RA - Can a Sierra II defeat a 688?

[Kapitan]

Mission report 688 V Sierra II using RA 1.53

This is what I have found note that I couldn’t play your mission you uploaded as it says it’s a 688 file (File is .mss should be .mu), so what I did was create my own scenario, set to war time and on the nav map placed a circle 20nm in diameter.
I then set the 688 and me to several dynamic locations so we shouldn’t show up in the same place all the time, I did a few dummy runs with show truth on to make sure dynamic location was working.

This mission was a pretty long one it took me 4 hours and 30 minuets most of which was spent on the sonar, and at the kettle making cups of tea.

This is the mission set up

Both 688 and Sierra II start at 250ft or 76m at 5 knots Ladder box patrol set up, 688 has his towed array deployed, the weather is clear sea state 3 bottom type is rock and there’s a convergence zone.

Sierra II Load out

Tube Number (1) USET 80 (2) USET 80 (3) TEST 71M (4) TEST 71M (5) SS-N-15 (6) Korund
Stores: (5) TEST 71M (3) SS-N-15 (5) USET 80 (8) Korund (0) PMT-1 (0) Skhval
Counter measures: Tubed: 1 Active 1 Passive Reloads: (17) Active (8) Passive

Notes: TEST 71M max depth 400m USET 80 max depth 1000m

Navigation notes: I have used both the 3 minuet and 6 minuet rules in this scenario if your not aware of what they are here is what they are

3 min rule: Speed x 100 = Yards travelled in 3 mins (multiply by 20 for the hour)
6 min rule: Speed / 10 = Miles travelled in 6 mins (you can multiply this by 10 for the hour)

Deck Log

1200 Enter into the game submarine is at 5 knots 76meters course 000
1201 Extended towed array noted layer is at 142m
1203 Reset all torpedo settings from default range set at 1500yrds speed 35knots ceiling 2m & max
1251 New contact detected changed course 270 contact started to vanish
1253 Course correction 290
1259 Contact lost changed course 320
1302 New course 000 to sweep Contact regained
1313 Turned to 060 to resolve ambiguity
1324 Turned again to 220 to resolve ambiguity
1333 Contact confirmed as own ship
1349 Dived to 500m



Reasons for my manoeuvres and settings: The settings on the weapons are such that the minimum safe distance from submarine is set 1500m I don’t want the torpedo arming too far out as the enemy boat maybe closer, also the ceiling is set to 2m and the torpedo maximum depth to give the weapon its full range.
The course changes are to confirm I have a ghost and correct track via the TA as I don’t have a hull contact, notice though I didn’t leave enough time to let the towed array go straight this is a mistake!
I kept turning to ID the track and should have let the TA straighten out I may have concluded quicker I was tracking my own ship, so here I have wasted about 40/45 minutes in tracking myself.

I have dived to well below the layer here 500m this will enable me to sprint and drift, although I do want some power to keep going forward hence why I return to 5 knots, the sub effectively drifts from 20knots to 5 knots which is enough in this instance.


1359 Increased speed 20 knots
1415 Decreased speed 5 knots
1528 Course change 340
1540 Increased speed 15 knots

Reasons for my manoeuvres: Right now at this point I have no contacts, so at this point I am projecting where he maybe, knowing that he is in the circle somewhere I decide to head towards the centre of the circle.
I have changed course to 340 and left 12 minutes to allow the towed array to go straight and see if any new contacts are out there, when satisfied there’s none I speed up to 15 knots, to sprint and drift for 6 minutes.

1546 Decreased speed 5 knots
1551 New contact
1552 Course change 300 to resolve Towed array ambiguity
1555 Ascending to 180 meters ambiguity resolved classified 688
1659 Decreased speed to 2 knots
1614 Increased speed 5 knots
1624 Ascending to 70m
1625 Decrease speed 4 knots



Reasons for my manoeuvres: After decreasing I go on the hunt again, and find a new contact, this time the hull and towed array are seeing the same contact so I turn to get a Master contact.
I initially ascend to 180 meters and set speed 2 knots as I don’t want to spook the contact.
Once I have a firm handle on the narrow band 50hz I increase to 5 knots and decrease depth to 70m this is to pop up above the layer.
I slow to 4 knots by mistake I could have stayed at 5 knots, however popping up you can go slower to 1knot this is almost the same as sprint and drift, it will make it harder for him to see you crossed the layer.

1626 HF Sonar detects object at bearing 277 sets HF Sonar mark on nav map visual confirm estimate target 2-3nm tracking left to right
1627 Tube 1 readied and fired USET 80
1628 Loud explosion bearing 288 close aboard 700 yards
1630 Mission end



Reasons for my manoeuvres: I have a slight hunch the enemy boat is fairly close my estimation put him 2-3nm from me so I figured I would have a look at the forward looking HF Sonar, this is me just trying to visualise the enemy and if I can see a blip and I do

I watch the HF sonar for a minuet and I know he is tracking left to right on my bow, the HF Sonar has put a mark on my nav map so I go to the weapons station and set my torpedo to go active at 500m, the reason I have done this is because 1. I want to see a reaction 2. He is close in and I don’t want to chance my guess too much.

I have selected tube 1 USET 80 in active mode, I know he has the MK48 ADCAP and at this range I don’t want to give him a chance to shoot back too quickly, for at least 60-90 seconds he will be trying to figure out what’s coming his way so that’s my window and I ready the Korund for firing. Down the same track as the torpedo.

Just before I fire, I am readying to dive to 500m and speed up to 25 knots and make a turn to 210 this will enable me to try and get outside his torpedo cone, at this point I’m also readying my countermeasures and preparing to reload and make another turn back to 300 once at depth.

I am also thinking he will make a turn to around 290 and speed up to get out of my torpedo cone, and he will likely dive below the layer, at this point I am almost lined up for a second shot if he does do this.
This is what some would call 3rd stage thinking as I’m trying to anticipate the next 2 moves the torpedo he will fire at me will make, and also the moves he is likely to make.

What I didn’t anticipate was that he was much closer than I thought being at a range of about 700 yards, this is where my prior planning for setting the weapon with a shorter enable range paid off.
But what I did notice was as soon as I fired he did seem to speed up and was turning, I noticed this on the HF sonar.

Edited note: I also draw out my course changes on paper so I don't have to keep switching to the nav map all the time, it looks like this, the red ink is enemy and you can see i note my bearing changes 1cm is roughly 1nm, its not accurate it just helps to keep me in some sort of picture to show me my own track.
The smaller drawing is my track and fire points the green box is my aim point the red line is the current enemy sub track. each dash line is roughly 0.5 nm hence my estimate of 2-3nm

Conclusion

So over all here is the big take away, notice in the earlier part of the mission I majorly screwed up by wasting time tracking myself, this is a schoolboy error on my part and I should have known better.
Sometimes simply projecting where the enemy maybe can work out and it did in this case, it doesn’t always go that way I simply in this instance got lucky.

I did watch the replay and he started off around 16 maybe 18nm away from me to the North West (I started in the South East corner of the circle again dynamic location was on my boat too). so, my theory of head for the centre in this case was correct. Don’t forget I did set multiple dynamic locations for this mission in various spots across the map.

On watching the replay, he initially started heading east, then turned south and spent a considerable time heading south too at least an hour, during this time I was screwing myself over tracking my own ship, but effectively we closed the gap between us during this time.

He turned west for about 8 minutes, then doubled back heading east before finally heading northeast and running right into me.

Personally, I simply got lucky here that’s all with the way it all worked out and managed to fire first. Had I been a bit ahead of him, and maybe on the same layer I think he likely would have fired on me first, I am fairly confident that if I re ran the mission chances are he would get the better of me.

[Stewy1]

Thanks Kapitan - well done for the kill - and thank you for the incredible responses. I'm going to study them!

Sorry for uploading the wrong mission file - it's fixed now at https://www.subsim.com/radioroom/dow...o=file&id=6071

Wow - so you shot from 700 yards!! Talk about a knife fight! I suppose at that range, he wouldn't get a chance to fire back?

Thank you for your help.

And, I've nominated your post!
Stew

[Kapitan]

Thanks Stewy

At 700 yards the run time on that fish doing 35knots is going to be roughly 45 seconds.

I sometimes use a cheat sheet for conversions this might help you and it is faster than doing the math on the 3 or 6 minuet rules when things are moving quickly, I usually round up or down to make it easier.

Knots to Yards

You can Multiply this up for the hour (x60)

1 Knots to Yards Per Minute = 33.7562
2 Knots to Yards Per Minute = 67.5124
3 Knots to Yards Per Minute = 101.2686
4 Knots to Yards Per Minute = 135.0248
5 Knots to Yards Per Minute = 168.781
6 Knots to Yards Per Minute = 202.5372
7 Knots to Yards Per Minute = 236.2934
8 Knots to Yards Per Minute = 270.0496
9 Knots to Yards Per Minute = 303.8058
10 Knots to Yards Per Minute = 337.562
20 Knots to Yards Per Minute = 675.1239
30 Knots to Yards Per Minute = 1012.6859
40 Knots to Yards Per Minute = 1350.2479
50 Knots to Yards Per Minute = 1687.8099
60 Knots to Yards Per Minute = 2025.3718

Knots to Miles

You can divide this into minuets if required (/60)

1 Knots to Miles Per Hour = 1.1508
2 Knots to Miles Per Hour = 2.3016
3 Knots to Miles Per Hour = 3.4523
4 Knots to Miles Per Hour = 4.6031
5 Knots to Miles Per Hour = 5.7539
6 Knots to Miles Per Hour = 6.9047
7 Knots to Miles Per Hour = 8.0555
8 Knots to Miles Per Hour = 9.2062
9 Knots to Miles Per Hour = 10.357
10 Knots to Miles Per Hour = 11.5078
20 Knots to Miles Per Hour = 23.0156
30 Knots to Miles Per Hour = 34.5234
40 Knots to Miles Per Hour = 46.0312
50 Knots to Miles Per Hour = 57.539
60 Knots to Miles Per Hour = 69.0468

[Barleyman]

Someone actually managed to avoid a torpedo that's acquired your boat?

Usually my tactic is to say my prayers at that point and try to get the other guy with snapshot..

[Kapitan]

Yes there are ways to avoid, the trick is to be very very quick with your evasion if its close.

If the torpedo is coming at you in less than 1,500 yards your very unlikely to escape that.

You have a mediocre chance between 1,501- 4000 yards and beyond that it gives you time to move and reposition.

Typical tactic is to classify and confirm the inbound TIW, then turn while dropping CMs, sometimes diving deep doesn't help you the objective is to put distance between you and the torpedo you cant do that in a dive.

You will need to make a series of turns as well while dropping CMs

Your turns shouldn't really be more than 45 degrees in the opposing direction either.

[Barleyman]

For some reason my crew tends to have problems doing TMA on the torpedo to determine if it's heading in your way or not.. Once it's got your number and pinging merrily in your way you know for sure of course but it's a bit late at that point.

[Kapitan]

Auto crew can be a little slow at times, if its pinging i just use active intercept and assume its heading for me.