SUBSIM Radio Room Forums - View Single Post - Sonar experts: How much sound crosses a layer?

OKO · 11-26-05, 07:07 PM

sure Amizaur : my graph wasn't very accurate, it was just an example.
But personnal experience abord sailing ships and my love for physics (even if I'm not a physicina myself) just show me there is real gaps in this matter
For example, on my ship, well ... my father ship, a catana of 44ft, I could see it's quite easy to go to 10 knts, even with low wind speed (15 or 17 knts), without near any perturbations at the tail of the ship, and the perturbations will start around 11 to 12 knts.
From that speed, we really need more wind to get over this gap (our personnal best speed is 21.3knts on this boat, with 40/45 knts of wind "au portant" and the smallest sail)
It's simply due to the hull shape.

I'm convinced there is some gap also for sub hulls.
Because they are also subject to physical laws.
So, gap changing drastically the noise generated.
There is a before and after the gap
after the gap, water perturbations start and make much more noise than the noise generated by the sub itself.
This gap is not modelised at this time
and this is domageable for tactics.
because I'm convinced a good commander of a real sub KNOW this gap and know when he can go over this or when he can't, because he will risk counter-detection

This gap should be VERY different, depending on sub tech
Well all read Akula is as quiet as US subs AT LOW SPEED and NOT on high speed.
I think it's just because this gap is reached earlier with the Akula than with a 688i and furthermore with the Seawolf.

Seawolf is known to be "silent until 20 knts"
20knts is his gap, before he is really stealthy, after he make much more noise.
I think this gap should be around 12 or 14 knts for 688i, and beetween 8 to 10 knts with Akula.
At this time this isn't modelised at all
We have a progressive and linear curve that doesnt' reflect this kind of real problems.

Of course, these data should be one of the most secret ones.
But with some talk and tought, we could find something much closer to the real thing than what we have actually.
I'm still convinced the original data were closer to the real thing than what we have from the sound vs speed fix ... or with the LWAMI.

11-26-05, 07:07 PM	#2
OKO Commander Join Date: Jan 2002 Location: Solar system, mainly on earth Posts: 476 Downloads: 62 Uploads: 0	sure Amizaur : my graph wasn't very accurate, it was just an example. But personnal experience abord sailing ships and my love for physics (even if I'm not a physicina myself) just show me there is real gaps in this matter For example, on my ship, well ... my father ship, a catana of 44ft, I could see it's quite easy to go to 10 knts, even with low wind speed (15 or 17 knts), without near any perturbations at the tail of the ship, and the perturbations will start around 11 to 12 knts. From that speed, we really need more wind to get over this gap (our personnal best speed is 21.3knts on this boat, with 40/45 knts of wind "au portant" and the smallest sail) It's simply due to the hull shape. I'm convinced there is some gap also for sub hulls. Because they are also subject to physical laws. So, gap changing drastically the noise generated. There is a before and after the gap after the gap, water perturbations start and make much more noise than the noise generated by the sub itself. This gap is not modelised at this time and this is domageable for tactics. because I'm convinced a good commander of a real sub KNOW this gap and know when he can go over this or when he can't, because he will risk counter-detection This gap should be VERY different, depending on sub tech Well all read Akula is as quiet as US subs AT LOW SPEED and NOT on high speed. I think it's just because this gap is reached earlier with the Akula than with a 688i and furthermore with the Seawolf. Seawolf is known to be "silent until 20 knts" 20knts is his gap, before he is really stealthy, after he make much more noise. I think this gap should be around 12 or 14 knts for 688i, and beetween 8 to 10 knts with Akula. At this time this isn't modelised at all We have a progressive and linear curve that doesnt' reflect this kind of real problems. Of course, these data should be one of the most secret ones. But with some talk and tought, we could find something much closer to the real thing than what we have actually. I'm still convinced the original data were closer to the real thing than what we have from the sound vs speed fix ... or with the LWAMI.