OK guys, just finished writing up my first AAR. Its a fairly simple affair. Sorry its not written in a more exciting way but for now i was trying to make sure i could run something simple for myself. Comment away if you wish.

 

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LA class submarine heading east.

 

Akula class submarine (referred to as AK) heading west, on a collision course with the LA.

 

Yes, a simple and contrived scenario. But I’m more interested in working my way through the rules of Harpoon 4.1. This is my first attempt at it. I’ll reference rules along the way to either help others out or have people comment on my own interpretations.

 

LA speed (D20 die roll) is 11kts. AK speed is (D20) 9kts. Depth is the same, none is set though.

 

Both subs are using passive sonar. Sea state is 1. Before starting the game i worked out the chances of each detecting the other to save time and see what sort of range i was looking at to start.

 

LA passive sonar has a range of 5.1nm.

Using sonar range mods on page 4-11.

Multiplied by 0.5 for AK being very quiet.

Multiplied by 2.0 for target speed

Multiplied by lower of sea state 2.0 or own ships speed 1.0 (therefore use 1.0)

Calculation then is 5.1 * 0.5 * 2.0 * 1.0 = 5.1nm

75% = 5.1nm * 0.4 = 2.0nm (rounded to nearest decimal)

50% = 5.1 * 1.1 = 5.6nm

25% = 5.1 * 1.5 = 7.7 nm

 

AK passive sonar has a range of 3.4nm.

Using sonar range mods on page 4-11.

Multiplied by 0.5 for LA being very quiet.

Multiplied by 2.0 for target speed

Multiplied by lower of sea state 2.0 or own ships speed 1.0 (therefore use 1.0)

Calculation then is 3.4 * 0.5 * 2.0 * 1.0 = 3.4nm

75% = 3.4nm * 0.4 = 1.4 nm (rounded to nearest decimal)

50% = 3.4 * 1.1 = 3.7 nm

25% = 3.4 * 1.5 =5.1 nm

 

 

Tactical turns (3 mins) in effect

 

Time 0.00.0

Starting distance apart is set at 7.0nm to keep the encounter short.

Plot phase: Both move in straight line towards one another

Move: (combined closing speed is 20kts or 1.0nm per tac turn) so distance is reduced to 6.0nm

Detect: range is 6.0nm so LA has a 25% chance (rolled 38) therefore no detection. AK has no chance to detect (6.0nm is greater than AKs 25% limit of 5.1nm).

 

0.03.0 (tactical turns so 3 minutes later)

Plot phase: both units move in straight line

Move: due to combined closing speed, distance is now 5.0nm

Detect: LA now has a 50% chance of detecting, rolls 81 so picks up nothing. AK has a 25% chance to detect the LA, rolls 47 so it picks up nothing.

 

0.06.0

Plot phase: both units move in straight line

Move: due to combined closing speed, distance is now 4.0nm

Detect: LA has a 50% chance of detecting, rolls 80 so picks up nothing. AK has a 25% chance to detect, rolls 72 so picks up nothing.

 

0.09.0

Plot phase: both units move in straight line

Move: due to combined closing speed, distance is now 3.0nm

Detect: LA now has a 50% chance of detecting, rolls 25 so picks up a contact. Rule 4.4.8 Target classification comes into effect. Using table on page 4-11 VLF-LF and very quiet contact gives a base chance of 10%. Target speed of 9kts gives a further +5% so there is a 15% chance to classify target. Rolled 26 which is Pc (15%) + 20% so the LA sub can determine the contact is a Russian sub.

 

LA tries for TMA (6.2.1) using table on page 6-3.

Range is 3.0nm or medium. LA is using passive sonar so +20% modifier. Die roll is 43 which on the medium line is higher than good (required less than 40) but lower than fair (between 41-50), so a fair target solution exists.

 

AK has a 25% chance to detect, rolls 70 so picks up nothing.

 

LA decides to change to engagement turns (30 seconds)

 

0.09.5

1st + 2nd movement (combined to save time) – LA slows speed to 6kts. This reduces the AK chance to detect the LA because it has dropped from a target speed of 2.0 to 1.0 on the passive sonar table.

 

New combined closing speed is 9+6=15kts or 0.06nm per engagement turn (I rounded up to 0.1nm for ease)

 

Range is now 3nm less 0.1 = 2.9nm

 

1st Fire phase – LA fires 2 Mk 48 torpedoes using Fair TMA. My understanding is a TMA can only be attempted once per tactical turn (rule 6.1.2) and I wanted to fire early rather than wait so I used the fair TMA gained earlier (rules check anyone?)

 

Rule 5.5.4 says 20% chance of wire breaking on each torpedo at launch. Rolls 03 and 15 so neither wire breaks. There is no need to check for breakage again unless LA changes course or speed/depth (5.5.4). There is no need to roll to hit yet, because the torpedo has not “arrived” on target.

 

Detect phase – AK is most likely to detect the firing of the torpedo (masking rule 4.4.5.2). Calculations are

AK passive sonar has a range of 3.4nm.

Using sonar range mods on page 4-11.

Multiplied by 2.0 for torpedo being noisy.

Multiplied by 8.0 for target speed (55kts)

Multiplied by lower of sea state 2.0 or own ships speed 1.0 (therefore use 1.0)

Calculation then is 3.4 * 2.0 * 8.0 * 1.0 = 54.4nm

75% = 54.4nm * 0.4 = 21.7 nm which is well within range of both the sub and torpedo so no need to work anything else out.

AK rolls 92 to detect (greater than 75% !), so picks up nothing.

 

The LA sub is happy to go back to tactical turns (3 mins).

 

(Rules check) This is where I am unclear on a rule. The AK sub has not detected anything, and has no reason to suspect it has been fired upon. So can the owner of the AK choose to go to engagement turns where he has an opportunity to pick up the torpedo and LA at a longer range than if tactical turns were being used?

 

If engagement turns are being used there is a 0.5 penalty, but given the close range it wont change anything. There is still a 75% chance each 30 seconds of picking up the torpedo. If we use tactical turns, the torpedo will be much much closer (6 times closer) before the AK can try to detect the torpedo again using 3 minute turns. And by then it might even have impacted. Any comments on this would be great.

 

For sake of argument, AK chooses to keep engagement turns (30 seconds).

 

 

0.10.0

Two movement phases combined. The two subs closing speed of 15kts is unchanged so range is now 2.8nm. Closing speed of torpedo and AK is 9 + 55 = 64 kts or 0.3nm per engagement turn so range has fallen to 2.6nm.

 

AK to detect is 75% rolls 48 so detects “something”.

 

4-11 passive sonar classification calculations

LF-MF and noisy target is a base of 10% and passive torpedo +20% so 30% chance. Rolls 75. Roll of 75 is higher than 30% + 41% so no data is able to be determined.

 

At this point, I decided to stay with tactical turns (3 mins).

 

0.13.0

The torpedo and AK combine to move 3.2nm in the tactical turn which is more than the 2.6nm required, so I can roll for the torpedo to hit.

 

The LA and AK subs are 2.8 less 0.8nm = 2.0nm apart.

 

So, the to hit roll for the torpedo. Page 6-28 shows homing torpedoes with wires attached table.

 

Generation 3 Mk 48 torpedoes against Generation 3 ACM of AK submarine gives a to hit probability of 75%. The AK has not detected the torpedo so there are no modifiers for countermeasures or manoeuvring.

 

The to hit probability of 75% is adjusted by our “fair” TMA, so 75 * 0.8 from the Homing torpedo TMA solution table on page 6-30 gives a to hit chance of 60% for each torpedo.

 

To hit rolls of 54 and 62 so one hits.

 

Moving into chapter 7 for damage then.

AK has 138 hit points and takes 75 damage points from the torpedo, leaving it 63 points. For critical hits damage ratio is 75/63 = 1.19 but I’ll use the 1.0 line on the table on page 7-2.

D6 roll of 2 = 7 critical hit rolls. I havent worked out details past this point yet.

 

 

 

Areas of improvement

 

Can a player switch to engagement turns to detect contacts earlier than if using tactical turns? The player knows it may help him, but the units involved don’t know anything so … the player being able to use the rules to his advantage seems to be “against the spirit” of the rule. If a player had a contact but could not identify it, then I would agree using engagement turns should be available.

 

If TMA of fair is gained, can a better TMA be rolled for in the next engagement turn? Or can a TMA only be attempted each tactical turn?

 

I’m pretty sure the AK submarine has Anechoic coating, so that should have been another 0.5 on the sonar range or affected the torpedo somehow.

 

I have assumed after the torpedo is “fired” nothing else needs to be done. But after more reading I suspect I should have nominated the torpedo as passive until the range decreased to say, 1.0nm and then had it go “active”. This also would have been another chance for the AK to detect the torp (going active might be an automatic detection of the torpedo?). And then allowed the AK to take evasive manoeuvres or deploy counter measures.

 

Does ESM apply to subs?

 

Rule 4.4.3 talks about maintaining contact with known contacts. So I think the LA needed to roll to maintain the known AK (with a +15% for known contact). This roll should have occurred before the torpedo had a chance to hit.

 

The LA did not choose to “cut the wires” of the torpedo at any point, and maybe that’s something that should have happened.

 

This was a pretty simple example, but it gets you using allot of the rules.

 

 

Simplified flowchart of order rules used after movement and detection

Sonar detection 4.4 for contact

Target classification attempt 4-11

TMA solution 6.1.2

Fire torpedo (does wire break 5.5.4)

To hit chance 6.5.1

KC, I'm reading through the above, unfortunately I did not grab my 4.1 on the way out today so there may be no comment from me until later today at the earliest.

 

Good to see that you jumped right in. After first trying ASW and having a hard time with it, I went on to other "disciplines" ASuW, AAW, strike warfare before going back to subs. I had no prior naval gaming experience, other than HC97 when I picked up 4/4.1.

 

Pete

I don't usually have the H4/4.1 rules in front of me, either, and would defer to Pete on the finer points of the rules anyway. But its cool to see you "diving" into it, so to speak, and I'll offer some comments.

 

Does ESM apply to subs?

 

Yes, but only when they're surfaced (and the ESM mast goes up).

 

The LA did not choose to “cut the wires” of the torpedo at any point, and maybe that’s something that should have happened.

 

Generally speaking, a launching submarine would only cut the wires if it wished to maneuver immediately after shooting (and if the maneuver was severe enough, the wires would break anyway), and in most cases will want to maintain that control for as long as possible. If a sub is confident in his tactical position and self-noise, he may not want to cut the wires until the last possible moment or at all.

thanks guys. For some reason i thought sub v sub would be the easiest place to start.

 

This is my first time playing any sort of navel game.

 

IF you do have comments at any time, throw them in.

 

Thanks for the answers to questions.

 

I'm hoping to get a chance to run through another simple encounter soon, and write it up.

thanks for the feedback, and answering some of my questions.

 

for some reason i thought sub v sub would be the easiest place to start.

 

i hope to get another small encounter and AAR up soon. If anyone else has AAR's, it would be good to see them get posted up.

KC, I'll be able to step through your sub v. sub this afternoon. I have not had my H4.1 out for a couple months now so stepping through would be best.

 

I'll be in touch,

 

Pete

for some reason i thought sub v sub would be the easiest place to start.

 

Not a problem, just my personal experience, and it was probably just me.

 

If anyone else has AAR's, it would be good to see them get posted up.

 

Scrolling through any of the three H4 categories here you will see examples of my toils and folly. Many are cross posted on the Admiralty Trilogy and/or A Willing Foe yahoo groups.

Both subs are using passive sonar. Sea state is 1. Before starting the game i worked out the chances of each detecting the other to save time and see what sort of range i was looking at to start.

 

LA passive sonar has a range of 5.1nm.

Using sonar range mods on page 4-11.

Multiplied by 0.5 for AK being very quiet.

Multiplied by 2.0 for target speed

Multiplied by lower of sea state 2.0 or own ships speed 1.0 (therefore use 1.0)

Calculation then is 5.1 * 0.5 * 2.0 * 1.0 = 5.1nm

75% = 5.1nm * 0.4 = 2.0nm (rounded to nearest decimal)

50% = 5.1 * 1.1 = 5.6nm

25% = 5.1 * 1.5 = 7.7 nm

 

Your accounting for all of the factors and calculations appear good. What type of sonar are you using here? While I have my rules and am following your caluclations, I did not have my data annex within my rules binder. An "own ships speed" factor of 1, considering the LA's noted speed of 11kts would mean the sonar being used would have to be a High Speed Towed Array, which may be the case. The differences between low and high speed towed arrays are ever so briefly discussed within 4.4.2.3 Towed Arrays, just past mid way down in the left hand column. Without my annex, I'm at a disadvantage and may just be muddying up the waters.

 

AK passive sonar has a range of 3.4nm.

Using sonar range mods on page 4-11.

Multiplied by 0.5 for LA being very quiet.

Multiplied by 2.0 for target speed

Multiplied by lower of sea state 2.0 or own ships speed 1.0 (therefore use 1.0)

Calculation then is 3.4 * 0.5 * 2.0 * 1.0 = 3.4nm

75% = 3.4nm * 0.4 = 1.4 nm (rounded to nearest decimal)

50% = 3.4 * 1.1 = 3.7 nm

25% = 3.4 * 1.5 =5.1 nm

 

Same-Same here. AK speed of 9kts would mean it too was employing a high speed array for the factor to be 1.

 

Tactical turns (3 mins) in effect

 

Time 0.00.0

Starting distance apart is set at 7.0nm to keep the encounter short.

Plot phase: Both move in straight line towards one another

Move: (combined closing speed is 20kts or 1.0nm per tac turn) so distance is reduced to 6.0nm

Detect: range is 6.0nm so LA has a 25% chance (rolled 38) therefore no detection. AK has no chance to detect (6.0nm is greater than AKs 25% limit of 5.1nm).

 

0.03.0 (tactical turns so 3 minutes later)

Plot phase: both units move in straight line

Move: due to combined closing speed, distance is now 5.0nm

Detect: LA now has a 50% chance of detecting, rolls 81 so picks up nothing. AK has a 25% chance to detect the LA, rolls 47 so it picks up nothing.

 

0.06.0

Plot phase: both units move in straight line

Move: due to combined closing speed, distance is now 4.0nm

Detect: LA has a 50% chance of detecting, rolls 80 so picks up nothing. AK has a 25% chance to detect, rolls 72 so picks up nothing.

 

0.09.0

Plot phase: both units move in straight line

Move: due to combined closing speed, distance is now 3.0nm

Detect: LA now has a 50% chance of detecting, rolls 25 so picks up a contact. Rule 4.4.8 Target classification comes into effect. Using table on page 4-11 VLF-LF and very quiet contact gives a base chance of 10%. Target speed of 9kts gives a further +5% so there is a 15% chance to classify target. Rolled 26 which is Pc (15%) + 20% so the LA sub can determine the contact is a Russian sub.

 

Yes, a VLF-LF against a Very Quiet contact gives a baseof 10%, plus 5% for the target's speed of 9kts. The way that I have played it is that since you rolled 26, within 16-35 (your 15+20) you know that it is a submarine, its propulsion type and nationality. Had you rolled <15 you would know so far as the class of the opposing sub.

 

LA tries for TMA (6.2.1) using table on page 6-3.

Range is 3.0nm or medium. LA is using passive sonar so +20% modifier. Die roll is 43 which on the medium line is higher than good (required less than 40) but lower than fair (between 41-50), so a fair target solution exists.

 

TMA procedure looks good. Problem often is that a Fair TMA is not very encouraging. Each tactical turn, or its equivelent, you you can roll for a better solution. Your solution will only degrade if the target changes course or speed, or if you fail to maintain passive sonar contact with the target. Maintaining contact has been the bugger for me in my gaming.

 

AK has a 25% chance to detect, rolls 70 so picks up nothing.

 

LA decides to change to engagement turns (30 seconds)

 

0.09.5

1st + 2nd movement (combined to save time) – LA slows speed to 6kts. This reduces the AK chance to detect the LA because it has dropped from a target speed of 2.0 to 1.0 on the passive sonar table.

 

New combined closing speed is 9+6=15kts or 0.06nm per engagement turn (I rounded up to 0.1nm for ease)

 

Range is now 3nm less 0.1 = 2.9nm

 

1st Fire phase – LA fires 2 Mk 48 torpedoes using Fair TMA. My understanding is a TMA can only be attempted once per tactical turn (rule 6.1.2) and I wanted to fire early rather than wait so I used the fair TMA gained earlier (rules check anyone?)

 

I do not believe anything prevents you from firing with a poor TMA solution, but its not considered poor for no reason.

 

 

Rule 5.5.4 says 20% chance of wire breaking on each torpedo at launch. Rolls 03 and 15 so neither wire breaks. There is no need to check for breakage again unless LA changes course or speed/depth (5.5.4). There is no need to roll to hit yet, because the torpedo has not “arrived” on target.

 

Detect phase – AK is most likely to detect the firing of the torpedo (masking rule 4.4.5.2). Calculations are

AK passive sonar has a range of 3.4nm.

Using sonar range mods on page 4-11.

Multiplied by 2.0 for torpedo being noisy.

Multiplied by 8.0 for target speed (55kts)

Multiplied by lower of sea state 2.0 or own ships speed 1.0 (therefore use 1.0)

Calculation then is 3.4 * 2.0 * 8.0 * 1.0 = 54.4nm

75% = 54.4nm * 0.4 = 21.7 nm which is well within range of both the sub and torpedo so no need to work anything else out.

AK rolls 92 to detect (greater than 75% !), so picks up nothing.

 

See 4.4.5.1.2 Launch Transients if you have not already done so. Akula is rolling horribly...for them of course.

 

The LA sub is happy to go back to tactical turns (3 mins).

 

(Rules check) This is where I am unclear on a rule. The AK sub has not detected anything, and has no reason to suspect it has been fired upon. So can the owner of the AK choose to go to engagement turns where he has an opportunity to pick up the torpedo and LA at a longer range than if tactical turns were being used?

 

If engagement turns are being used there is a 0.5 penalty, but given the close range it wont change anything. There is still a 75% chance each 30 seconds of picking up the torpedo. If we use tactical turns, the torpedo will be much much closer (6 times closer) before the AK can try to detect the torpedo again using 3 minute turns. And by then it might even have impacted. Any comments on this would be great.

 

I'd probably keep it at Tactical Turns, unless the Akula was at some scenario-dependent heightened alert level despite not having made any contact. Engagement turns are described to be used for high speed air units in 2.2.4.

 

Looks like you are picking up on it well. More to follow later.

 

Pete

Well for the sake of argument, my High Tide Data Annex shows Los Angeles Class SSN with BQQ-5C/D, TB-16D and TB-23 towed arrays. Also, Improved Los Angeles Class SSN with BSY-1, TB-16D and TB-23 Towed Arrays. So with a base passive sonar range of 5.1nm I'd say that you were most likely using the TB-16D/E VLF-LF High Speed, short towed array found on either the LA or LAi.

 

For sake of argument, AK chooses to keep engagement turns (30 seconds).

0.10.0

Two movement phases combined. The two subs closing speed of 15kts is unchanged so range is now 2.8nm. Closing speed of torpedo and AK is 9 + 55 = 64 kts or 0.3nm per engagement turn so range has fallen to 2.6nm.

 

AK to detect is 75% rolls 48 so detects “something”.

 

4-11 passive sonar classification calculations

LF-MF and noisy target is a base of 10% and passive torpedo +20% so 30% chance. Rolls 75. Roll of 75 is higher than 30% + 41% so no data is able to be determined.

 

Sounds good so far...to me at least.

 

At this point, I decided to stay with tactical turns (3 mins).

 

0.13.0

The torpedo and AK combine to move 3.2nm in the tactical turn which is more than the 2.6nm required, so I can roll for the torpedo to hit.

 

The LA and AK subs are 2.8 less 0.8nm = 2.0nm apart.

 

So, the to hit roll for the torpedo. Page 6-28 shows homing torpedoes with wires attached table.

 

Generation 3 Mk 48 torpedoes against Generation 3 ACM of AK submarine gives a to hit probability of 75%. The AK has not detected the torpedo so there are no modifiers for countermeasures or manoeuvring.

 

The to hit probability of 75% is adjusted by our “fair” TMA, so 75 * 0.8 from the Homing torpedo TMA solution table on page 6-30 gives a to hit chance of 60% for each torpedo.

 

To hit rolls of 54 and 62 so one hits.

 

Moving into chapter 7 for damage then.

AK has 138 hit points and takes 75 damage points from the torpedo, leaving it 63 points. For critical hits damage ratio is 75/63 = 1.19 but I’ll use the 1.0 line on the table on page 7-2.

 

The note below the table says higher ratios should be extrapolated, but I understand that in a solo learning exercise 1.0 is good enough to get the procedure down.

Areas of improvement

 

Can a player switch to engagement turns to detect contacts earlier than if using tactical turns? The player knows it may help him, but the units involved don’t know anything so … the player being able to use the rules to his advantage seems to be “against the spirit” of the rule. If a player had a contact but could not identify it, then I would agree using engagement turns should be available.

 

I would play it that one opposing units enter detection range using Intermediate or maybe even Tactical Turns, I'd back out then switch to the shorter respective turn. As you acknowledged seems to be against the spirit of the rule, but your playing solo so your mileage may vary.

 

If TMA of fair is gained, can a better TMA be rolled for in the next engagement turn? Or can a TMA only be attempted each tactical turn?

I am fairly certain the TMA solutions are attempted once per Tactical Turn. These are apparently slow, methodical, tedius, bordering on mind-exploding processes.

 

I’m pretty sure the AK submarine has Anechoic coating, so that should have been another 0.5 on the sonar range or affected the torpedo somehow.

 

My High Tide Annex has the Project 941 Akula [Typhoon] SSBN having anechoic coating so there would be an Active Sonar Special Modifier of x.5 range modifier.

 

I have assumed after the torpedo is “fired” nothing else needs to be done. But after more reading I suspect I should have nominated the torpedo as passive until the range decreased to say, 1.0nm and then had it go “active”. This also would have been another chance for the AK to detect the torp (going active might be an automatic detection of the torpedo?). And then allowed the AK to take evasive manoeuvres or deploy counter measures.

 

That sounds like establishing an Enabling Point. Once the seeker is active it would result in a Target Correlation Modifier found with the Passive Sonar Classifications on Page 4-11. I would suspect that a better TMA solution would counter act some of the drawback of going active, but I would need to look into that situation a little further.

 

Does ESM apply to subs?

Think Brad already answered that, only at periscope depth with the periscopes or other masts above the surface.

 

Rule 4.4.3 talks about maintaining contact with known contacts. So I think the LA needed to roll to maintain the known AK (with a +15% for known contact). This roll should have occurred before the torpedo had a chance to hit.

 

While the torpedo is moving yes, the turn that it reaches the target, it is resolved in that Tactical Turns Movement Phase, before the Detection Phase.

 

The LA did not choose to “cut the wires” of the torpedo at any point, and maybe that’s something that should have happened.

 

You would want the wires for guidance. Wires possibly break upon launch, and again if the firing sub takes some type of evasive action, it may choose to cut the wires. Much to the detriment of the pH of that torpedo.

 

This was a pretty simple example, but it gets you using allot of the rules.

But a very good way to get many of the procedures down without over complicating the situation.

 

Simplified flowchart of order rules used after movement and detection

Sonar detection 4.4 for contact

Target classification attempt 4-11

TMA solution 6.1.2

Fire torpedo (does wire break 5.5.4)

To hit chance 6.5.1

 

I'm no expert, but all and all, very good, thorough job.

My High Tide Annex has the Project 941 Akula [Typhoon] SSBN having anechoic coating so there would be an Active Sonar Special Modifier of x.5 range modifier.

 

Is kcdusk referring to the Project 971 Shchuka-Bars [Akula] class SSN? (Still has the anechoic coating, though).

Is kcdusk referring to the Project 971 Shchuka-Bars [Akula] class SSN? (Still has the anechoic coating, though).

 

He'll have to chime in on that. Once I starting going through it I realized that I had to make some assumptions in order to continue. All in the spirit of theAAR of course.

My High Tide Annex has the Project 941 Akula [Typhoon] SSBN having anechoic coating so there would be an Active Sonar Special Modifier of x.5 range modifier.

 

Is kcdusk referring to the Project 971 Shchuka-Bars [Akula] class SSN? (Still has the anechoic coating, though).

 

I'd say the 971. NATO Reporting Names can be confusing...

Is kcdusk referring to the Project 971 Shchuka-Bars [Akula] class SSN? (Still has the anechoic coating, though).

 

He'll have to chime in on that. Once I starting going through it I realized that I had to make some assumptions in order to continue. All in the spirit of theAAR of course.

 

 

KC...are you out there? Hope all is well.

 

We need more H4.1 talk here.

Under what conditions do subs use their towed array? Is it only when they are slowly trawling for contacts, then they retract it during combat?