NYGM 2.2 Escort Logic Question

[SubConscious]

I'm on my second patrol, it's November 13, 1939 and I'm in a VIIB off the southern coast of Ireland. I was sinking a tugboat with deck gun and 20mm fire when two destroyers came on the scene. Not a problem, I'm figuring the tugboat sent out a distress call.

So I crash dive deep, make a 90 degree turn, drop my speed to 1 knot and start trying to minimize my profile to the escorts. They manage to blow off one of my rudders, but I don't take any other serious damage, with hull efficiency at 99%.

A few game hours pass and I notice a third escort on the scene. Then a fourth. Then a fifth. I see on the navigation map that I'm near fairly deep water (200+ meters), so I creep for it, still trying in vain to evade.

Having reached the deep water, I wait for a depth charge attack. Once it arrives (didn't have to wait long with six escorts on me), I killed my engines and let my boat settle to the bottom, which was 211 meters. After several hours, a sixth escort arrived on the scene.

Ok, so that's the scenario. These six escorts have been on station for so long, well over 24 hours, that I'm at about 20% oxygen and they're showing no signs of giving up.

Here's my question: Is this realistic? I can't recall a single instance of a U-boat being hounded by six escorts for this long, especially in 1939. I can't see why a pair of destroyers would need to call for reinforcements unless they ran out of depth charges. Once my boat when to the bottom, I could see leaving 1-2 escorts on station to wait and listen, but all six?

Any clarification would be greatly appreciated. Thanks! ;)

[SubConscious]

Post mortem: I ran out of oxygen while trying to get to the surface, though I certainly would have been demolished had I suceeded in getting there, as I was surrounded. I thought it was interesting that I received the "instant death" screen, indicating "Not enough crew".

I took a look with the external camera just before all of my crew died at the same time. One of the escorts had moved off. The remaining five were three Tribal class Destroyers and two C-Class Destroyers.

Ouch. :-?

[Der Teddy Bar]

SubConscious,
This is a great result for the NYGM BIE Mod. I hope the exerts below make your loss easier to come to terms with.

I quote from page 68 in the book 'The War at Sea 1939-1945' by Captain S. W. Roskill DSC, RN

On the 19th of September a report was received by Admiral Forbes that a U-Boat was stopping and sinking fishing trawlers off the Butt of Lewis. He at once sent 10 destroyers and naval aircraft to hunt her and the result was the sinking, the next day, of U 27 and the capture of her crew

There was no doubt that, once asdic-fitted vessels knew where to seek their quarry and enough of them could be spared to do the job properly, a promply executed hunt could achieve success - especially if aircraft were there to help.


Sumerised from pages 46-49 of the book 'U-boat Ace The story of Wolgang Luth' by Jordan Vause

On the 24th of May at 0300 after attempting to attack 2 escorts (?) he was detected and counter attacked and damaged. At 0700 he played dead , at 1100 he had patash cartridges passed out,.

Finally in late afternoon one of the warships dropped a marker buoy over U 9's position... more charges were dropped...

At 0024, after 21 hours underwater... Luth emerged and imediately , about 300 metres away, confronted the dark presence of a British destroyer....


There are more such stories in the 1st & 2nd U-Boat Flotilla books.


The NYGM British Isles Escort Mod v1 has NO scripted escorts anywhere around the English Isles. That’s right, none, all escorts are continually generated and are deleted at the end of the plotted course. Eventually we will replace the escorts at Gibraltar, in the Med and along the American East Coast etc.

To presume that the NYGM British Isles Escort Mod will make it harder is only partially correct. The NYGM British Isles Escort Mod v1 is more than just removing the ‘canned’ escorts which made traversing the English Channel in 1945 a walk in the park. As always, NYGM are aiming to replicate the historical conditions, and in some cases, particularly early war this may result in certain areas having less escorts.

What is so exciting about the NYGM British Isles Escort Mod is the randomness. Escorts now have random patterns with unlimited way points ranging from 5 up to 300 kilometres on radius and at each way point there is a random chance of a course change.

The randomness of the escort’s course will create a very dynamic environment. The dynamic numbers are achieved through course variations that result in escorts sometimes staying longer or even leaving early. For example, in the Dover straights I have seen instances where there were 10 escorts making it suicidal to try and pass, yet at other times there were only 2 escorts making passage through the Dover straights a breeze. For a more specific example, on September 10, 1939 you may not be able to pass through the Dover straights, however on September 12, 1939 the passage is possible due to fewer escorts or the escort’s location/s.

Escorts will also more often than not, now travel in groups of 2+. While there will be singular escorts, for the majority, there will be either 2 or 3 escorts in a group, including Elco’s. In the extreme but rare instances, where the random chance has played its part, there may be up to 5 destroyers is a group!

The escorts groups will also be spread out over a large area, sometimes up to 2000 metres. This will for the most part make attacking an escort group a very poor choice and a very risky proposition.

The escort groups start and finish essentially in port. I have done this for several reasons, firstly, that is where they should start and finish at! It gives a sense of realism seeing the escorts coming and going from a ‘port’ to other areas and in addition it reduces the need for port specific escorts, especially at the start of the war.

For example, the escorts going and returning from Southend to Dover or Lowestoft are creating enough escort traffic to not warrant any dedicated escort for the Southend-on-sea area. The same goes for the Northern Channel where the escorts travelling from the Firth of the Clyde to the Northern Approaches and to the Irish Sea negate the need for channel specific escort/s.

This is not to say that port specific escorts, conforming to the British Isles Escort Mod principles are not required or should not be added. Even with the large amount of traffic starting from and returning to the Firth of Forth it has been necessary to add a dedicated escort route.

These are some examples (not a complete list) showing the port the escorts start and finish at and the destination:
Firth of Forth travel to Hartlepool, Hull, Inverness & Lowescroft.
Firth of the Clyde travel to the Northern Approaches & the Irish Sea.
Bristol travel to the Bristol Channel & the Celtic Sea.
Portsmouth travel to the Southern Approaches and the English Channel
Southend travel to Dover & Lowestoft
Loch Ewe travel to Loch Ewe and Hebrides
Scapa Flow travel to the Faeroes & Shetlands

The waypoints have been laid out to best cover the specific area and no two courses, even if in the same area, are the same in layout or waypoint variation. You will have great difficulties in learning an escort’s path, I would go so far as to say, it will be near impossible. You will need to pay particular attention as there is always a chance of the escort/s that you saw leave will come back, either directly through the default course or through a course variation.

For example, you see an escort in grid AM92, or for this escort, waypoint 10. The escort passes by and you are not detected.. There is a chance that the escort may double back either indirectly or directly.

Indirectly in that the next waypoints 13, 14 & 15 in grid AM68 may have the escort passing back through AM92 again.
Indirectly where waypoint 12 might have a % chance that the escort will loop back to waypoint 8 and then onto waypoint 9, 10 etc.
Directly in that the next waypoint, 11 may be have a % chance of the escort returning to waypoint 10.

Not all waypoints double back, some do skip forward. However you should never assume that an escort will not return within a very short space of time.

Escorts now cover a much larger patrol area. For example, escorts in the Irish Sea will take in these grids, AM67, 68, 91, 92, 94, 94, 97 & 98.

With escorts now covering a larger patrol area the chances of an escort responding to a merchant ship sighting you also increases. So there will be few places where you can leisurely attack a merchant ship without concern of an escort responding.

Remember that while the NYGM British Isles Escort Mod looks very busy, the escorts are randomly generated and after completing the designated route exit from the game. In 1939 it is possible for example, to travel from St Georges Channel through to the beginning of the North Passage without encountering a single escort, of course other times you may encounter several. That is the beauty of this mod.

http://img177.imageshack.us/img177/7224/nygmbiemodyear1939ad4.jpg

http://img111.imageshack.us/img111/5007/shiiiescortsyear1939ha2.jpg

http://img98.imageshack.us/img98/8281/nygmbiemodyear1945fc5.jpg

http://img69.imageshack.us/img69/480/shiiiescortsyear1945nf3.jpg

[Immacolata]

Hmm. Interesting. Once around summer 1942 we were harassing a convoy heading to America, somewhere east of Greenland. I hit it over three nights, and I noticed when I surfaced the third night after my last attack that a lot of boats were trailing the convoys. A transport, and at least 3 warships of some kind. This was in addition to the two warships sailing escort. They were perhaps 5-10 nm behind. And they definitely was not there when I met the convoy first time. Have they been assigned by the AI or was it just a lucky coincidence that an ASW task force was following the same route?

[LaikaFatBum]

:o I am forever amazed at what dtb and crew do.
They always thinking outside the square. how many in NYGM cause they do so many new things alll the time.

[SubConscious]

Thank you, Der Teddy Bear, for your very informative and thoughtful reply. For the record, I don't have a problem with my sub being sunk, as we all know that the odds are definitely stacked against the U-boat. ;)

I've been doing some research into the fates of U-boats and trying to come up with predictor variables. According to my notes, U-27 was sunk by British destroyers HMS Fortune and HMS Forester. This is not to say that the other 8 destroyers didn't participate, just that they weren't credited for the sinking.

From what I have read, there were a total of 16 Tribal Class Destroyers in the Royal Navy. I thought it was unusual to see three of them in such close proximity, but I suppose this isn't outside the realm of possibility.

To clarify: The initial pair of destroyers that I encountered consisted of one Tribal and one C-Class. The other three destroyers (and one other escort I didn't identify before sinking) came on station later. This was another aspect that I thought was odd, but apparently not totally improbable (just unlucky on my part ;) ).

The other question you answered (the one I have been intending to ask) was about the efficacy of attempting to sink escorts - whether doing so would eliminate that ship from the enemy's roster so that it couldn't be encountered again (potentially a good early war strategy, prior to the Lend-Lease act). I figured that this would be a nightmare to code and didn't expect it to be a very likely possibility. Still, it's good to have the confirmation that sinking escorts would only have limited short-term benefits.

I have been enjoying NYGM TW 2.2 immensely and will no doubt continue to do so. Thank you and your development team for putting together such an enjoyable mod and for your willingness to be so responsive to questions. :up:

[caspofungin]

I thought it was unusual to see three of them in such close proximity

actually, the rn often had flotillas consisting of a single class of destroyers, so seeing 2 or more of single type of dd together wouldn't have been unusual

[Ducimus]

SubConscious

Bottoming the boat will not help you in SH3. You have to lose contact with them on passive and actve sonar for however long the lost contact time is, as defined by the sim.cfg file. (if its 30 to 40 mins, you have to not allow them to regain contact with you for the next 30- 40 mins if they're to go away.)

211 meters is not deep enough to get under their sonar cone most likely. So long as they get a contact, they'll probably never go away, and anytime a ship "spots" or otherwise contacts a sub, any warship/plane in the area will respond if it the time to get to the broadcasted location is within the lost contact time. IE, if your 30 mins away and the lost contact time is 40, you'll have a new friend joining the party.

[Der Teddy Bar]

SubConscious

Bottoming the boat will not help you in SH3. You have to lose contact with them on passive and actve sonar for however long the lost contact time is, as defined by the sim.cfg file. (if its 30 to 40 mins, you have to not allow them to regain contact with you for the next 30- 40 mins if they're to go away.)

211 meters is not deep enough to get under their sonar cone most likely. So long as they get a contact, they'll probably never go away, and anytime a ship "spots" or otherwise contacts a sub, any warship/plane in the area will respond if it the time to get to the broadcasted location is within the lost contact time. IE, if your 30 mins away and the lost contact time is 40, you'll have a new friend joining the party.
Good advice.

May I also add that next time there may not be additional escorts turn up. But are you willing to risk that? :hmm:

[SubConscious]

Ducimus,

Thank you very much for bit of information. I was just wondering why the escorts were pursuing me when historically, the British didn't know how deep U-boats could go until they captured one. Using this logic, I figured that suddenly stopping both maneuvering and engines immediately after a depth charge attack and drifting to the bottom would be recognized as a "kill" (though I was sorely tempted to blow some ballast to give the ruse a greater effect). One never knows how the "logic" of the code is written until one asks.

...or until a generous person such as yourself offers the information. Thanks for the enlightenment! :know:

[Hartmann]

Two lessons learned .. today :hmm:

Don´t stop in the bottom , continue moving very deep at low speed

And not risk your boat sinking small tug boats in dangerous waters, unless you can run away some miles and dive until the night fall
also tug boats where used as a inteligence ships for weather and submarine repports. :dead:

[SubConscious]

Two lessons learned .. today :hmm:

Don´t stop in the bottom , continue moving very deep at low speed

And not risk your boat sinking small tug boats in dangerous waters, unless you can run away some miles and dive until the night fall
also tug boats where used as a inteligence ships for weather and submarine repports. :dead:

Aye - two lessons learned the hard way! ;) Silly me, I was trying to save ammunition by first knocking out the Tug Boat's engine room with my 88mm, then finishing the job with the 20mm. It worked - the Tug sank, but the final cost was too high due to my own ignorance of the aforementioned facts. :oops:

Live and learn... or in this case, sink and learn.

[Ducimus]

The AI, really isnt much of an AI at all. It's very mechanical; at least i think so. Certain criteria have to be met in order to illicet a response from a DD/DE. If your actions do not meet the criteria the game looks for, the "AI" simply does whatever. The AI is rather booean in nature.

Randominess in their attacks seems primarly through enviormental variables on weather or not they see you to begin with, variables that effect their accuracy, or crew ratings which i beleive effect threshold response values. Honestly having a fairly good idea on how the AI works isnt very fun, takes all the mystique out of the game and turns it into a mechanical exercise.

[SubConscious]

I fully agree with your last sentence - a fully predictable game is a boring exercise. My focus has been to ascertain the amount and type of realism I can expect. For example, I think the BDu could have benefited from targeting escorts early in the war - not to the exclusion of merchants, but for the long-term benefit of depleting the escorts available for convoy duty, much in the same way the Luftwaffe targeted British airfields and aircraft factories in preparation for Sea Lion. If, however, this strategy isn’t a viable option in the game, then attempting to pursue this course of action would be an exercise in frustration, as the enemy now has an unlimited supply of each type of escort.

In the same vein, I think it’s good to know some basic tactics for eluding escorts. Certainly U-boat Commanders would talk about what works for them, much in the same way we do here on the forums. In gathering this information, I try to process the practical details rather than the coding logic behind them, e.g., from your last post, I’ll try to go deeper and evade rather than sitting on the bottom and waiting: The software reasons why I’m doing this aren’t important to me, at least at this writing. ;)

All in all, it's a wonderful game. There are some holes here and there, but they're pretty easy to work around.

Thanks again for sharing your wisdom.

[Ducimus]

Well, this isnt any big secret, but, As active sonar goes. From what i can tell, the AI uses its active sonar when:

- your within it's sonar's cone, (see pic)
http://www.de220.com/Electronics/Sonar/Sonar%20Photos/Sonar%20Patterns.jpg

- your presenting a favorable aspect, (IE broadside)

-AND your doing both of the above for X number of seconds or minutes.

If all three criteria arent met, you wont hear much out of the AI. The last criteria combined with very forgiving settings in a couple enviormental variable's is why in stock, you dont hear alot of pinging. In otherwords, It's not like they go around pinging randomly hoping to get a contact.

[Steeltrap]

Few comments:

1. Unbelievable that being on the bottom has no effect on your ability to be detected. While it certainly didn't (hence shouldn't) grant immunity to detection, lying on the bottom DID have an effect on how easy a U-boat was to detect based on...
- depth
- 'type' of bottom (rocky, sandy, cluttered - weeds, debris etc.)
- local conditions (current, presence of water-borne particulate matter)
Being near river estuaries, for example, would play merry hell with ASDIC due to different temperatures, salinity and debris in water.

2. The mod is a clever addition and DOES add uncertainty. I've run across (or they ran across me?) 2-3 DDs patrolling, slipped by them, then had them contact me again some hours later as they - presumably - head off on another leg of their search pattern. No more "right, got past them, end of problem!".

3. Stupid that AI doesn't use active regularly, as common doctrine was to run it always AFAIK. Sure, the escort will be detected, but then a U-boat will always hear an escort before the latter hears it, and the active means there is a real danger area around an escort, addin to its deterrance value.

4. Very interesting to hear about how the AI works with detection etc, and the pic from Ducimus is a beauty.

Having great fun with NYGM 2.2!

[Der Teddy Bar]

Though it does not show it in the pictures above, the number and areas that the escorts cover ramps up over the years.

For example Scapa Flow will not be a walk in the park but is achievable until the date of the original attack when the escorts are ramped up.

The same goes for various other coastal regions.

NYGM will be doing the BIE Mod for other regions such as Gibraltar, of course it would then be the GE Mod :D

The BIE Mod will be re-evaluated after more feedback from the WaW patrols and various forums.


It is great to hear the enjoyment that you are all getting out of the NYGM TW 2.2 Mod :up:

[SubConscious]

I had an interesting experience last night related to this thread, so I thought I'd resurrect it.

First, I should probably admit that I'm not using manual targeting yet. :oops:

Ok, so I received a wireless that a large convoy had been spotted heading east, just north of my position. On my way to intercept, I encountered a large merchant heading west. If you’ve ever tried to sink an 8000GRT outbound merchant with a deck gun, my advice is to not attempt it. It took forever to sink, but that’s another story.

I finally get into position ahead of the convoy and start assessing the situation. The conditions are just about perfect: November 1939, Winds 7 knots, light fog, about 1am. There is a Flower Corvette ahead of the convoy and a large Auxiliary warship in the center row of the convoy, bringing up the rear. I can’t see any other warships, so I take a quick dive to determine if my Sonarman can pick up anything. No other escorts were detected.

I then move to get ahead of the convoy, positioning myself so I can take out the medium tanker and large cargo ships at the center. The boat is running at 7 Knots, 1 Knot faster than the convoy, and with decks awash at 7 meters depth.

Wouldn’t you know it: The Flower Corvette spots me. It doesn’t light up its search lights yet, but it starts steaming right for me at 16 knots. It’s decision time, but I’m tired, as it’s 1am in real time as well. Rather than just exit the game and save the battle for tomorrow, I decide to try to take out the Flower Corvette in a running gun battle.

Yeah, I was pretty tired.

As I’m not using manual targeting, I was able to look thorough my periscope and determine the enemy was about 4000 meters away and closing fast. I respond by turning to face the enemy while ordering emergency reverse. My logic here is to minimize my profile to the enemy while maximizing the time I’ll have to fire.

The deck gun crew gets set up for a 3500 meter shot, but the boat is pitching wildly in the 7 Knot seas. I have found firing directly over the bow to be the most difficult for this reason. Still, I’m considering this the lesser of two evils (the other being presenting a juicy broadside to the Corvette’s cannons), so I try to time the shot so the barrel of the 88mm is just right and with the Corvette’s shells screaming overhead, I fired…

…and I hit him. Not just once, I nailed him 3-4 times in short succession (missing about 30% of the time).

This is the interesting point, and the reason for this post: The Flower Corvette, now at 2500 meters and closing fast, decides to turn away. No kidding – the escort turned completely around and started steaming directly away from me. Now wide awake, I order flank speed ahead to try to catch her. I’m still firing the 88mm deck gun like a madman and I can see that I’m scoring hits, as the Corvette is now burning both fore and aft. She makes a hard turn to port to bring her guns back into play when a final 88mm shell slams into her…

…and I receive the notice from my watch officer that “She’s going down!”

I couldn’t believe it. I had to pause to read the line several times just to make certain it wasn’t my imagination. My boat didn’t take any hits during the engagement, though there were a few near misses. Very, very lucky…

The really cool part of this encounter was when the Corvette turned away. I’m assuming that there was something added to the code to make them attempt to escape from a losing battle, though I suppose it could have been a fluke. Still, it was a LOT of fun, regardless of how silly the act was.

Oh, and by the way, with that Flower Corvette out of the way, my VIIB was like a fox in the henhouse. I ended up sinking that auxiliary warship, the medium tanker and two large cargos. Having run out of eels, I surfaced and spent my remaining 21 deck gun rounds on a medium cargo ship, which gave up the ghost after the final round found home. I guess it’s time to move to manual targeting, but I’m having a blast. ;)

[SubConscious]

I have been playing around a bit with Flower Corvettes and I think they need some help. It's actually very easy to sink them if you surface behind them and pound away with the deck gun. It's easy because they don't bother to try to turn to bring their forward deck gun into play - they continue on their current course. It's easy to take out the rear gunner, as the poor fellow is virtually unprotected. The forward gunners then just shoot into the water to either side, as if they're trying to engage the enemy, but the ship can't maneuver. I've tried this in four tests and the result was the same.

I find this interesting in that if a Flower Corvette spots me on the surface, it comes right in for the kill. Similarly, if I surface in front of the ship, it blasts away (albeit rather inaccurately). Surfacing behind them appears to really throw the escort logic for a loop.

I suppose there is some possibility that my first round takes out steerage, as I first try to take out that rear machine gunner and searchlight, but I think this is unlikely.

Has anyone else experienced this? Is it just a fluke?

[Der Teddy Bar]

I have been playing around a bit with Flower Corvettes and I think they need some help. It's actually very easy to sink them if you surface behind them and pound away with the deck gun. It's easy because they don't bother to try to turn to bring their forward deck gun into play - they continue on their current course. It's easy to take out the rear gunner, as the poor fellow is virtually unprotected. The forward gunners then just shoot into the water to either side, as if they're trying to engage the enemy, but the ship can't maneuver. I've tried this in four tests and the result was the same.

I find this interesting in that if a Flower Corvette spots me on the surface, it comes right in for the kill. Similarly, if I surface in front of the ship, it blasts away (albeit rather inaccurately). Surfacing behind them appears to really throw the escort logic for a loop.

I suppose there is some possibility that my first round takes out steerage, as I first try to take out that rear machine gunner and searchlight, but I think this is unlikely.

Has anyone else experienced this? Is it just a fluke?
Thanks for the feedback. We will look into this and see what we can do.

[SubConscious]

Thanks for the feedback. We will look into this and see what we can do.

I'll try it again later tonight (after the munchkin goes to bed) and see if I get the same results. Four incidents aren't a very good sample to work with. It could just be the luck of the draw.

Thanks for your responsiveness and willingness to explore this issue. :up:

[SubConscious]

Addendum: I tried this again tonight against two separate Flower Corvettes and had the same results. In each case I surfaced aft of the corvette and opened fire with my deck gun. The corvettes made no attempt to maneuver, though they did engage me with their stern weapons (while they lasted). One of the corvettes had started to turn to port just as I surfaced - it continued at the same very slight rudder position it began with and it was therefore very easy to remain astern of this vessel.

I encountered similar behavior from a Black Swan Frigate. I had hit the frigate with a lucky magnetic pistol torpedo shot that detonated under its bow gun emplacements (a testimony to the iron steadfastness of the Royal Navy sailors: These men stayed right at their posts despite being on fire). When I surfaced to engage each corvette, the frigate maintained a course away from me while firing with its aft weapons.

I'm wondering now if there isn't something in the escort logic that tells them to move away once they're damaged, or damaged to a certain point. If you read my previous post (about 2-3 up), you'll see I encountered the same situation earlier. For that matter, this logic might be built into all computer-controlled ships.

I suppose the next test would be to surface behind a Flower Corvette while holding fire, to see if the corvette turns to bring its larger fore deck gun to bear. Any takers? ;)

One last bit of information: It appears that the deck gun is not affected by wave action when it is oriented to fire directly over the bow. I tested this tonight by firing at a large cargo ship. No matter whether the bow was up, down, or level, my shots hit in the same place. In retrospect, this is probably why I was able to hit that Flower Corvette from 3500 meters out in 7 knot seas at speed - I was firing over the bow each time.

It is my sincere hope that this information is coming across as collegial constructive criticism rather than as complaints. I'm having a great time playing NYGM 2.2!

Oh, and by the way, kudos to whoever did the enhanced pyrotechnics. Just before exiting the game, I decided to see if I could hit that fleeing Black Swan Frigate with a magnetic pistol torpedo from dead astern at about 3600 meters. Lucky shot again (very lucky), and I was rewarded with a series of beautiful explosions and fireballs. Absolutely stunning - I wish I had recorded it! :up: