Depth Shallow

 

125 Battery Units

1st Hour @ 16kts = -15 units

110 Battery Units

 

2nd Hour @ 16kts = -15 units

95 Battery Units

Go to periscope depth IOT snort, decrease speed to 11kts

 

3rd Hour @ 11kts = -4 Units

91 Battery Units, but charging equals +10

101 Battery Units

Descend back to Shallow.

 

4th Hour @ 11kts = -4 Units

97 Battery Units remaining

 

30min @ 11kts

Contact, bearing 336 degrees. Attempted classification, Noisy Ship

 

3min Tactical Turn (1)

Lost passive contact

 

3min Tactical Turn (2)

Did not regain contact

 

3min Tactical Turn (3)

(Admin note: distance 1.6nm)

2D10 = 11 Contact, bearing 349 degrees, range 1.6nm

Classification attempt: (Noisy/ LF/MF = 10% + 10% target speed modifier = 20%. 2D10 =50. = SHIP.

Begin TMA Solution Attempt: Range: Short 30%/40%/50% per turn + 40% passive ranging array (PRA) sonar. 2D10 = 79. = FAIR solution.

 

3min Tactical Turn (4)

(Admin note distance 1.1nm) 75% Band <=1.6nm. +15 maintaining contact 2D10 = 75 – Contact maintained. Classification Attempt: 2D10 = 05, Merchant. 2nd TMA Attempt; Short Range; 30%x2 Turns = 60 +40% PRA Sonar = 100%; 2D10 = 25 GOOD SOLUTION. 2x SUT Mod2 torpedoes are to be fired, but not moved, in the Reaction Fire Phase.

 

3min Tactical Turn (5)

(Admin note distance 0.73nm) Movement Phase torpedoes @ 35kts move 1.75nm per Tactical Turn Movement Phase. EP: 500yds. At launch there is a 20% chance of the wire breaking regardless of the submarines status. 2D10 = 31. 2x SUT Mod2 WG Torpedoes at a 0.73nm, survives the wire breakage roll and traveling at 35kts. It's a 3rd Gen Torpedo with a 75% hit chance, an acquisition cone of +/-75 degrees, it travels 500 yards, turns on its seeker, and poof runs at the target. 2D10 (Torp 1) = 05 Hit, 2D10 (Torp 2) = 41 Hit. 260 DP’s on a 10,000ton displacement International Generic Merchant Ship. Damage Ratio calls for 10 Critical Hits, but decide to roll for sinking 3D6 = 5 = merchant sinks in 5 Tactical Turns or 15min (at the +5 Hour Game Clock).

 

Thanks to Tony's Plotter - Fun, lots of fun.

Nice write up. But whats this "Damage Ratio calls for 10 Critical

Hits, but decide to roll for sinking 3D6 = 5 = merchant sinks in 5

Tactical Turns or 15min (at the +5 Hour Game Clock" bit mean?

 

Is that a H4.1 rule?

 

I'm gaming two destroyers escorting 3 merchant ships. So there is 5

contacts in play and the sub can only fire on the destroyers.

Hi KC,

 

It is not an H4.1 rule what so ever. As far as I remember, hey it was over three years ago, I simply decided 10 critical rolls would most certainly leave it dead in the water...at least. I just rolled for it sinking.

Hi KC,

It is not an H4.1 rule what so ever.

 

 

Hahahaha. Yeah, not being critical at all. It was funny reading these AARs last night and realising myself they were 3+ years old! I've found them kinda inspirational for some of the small engagements i have going on.

 

I also go back from time to time for inspiration. Harpoon, coupled with the harpgamer guys help, has given me hours upon hours of fun exploring different ideas and theories.

 

Glad you enjoy them as well.

Instead of a new thread, i'm adding my latest submarine engagement to here.

 

I've just finished playing through one of the best engagements i've ever had. An LA class submarine began 30.0nm from a soviet Krivak IV frigate which was travelling away from the submarine at 20kts. The LA class sub detected the Krivak and gave pursuit. After 2 hours the distance was down to 6.0nm however neither unit had detected the other. The LA class sub had lost contact due to travelling so fast (30kts) to catch the Krivak.

 

Over the next 18 minutes both units were travelling slowly. The LA class trying to detect passively while the Krivak was searching actively. It took 18 minutes for the LA Class sub to detect and classify the Krivak, and get a good TMA solution for firing. Range was still 6.0nm when the LA class fired a fast moving torpedo (55kts with a range of 10.0nm) and a slow moving torpedo (40kts but with a range of 16.5nm). I decided to fire one of each because i wasnt sure if the fast moving torpedo would reach the target within its 10.0nm range.

 

It had been exhausting doing all the math and record keeping up to this point trying to close the distance to the Krivak, gain, maintain and classifying a contact and then trying to work out if it was worth closing the distance of 6.0nm to the target. Closing the distance made it easier to maintain detection and was better for the torpedoes (closer range and less time for the Krivak to run), but getting too close meant if contact was lost it would be harder to re-aquire. I decided to keep my distance from the Krivak and rely on having 3 turns to reaquire before loosing the +15% maintain contact bonus.

 

Eventually at the 2 hour 18 minute mark the Krivak was classified, a good TMA gained and two torpedoes were fired.

 

I thought the hardwork had been done and it was just going to be a matter of working out if the torpedoes hit and if so, what damage was done.

 

However, the Krivak detected the torpedo launch and sped up to 30kts. And this is where the scenario got interesting. At the time it frustrated me that more number cruching was needed, but by the end it was all worth it.

 

The high speed 55kts torpedo reached the Krivak. Before determining the hit chance i worked out the distance run by the torpedo and it worked out to be 11.0nm! Meaning the torpedo expired before reaching the Krivak.

 

The slow speed 40kts/16.5nm torpedo continued the chase and eventually caught the Krivak. Tentatively i worked out the length of the torpedo run and it came to 16.0nm! So the fleeing Krivak was caught just in time. The hit chance was 55%. And the torpedo missed.

 

I've paused the engagement there for now. Lots of fun. I didnt realise how close some of the decisions would turn out to be re distances and speeds. I only round distances to the nearest 0.1nm, maybe i need to be more precise in future.

 

Questions and comments:

1. 4.4.8 says torpedoes must be classified before a ship can take evasive manouvers or deploy countermeasures. The Krivak detected a contact using its active sonar (bearing and range only). I assumed the Krivak would be able to determine speed of the contact eventually at 55kts and "assume" it was a torpedo - this was logical to me. But maybe not in spirit of the rules. How does a ship using active sonar classify a torpedo, as far as i know it can only do that possively using its passive sonar.

 

2. The decision a submarine has to make to either close with a target (makes detection easier, TMA easier and better for fast torpedoes) or keep some distance (makes reaquiring a lost target easier and makes its own detection harder) is a toughy. But i guess thats what its all about.

 

3. A PC version of Harpoon would be good. But i enjoy being able to see what ranges and likelyhoods are for detecting and hitting contacts rather than just relying on being told by a radar or sonar in a computer game. You gain a much better understanding of why things do or dont happen when playing with the paper rules. It takes a bit longer but i am getting better and quicker at knowing what factors are involved and doing the maths.

1. 4.4.8 says torpedoes must be classified before a ship can take evasive manouvers or deploy countermeasures. The Krivak detected a contact using its active sonar (bearing and range only). I assumed the Krivak would be able to determine speed of the contact eventually at 55kts and "assume" it was a torpedo - this was logical to me. But maybe not in spirit of the rules. How does a ship using active sonar classify a torpedo, as far as i know it can only do that possively using its passive sonar.

 

Haven't you kinda answered your own question? Active sonar picks up a submerged contact on an intercept course and moving at 55 knots. What do you think it is?

In my book it is a question of how long to to do the TMA to determine the 55kt speed. With active sonar I'm guessing that will take at most 2 minutes with a decent staff. So I don't think the Krivak should run at the first hint of an active sonar detect but it also shouldn't take 10 minutes to confidently call the contact a torpedo.

In my book it is a question of how long to to do the TMA to determine the 55kt speed. With active sonar I'm guessing that will take at most 2 minutes with a decent staff. So I don't think the Krivak should run at the first hint of an active sonar detect but it also shouldn't take 10 minutes to confidently call the contact a torpedo.

 

Active sonar will give you the range to contact straight away, and with each pulse giving a new range, it shouldn't take long at all to establish a speed and course. See Rule 6.1.2 for TMA Procedure and the TMA Solution Quality Table on p6-3. With a 5.1 nm active sonar range for the Krivak IV's MGK-365 Zvezda (NATO Ox Yoke/Ox Tail) sonar suite, you get a 50% modifier. Active sonar shouldn't take long to 'classify' the contact as a torpedo.

I guess i was trying to positively identify the torpedo using a chart or rule - i thought that was what the rule was trying to say. But sure, a loud contact moving at 55kts sure sounds like a torpedoe. 4.4.8 specifically says a ship will not engage in evasive manouvers or speed up to outrun a torpedoe because its such a "noisy" thing to do, so without positive ID a contact cannot do it. I wasnt sure how else people were interprehting this.