. So the gap will close. 1.1nm * .8 = 0.88 to be taken off 6.7 = 5.8nm is the new range.

 

The AB gets another chance to regain contact (rule 4.4.3 this is the 4th and last time the Burke qualifies for the 15% to maintain contact).

So its 25% + 15% for a 40% chance and the roll is 35 – contact is regained! The Burke has a new direction to the contact (but will never be able to classify it. How can the Burke ever classify the sub and therefore fire on it?

 

Enough for today.

The AB gets another chance to regain contact (rule 4.4.3 this is the 4th and last time the Burke qualifies for the 15% to maintain contact).

So its 25% + 15% for a 40% chance and the roll is 35 – contact is regained! The Burke has a new direction to the contact (but will never be able to classify it. How can the Burke ever classify the sub and therefore fire on it?

 

Enough for today.

 

I think a Perry at a greater distance than this would be able to classify an Akula, Perry's have great towed arrays! Also, you don't NEED to classify it. Intel would tell you if you had friendly sub in the water. Shoot a fish down his bearing, watch him turn and run. )

 

I really enjoy these paper rules AARs.

I'm not certain if it is an optional rule as I do not have my rules in front of me at the moment, but something to consider is when employing passive towed arrays there can be ambiguous detections, and additional steps need to be taken to determine to which side of the array the contact is being detected.

 

I'll double check later.

I'm not certain if it is an optional rule as I do not have my rules in front of me at the moment, but something to consider is when employing passive towed arrays there can be ambiguous detections, and additional steps need to be taken to determine to which side of the array the contact is being detected.

 

I'll double check later.

 

It is 4.4.2.4 Bearing Ambiguity and Towed Array Stabilization (Optional Rule)

 

Also of note, the Akula being at Intermediate II depth puts it below the Layer/Thermocline. See 4.4.4.1, but essentially if the layer is between the sonar and the target, whether active or passive, the sonar range is halved. There is an exception when the scenario sea state is 5 or higher, the roughness of the seas prevent the layer from forming.

I'm not certain if it is an optional rule as I do not have my rules in front of me at the moment, but something to consider is when employing passive towed arrays there can be ambiguous detections, and additional steps need to be taken to determine to which side of the array the contact is being detected.

 

I'll double check later.

 

It is 4.4.2.4 Bearing Ambiguity and Towed Array Stabilization (Optional Rule)

 

Also of note, the Akula being at Intermediate II depth puts it below the Layer/Thermocline. See 4.4.4.1, but essentially if the layer is between the sonar and the target, whether active or passive, the sonar range is halved. There is an exception when the scenario sea state is 5 or higher, the roughness of the seas prevent the layer from forming.

 

Bearing Ambiguity only requires a turn (of the array) to eliminate...once the false bearing will develop a very high line of sight rate. I don't know how the rules deal with it.

I'm not certain if it is an optional rule as I do not have my rules in front of me at the moment, but something to consider is when employing passive towed arrays there can be ambiguous detections, and additional steps need to be taken to determine to which side of the array the contact is being detected.

 

I'll double check later.

 

It is 4.4.2.4 Bearing Ambiguity and Towed Array Stabilization (Optional Rule)

 

Also of note, the Akula being at Intermediate II depth puts it below the Layer/Thermocline. See 4.4.4.1, but essentially if the layer is between the sonar and the target, whether active or passive, the sonar range is halved. There is an exception when the scenario sea state is 5 or higher, the roughness of the seas prevent the layer from forming.

 

Bearing Ambiguity only requires a turn (of the array) to eliminate...once the false bearing will develop a very high line of sight rate. I don't know how the rules deal with it.

 

From 4.4.2.4. A course change of 45-135 degrees port or starboard, then restabilization of the towed array which is dependent upon sonar platform's speed and whether considered a long or short length of the array, and then passively re-acquiring the target.

 

Time in Tactical Turns

Speed (kts) 5 10 15+

Short Array 2 1 1

Long Array 3 2 1

Where in the rules does it tell you how fast (or slow) you need to be going to be able to use a fast or slow towed array? I have read about the differences, but i havent seen anything that says what the speed cut off is. Is it a hard and fast speed given, or a % of a crafts top speed?

 

4.4.2.3 talks about towed arrays. And low or high speed. It also talks about 15, 25 and 30kt limits applying to towed arrays but gives no distinction between fast and slow.

It's probably worth me pointing out I don't actually have Harpoon 4 (don't want anybody thinking I couldn't be bothered to lookup the rule) .

 

Looks like fun though. I'll certainly get it if I can find it at a reasonable price.

Where in the rules does it tell you how fast (or slow) you need to be going to be able to use a fast or slow towed array? I have read about the differences, but i havent seen anything that says what the speed cut off is. Is it a hard and fast speed given, or a % of a crafts top speed?

 

4.4.2.3 talks about towed arrays. And low or high speed. It also talks about 15, 25 and 30kt limits applying to towed arrays but gives no distinction between fast and slow.

 

Slow/High Speed Towed Arrays are declared in the remarks column of Annex M1 Sonar Systems. The effects of Slow/High Towed Array Sonar and the applicable speeds are found on Page 4-11, in “Own Ship Sonar Speed Modifiers”.

 

Hope that helps

I think a Perry at a greater distance than this would be able to classify an Akula, Perry's have great towed arrays!

 

I really enjoy these paper rules AARs.

 

Yeah, I dont know anything about the equipment, but the Perry has a MF-LF sonar and according to the rules it cannot classify very quiet contacts. Not sure if anyone else wants to chime in.

 

Glad you like the write ups. Just doing what i can.

Yeah, I dont know anything about the equipment, but the Perry has a MF-LF sonar and according to the rules it cannot classify very quiet contacts. Not sure if anyone else wants to chime in.

 

The Perry's hull mounted SQS-56 is a medium frequency (MF) set, so yes, it would fall into the "not capable of classification" category in the Base Classification Probability (Pc) table on page 4-11.

 

The Perry's SQR-19 towed array, however, is a VLF-LF (very low frequency/low frequency) set, so it gets the 10% modifier for Pc.