Frustration with destroyers

[DarkFire]

I'll apologise in advance if this question, or similar, as been asked 10,000 times in the past. I'm playing the stock though patched SH4 at 0% realism. I know, I know, but I'm used to firing guided missiles at subs, not skippering one

Anyway, having eventually got through most of the tutorials I thought it would be time to take on a single mission. I forget the name of the one I chose, but it's the one where you have to sneak in to the harbour & take some intel photos. It appears that two DDs are patrolling the entrance to the harbour. In this mission I was skippering (in the loosest sense of the word!) a Salmon (the USS Salmon?)

My plan was to submerge long before I got within range of the DDs - about 15000 yards off my bow - go deep, rig for silent running and creep by. I took her down to 120 feet as I wasn't and am not sure what the crush depth is for the Salmon, ordered battle stations and silent running. Passive sonar seemed to indicate no course change by the DDs so after a few minutes I ordered ahead 1/3 and waited. I was doing perhaps 4 knots submerged at that point.

As soon as I got within probably 8-9000 yards of the DDs they homed in on me like omniscient death machines. Very soon I was being pinged by active sonar. A few depth charges later and the Salmon was no more

So here's my question - how did the DDs detect me so far away at that depth and how did they manage to be so accurate with their depth charges?

Also, could I have gone much deeper? Does stock SH4 model thermoclines? Or is that area of the pacific isothermic down to the crush depths of most WW2 boats?

Can anyone offer a bit of advice?

[Platapus]

Welcome aboard!

First the test depth of the Salmon was about 250 feet, probably deeper than the harbour.

Second what was your approach path? Were you taking advantage of the terrain? Trying to sneak down the center of a channel is not always the best. In some cases it may be better to sacrifice depth for getting a little closer to the shore.

Third, always try to keep either your bow or stern pointed at the destroyers. The "thinner" your aspect to them the harder it is for them to detect you.

Fourth, 4 knots is a bit fast. At 1/3 speed you may have popped out of silent running. Try getting down to 1 knot.

Fifth, when sneaking past DDs, try to figure out that pattern of their patrol and identify a time when both are looking the other way. Subsims are a stealth game. You are going to spend most of your time waiting and watching.

Is there anything in your orders that say you can't sink the destroyers? I am being serious. At periscope depth you are actually harder to detect on active sonar. Maybe consider a night approach and create a "distraction"?

If the DDs are picking you up at 8,000 yards, you are broadcasting something.

Good luck with it and welcome aboard

[Hinrich Schwab]

I agree with Platypus that you had to have done something to give your position away at ~8000 yards and anything over 2 knots on silent is risky. However, I have observed that the stock AI in SH4 is a bit...fruity. I have seen the omniscient moments you have spoken of (mainly in avoiding torpedoes) while also seeing destroyers act dumber than Lumpy from Happy Tree Friends. Without more details of your approach, it will be hard to say what went wrong.

The game does take thermoclines into account, but not in a realistic fashion. If I remember the older posts that address this, the game simulates thermoclines by altering the range of the sonar on each destroyer.

[Rockin Robbins]

Welcome to Subsim! Love to see new players and I remember the frustrations.

Just a couple of pointers, some of which are already covered.

• Keep aware of sea conditions. Smooth seas are big trouble for you. Rough seas are noisy, making you harder to detect on sonar and help keep your visibility down.
• Darkness, fog and rainfall are your friends. Whenever I am attacking multiple targets or avoiding multiple foes I use these. Especially with darkness, it's at your disposal every day.
• When you hit the "z" key or push the silent running button your sub automatically slows down to a suitable speed. Often, on silent running I go to control room view, move to the tachometers, to the right of the ladder to your right, and tweak the speed to 100 RPM. This is a surprisingly fast 3 knots and is extremely stealthy, even in TMO, one of the mods that give the enemy more teeth and claws.
• Already covered in part, but time your entrance when patrol boats are moving away from the entrance. They have a sonar "hole" in their baffles, about 20º both ways from their 180º bearing, where their motor and screw sounds mask your presence. Have patience and pick your spot.
• I also agree with going in at periscope depth. Awareness is worth even more than stealth. The more you know about the enemy, the better you can avoid them.

These harbor penetration deals are nasty. They are also inaccurate, as very few harbor penetrations were made in the war. You must give up many of the advantages a submarine brings in order to do a harbor penetration.

Have fun!

[DarkFire]

Well, thanks for all the information, I'll get back to work...

I didn't know it was possible to adjust the boat's settings directly from the instruments in the control room - 100rpm makes sense though as I imagine it's actually the engine sound rather than hull drag noise that's detected by enemy passive sonar sets. Very useful to know. I also didn't realise that SH4 models the noise of sea states. Again very handy for the patient skipper

Am I right in thinking that the gramaphone and radio can also be turned off from the control room? If they radiate noise then I'll turn 'em off as well. I'm guessing that WW2 ships don't have passive radar receivers? Will I be safe in operating my surface radar until I submerge to periscope depth?

Hmm. It seems that I have a LOT of learning to do. My dreams of single-handedly taking on the Yamoto will have to be put on hold

Thanks again. It's nice to be able to come here to learn from the experts!

[Platapus]

I am not sure that the noise of the record player/radio is actually modeled in the game in such a way to give your position away.

Anyone know fer sure?

[Rockin Robbins]

I'm quite sure they are detectable, but I've never tried it myself to check it out.

[VoodooPriest]

Hello Subsim. Haven't been here in a while.

Anyway, I got me SH4 a while back and started playing it.
And now I have almost the same question about DDs as the OP. I was tasked with taking photos in Tokyo harbour. I went to the bay entrance and arrived there at dawn, so i decided to wait out the day submerged and sneak in in darkness. I dived to 75 meters under a thermal, stopped the engine, set silent running and waited. After about 4 hours sonar picked up a warship, so I reduced TC an watched what he would do. He came to my position in a straight line, dropped everything he had and managed to hit me with 2 DCs! Then he turned around, pinged me once, again dropped a full load and again hit me with several DCs. And did it again and again.
So i quit the game and came here right away to ask if that's normal behaviour in SH4? How could that ship even know i was there?
I'm playing 1.5 with only the realistic optics mod.

[I'm goin' down]

Originally Posted by Rockin Robbins

I'm quite sure they are detectable, but I've never tried it myself to check it out.

I deleted the post that said to turn on the radio by mistake. That is what the post above referred to.

I respond to Double R as follows:

A couple of years ago, someone brought it up and was advised that the dds AI could pick up radio sounds. That is why I entered the post, which I mistakenly deleted, advising to turn off the sound.

[Rockin Robbins]

I'm saying that you're right and destroyers can hear your radio and gramophone. I just don't have first-hand evidence to prove it. I have heard it from usually very reliable sources. I think I may set up a mission and check it out.

Maybe I'll even check it out in my TMO career and reload if I get killed doing it! My money says it's death for sure.

[Elder-Pirate]

Will you please hurry up with that radio/music test RR. I'm on a run from Freemantle to Singapore Nov. 14th 1944 for a photog of some enemy ships. I'm about 48 NM East from Singapore right now, 2PM and sitting on the bottom in 175 ft. of water in the USS Pilot Fish ( Balao ) waiting for dark. Hiding on the bottom because two DD's ( Shiratsuyu I think ) are about 8,500/10,000 yds. patrolling the area.

Waters are very shallow anywhere in the Singapore area.
My guys aren't gonna be happy if I tell them NO MUSIC after surfacing.

I'm running stock ver. 1.5 with a bunch of mods.

Good to see your posts again RR. I've been gone ( off this site ) for about a year and a half.

[Rockin Robbins]

Good to see you too, Elder! I had some computer problems last night but will be getting down to business today. I'm going to violate my principles, save the game and do this in-campaign, then restore at the save point no matter what the result.

So we'll be talking about October/November 1942 in the Slot. I here there were some destroyers there....... So it'll be a good test.

[Daniel Prates]

Originally Posted by DarkFire

As soon as I got within probably 8-9000 yards of the DDs they homed in on me like omniscient death machines. Very soon I was being pinged by active sonar. A few depth charges later and the Salmon was no more

Don't forget that in some situations, your scope can be seen from very far away. If the seas are dead calm, if there is good visibility, if yoiu have high underwater speed, well, then your scope will leave a big enough wake to be seen.

[Daniel Prates]

So when you are creeping in the manner you were, you are supposed to take small peaks - no more then seconds - and if not, you get good chances of being spoted. This, of course, is less probable during the night, or during bad weather.

[VoodooPriest]

Originally Posted by Daniel Prates

Don't forget that in some situations, your scope can be seen from very far away. If the seas are dead calm, if there is good visibility, if yoiu have high underwater speed, well, then your scope will leave a big enough wake to be seen.

I for one was, as i said, at 75 meters (245 ft), on silent running, engines stopped, for 4 hours. That sub hunter came right at me in a straight line, without even searching for me and hit me in his first attack run. He knew exactly where I was. And I had no grammophone or radio on, as I don't like music while playing. Very strange incident.