Are hull expansion and plane hydraulic noise modeled?
 

I read on reddit's /r/coldwaters that transients from angling dive planes and from the expansion and contraction of the hull when rapidly changing depth actually generate noise in-game and can lead to your being counter-detected. Is this true? If so, how do you minimize it? I'm wondering if this is why I seem to be counter-detected by certain surface ships and submarines in the 1984 campaign within minutes of starting a mission game regardless of how far away I start or how fast I am going, even on casual difficulty.

A while back one of the KillerFish crew was on Jive Talk with Jive turkey and patreons and he commented that they are aware of bug that has people getting detected as soon as entering a mission (unintentional). If this is the case, we have to deal with it until next patch.

Also, my understanding is start distance to your mission contact (25, 15, 10k yrds), the sub you're using, are factors as well as your speed if/when detected and possibly over head flights by ASW air craft and/or satellites could potentially play into your initial detection.

As for hull popping/hydralics, I haven't heard that this is a noise factor, though seeing as we can hear ships breaking up, I would not be surprised if sudden depth changes shallow or deep would play into your noise signature. It would be closer to reality, anyhow.

my guess is that "breakup noises" in game are just the sonar picking up a contact that the game identifies as destroyed. The sonar isn't actually picking up the ship's death throes.

Thanks for this info.

Unintentional? LOL. I make it a habit to peruse the forums of games I MIGHT be considering purchasing and this is the type of info that puts me into "purchase freeze" mode.

Maybe next year after several patches and bargain bin Steam sale prices.

Still well worth purchasing IMHO. I bought on release and the devs are a cut well above the rest of the game developers. I'm pretty sure it will be addressed soon.

In real life, hull compression and expansion when changing depth makes minimal noise and isn't a classification cue unless you're in a (very) close trail, which causes an acoustic phenomena called Near Field Effect.

Transients from plane movement can occur, depending on the boat, but aren't common. We spent two months with fairwater planes that not only sounded like biologics every time they moved, but occasionally set off the torpedo detector, due to the many frequencies produced. We couldn't get that repaired soon enough!

This is interesting because 'older boats', say Skipjacks and Permits had issues. So in a battle of new vs old, it could be problem. Jive Turkey had the SJ out was reporting "explosions' as he cruise 700 ft before leveling out and the RBU's started dropping. It would probably be unique on a boat basis, and its duty/maintenance cycle. I suspect it's just averaged into a boat's self-noise. Some are quiet and some aren't.

It doesn't seem 100% consistent to me. I didn't seem to have the issue in the '68 campaign, but it happened often enough in the '84 campaign that I just never hit the "close to" button. Sometimes this gives me enough distance, sometimes not.

I actually thought this was fixed. I used to get this bug when the game launched - I have the distance scale set to 1:1 and always go to battle stations rather than close to a distance.
I was getting instantly detected nearly every time and couldn't figure out why, then one day it just stopped and everything seemed to be normal.

But like I say, this was way back right after release.