It's been a while until I could get directed to a convoy in daylight. Finally, got an intell report on a convoy transiting the Formosa Straits and camped there for two days until I intercepted them from their stbd quarter. Went to flank and ran down their stbd flank until 10nm ahead then went to RD at 10nm in the early afternoon. Went to PD at 7nm.

Seas were slightly lower than above, 8-10ft. Water depth was 68ft!

It was a sixteen ship convoy (4x4) w/ seven escorts mostly Type D coastal defense corvettes plus an Akikaze on the port quarter. My intended tactic was to penetrate between the lead and stbd wing escorts. However, as often occurs, this didn't work out; the convoy altered course to port which put us dead ahead of the stbd wing escort. We kept the lead escort pointed and he CPA'd us at 3600yds right on our bow. Escorts were not patrolling, but on point stations doing same course/spd as the convoy, southerly at 9kts. At this point the lead escort had ceased to be a problem, but the stbd wing corvette was on our port beam at 2200yds, target angle 330; so she became the immediate threat.

We abandoned the idea of splitting the two and concentrated on showing minimum aspect to the stbd wing corvette. We put the rudder over hard right and tried to get and keep her directly astern. By constantly adjusting the rudder angle this worked until we were past CPA on her stbd beam at 900yds with her at our 180. So we essentially ended around her by stern pointing.

Periscope was up altho just barely the whole time and not detected.

So this wasn't exactly what I was looking for; seas were still too high; I really wanted calmer conditions. So will keep testing.

I'm satisfied that the lead escort didn't detect with a CPA of 3500 yds regardless of aspect altho we held her directly on our bow so no way she detects. I'm ambivalent about the stbd wing corvette. Yes, we kept her pointed astern from 2200yds inward. And astern pointing is actually more effective than bow pointing because of the acoustic interference of the sub's wake. I'm not sure that TMO/SH4 takes this into consideration. I would not have been surprised to be detected in this instance and am not surprised not to have been.

In the real world today, the sub would be almost undetectable in water this shallow except by aircraft. Our mostly lower frequency sonars are optimized for long range open ocean detections. In shallow water, the bottom reverberations just kill you; you can't distinguish the sub from the echo returns from the bottom. The Brits have actually figured this out better than we have and often emplace two sonars on their escorts, one long range and one higher freq for shallower conditions. I can't imagine that the game cares tho.

Sniper, my experience w/ across layer ranges is that below layer ranges are no better than 25-33% of above layer ranges. Does that square w/ your numbers?

Hard to say, at 60 I'm too senile to keep track, and math was never my strong point. If I'm reading the comments in the file correctly, 1 equals no signal loss, 5 is 20% as in 80% loss, 3 is 33% as in 66% loss. I'd try to extrapolate all that if I could remember how, but basically the lower the number the less loss of signal therefore 1 = easy for them to hear you, 5 = hard for them to hear you.

As for shallow water, unless I'm in a harbor I try to shadow a convoy or task force that's heading into deeper water rather than attack in the shallows. My real life experience with water less than 100 feet is passive sonar was only affected if there were a lot of shrimp or something on the bottom making noise, active sonar was hopeless with all the reverb.

Wake turbulence I dunno, but bow masking was something that shocked the hell out of me when I first experienced it. Sonar station in the SH-3D was about 10 feet aft of the pilots on the starboard side, two seats with a passageway to port, small square window next to the outboard seat. I was sitting in the inboard seat one day listening with the transducer down at 250 feet, and the AW looks out the window and says "Here comes the Forrestal". I leaned over to look, and sure enough she's coming straight at us less than 2 miles away, I never heard a thing until she turned and unmasked the screws. Never realized until that day that there was a dead zone directly in front of a ship which blocks all the noise from the screws, either they didn't mention it in ASW school or I slept through it. On advice of counsel I decline to say which is more likely. :up:

Please, "suggested hack" : ) - taken from my notes of a conversation with someone(??) .... we were discussing night surface attacks, specifically Gene Fluckey's method of night surface attack that is quoted in this excerpt on Tom Martin's site:
http://www.cs.cmu.edu/~tlm/silent/barb_report.html
..... and frustration that this method I used numerous times in SH1 SHCE wasn't possible in SH4 using the stock or mega-mod settings.

Fluckey used this method in real life and it is fun to successfully use it under the right conditions in SH4 - or - SH1 SHCE (pick your poison)

Years ago as soon as I read it I had to try it, and I used it many times. Great fun.

This thread is good, I've been following neilbyrne's updates with great interest : ) Thank you.

Happy Hunting!

It is to bad there is not a mod to reduce sonar signals from AIs to the boat when under layers. It reduces the signal to the boat but in the game it doesn't model that.

My friends,

Seas have remained high; TROUT was down to five torpedoes. So I sank some single sailers and am back in Guam rearming. Then back to testing in calmer waters hopefully.

I loaded these values and I am happy to say that I think they are much better than the original values ! We now have a fighting chance against the IMJ Navy late in the war. Thank you aanker for sharing this information with all of us.:salute::salute::salute:

Also I want to add that was able to intercept a fast convoy of troop ships - 2 Conte Verdes & 2 Horai Marus with a 4 ship screen of destroyers in calm water conditions at night in the Formosa Straits. I got all troop ships then evaded the area without being detected by the escorts !:arrgh!:

Isn't it a shame there are no mods that simulate the Phosphorus glow in some waters around the world. You wouldn't believe how a scope above water gets lit up when there is Phosphorus present.

When you are talking about scope detection there are so many factors that influence how far away it can be seen at night and during the day.

Haze, moon light, time of day or night, chemical composition of the water, speed, waves, mens eye sight, optics used ... all are factors when trying to observe at sea ... many just do not think about them or know about them.

When you have been there ... you remember. :Kaleun_Salute:

Like this beach is lit up with them... I stole this from Subsim's Facebook to post here:

http://i127.photobucket.com/albums/p...ps526a4ea3.jpg

Still, the ASW should not be detecting submarines like they do in SH4 from miles away when the boat is running Silent @ 2 kts and presenting a small profile.

Furthermore I have read 100's of night periscope attacks, and many night surface attacks from real WW II reports that are impossible to duplicate without messing with the files in SH4.

Thank you bandit484 - glad I could help.

Happy Hunting!

Testing with a sugar boat (best use of that, drive your 12 torpedoes at 12 knots to the deepest part of the South China Sea, scuttle the leaky rattletrap and head for Groton to get a real sub!:har: ) fired all four (weakassed slowpoke mark 10) bow tubes, stopped a battlewagon dead in the water. Gotta wait for the tubes to reload but attracted the attention of some patrolling cans.

https://scontent-b-ord.xx.fbcdn.net/...43679601_n.jpg

Shallow water, no layer to hide under, but here's a good spot;

https://fbcdn-sphotos-a-a.akamaihd.n...86215207_n.jpg

They know where I am, but can't touch me. :arrgh!: So after reloading all four I sank the cans one at a time, then finished off the BB. :salute:

LOL ... I hid like that once ... until it sank on top of me and crushed us.



If anyone wishes to read the words of the Captain ... there are plenty of war reports here:


http://www.hnsa.org/doc/subreports.htm

I've hid under ships many times, one time near Savo under a dead in the water Kongo. I had several DD's trying to get to me, but was safe. I had cams off, so used the periscope to get there. I then heard bombs going off and took a peek with scope coming up near the ship, US planes were bombing it....It took many hits and it crossed my mind if it exploded I would die...so I took off to chance it. They finally got a hit and it exploded and blew me up..

It can be hazardous in deep water, I once ran a Gato at full tilt boogie under a sinking cruiser to get away from a pursuing tin can. The can rammed the cruiser and made it roll over and go down like an express elevator with me tangled in the superstructure, blowing tanks and back emergency I managed to get out from underneath at 800 feet.

Which of course wrecked everything on board, even after getting back up to a reasonable depth there was no saving it after that.

At last I got a tactical situation I wanted to test against. The target was a four ship convoy, all medium to large cargo ships in two columns seperated by 700yds. There were five escorts, all corvettes except for one MINEKAZE (on the convoy's port bow) and all equipped with radar. Convoy speed was 8kts; escorts patrolling at 10.5kts.

Environmentals were perfect; weather clear in broad daylight with seas at 1-2ft, thermal layer at 165ft; water depth 1,000+.

I did five runs. In all cases went to RD with the lead escort at 13nm and went to PD with her at 5.9nm. Was never detected on radar which is realistic. The USN purpose built surface search radar at the time, the Sugar George or SG, had a reliable range when mounted on a destroyer of 8nm vs. another DD. So catching a surfaced sub, bow on at 13nm not happening.

I left about two feet of scope up constantly in all runs and stayed at 2kts throughout.

Run #1. I planned to approach from just off the convoy's bow to stbd, keeping the lead escort pointed and shoot the lead ship in the stbd column before the stbd wing escort could detect. We CPA'd the lead escort bearing 020 at 1600yds target angle 090. Once in her baffles, we came around perpendicular to the convoy's track and put one fish into the lead freighter in the far column and three into the near lead sinking her. I hung around admiring my work for too long and the stbd wing and tail end corvettes both detected at around 1400yds and we had to run for our lives.

Run #2. In this approach we made no attempt to point the lead corvette, showing her a beam to test. The stbd wing corvette was not patrolling but on a point station off the convoy's beam. The lead escort was patrolling off the convoy's port bow and we CPA'd her bearing 090, range 2700yds, target angle 135. No detection which is believeable. We then went hard right rudder to deliberately present the stbd wing corvette with a beam aspect to see when she'd detect. She started pinging at 1800yds and got contact at 1650yds which is nothing to bitch about.

Run#3. Same approach as #2. CPA'd the lead corvette at 2050yds on our stbd beam, target angle 130, no detection, fine, could have gone either way, but with this layer condition I'd say it's realistic. Remember, the max detection range of these sonars is 2000-2500yds in wonderful conditions, isothermal to 400ft. With the layer at 165ft, you'd be lucky to get half that. The stbd wing corvette detected on our port beam at 1350yds and the tail-ender at 1300 from dead astern. No problem.

Run #4. Here I wanted to see if the MINEKAZE could detect better than the corvettes. So after going to PD, put the convoy on our port beam with the intent of crossing ahead, keeping the lead corvette pointed and present a beam to the MINEKAZE. Didn't work out that way. The leader detected us at 800yds directly on our bow. No problem.

Run #5. Same attempt as #4. This time it worked and we CPA'd the lead corvette bearing 180 at 1800yds target angle 270, no detection, again could have gone either way. With the leader now past CPA and opening, we kept her directly astern while presenting a beam to the MINEKAZE. When she was bearing 280 range 2450yds, target angle 020, she started pinging and flashing "contact detected". This range is long for a layer depth of 165ft, but given all the closer detections in the runs above, I think the random number generator just pulled a great number for the IJN in this case. So in the odd case, it's acceptable given the above averages are about right otherwise. Once in a while a hotshot will detect at better than predicted range, but the average needs to fall into acceptable parameters which in the above cases it did.

So overall, I'm pretty satisfied with these numbers.

Spider, I'm curious as to what you're seeing for detection ranges since you made your changes?

I'm wondering where I can change the passive sonar settings in these values, I see where I can change the active sonar (red line) but not the passive.
Could someone please tell me which line is passive sonar?

[Visual]
Detection time=2 ;[s] ;was 0.5
Sensitivity=0.01 ;(0..1)
Fog factor=1.25 ;[>=0]
Light factor=2.8 ;[>=0] ;was 2.0
Waves factor=1.0 ;[>=0]
Enemy surface factor=350 ;[m2]
Enemy speed factor=15 ;[kt]

[Radar]
Detection time=1 ;[s]
Sensitivity=0.01 ;(0..1)
Waves factor=0.9 ;[>=0]
Enemy surface factor=5.0 ;[m2]

[Hydrophone]
Detection time=10 ;[s] ;was 1
Sensitivity=0.01 ;(0..1) ;was 0.04
Height factor=0 ;[m]
Waves factor=0.55 ;[>=0] ;was 0.75
Speed factor=15 ;[kt] ;was 20
Noise factor=0.2 ;[>=0] ;was 0.5

[Sonar]
Detection time=15 ;[s] ;was 10
Sensitivity=0.005 ;(0..1) ;was 0.01
Waves factor=0.6 ;[>=0]
Speed factor=15 ;[kt]
Enemy surface factor=100 ;[m2]
Lose time=30 ;[s]