So are the hydrophones supposed to work on the surface?
 

I've been reading both yes and no answers on this forum. I have been in porpoise, salmon, and Tambor classes and they havent been working on the surface for me. Just want to know what is realistic and a definitive answer.

The time dilation glitch thingy kinda gives away when you are supposed to dive to do a sound check. If in fact the hydros aren't supposed to work on the surface that is.....

Unfortunately I'm not one of the board experts
 

My understanding is the following: the hydrophones are on the bottom of the boat, therefore they are deep enough under water to also work when surfaced. However so close to the disturbance of the waves, you cannot hear the fainter sounds of more remote ships. Therefore - apart from thermal layers of course - the effective range increases when you dive and get more distance between you and the waves. This effect decreases though, because at some depth the waves are just far away enough to not cause any more disruption. In a storm where the waves are higher than the boat the hydrophones would probably be useless on the surface but submerged have a much better range than spotting and probably even early radar on the surface.

How it is implemented in the game I have no idea however.

The boat has three passive listening devices.

One on the top of the deck ... that is the JP sonic passive hydrophone. JP is the Navy term for sonic listening gear. The J means that it can be used for listening only. The second letter P merely indicates the model.
Sonic gear is useful for picking up targets at great distances because sonic sounds travel farther. Also, on the JP gear sounds appear more natural and are more easily recognized. Therefore, you can identify not only the machinery noises of enemy ships, but also any telltale noises your own submarine is making.


There are two supersonic hydrophones under the boat in shafts that make them retractable.

Supersonic gear picks up sounds too high for the human ear to hear and changes them into sounds which can be heard.

JK/QC is the Navy term for one type of supersonic gear. The JK half of the combination projector is for listening only; the QC half can also be used for sending out sounds into the water.

QB designates the other type. As indicated by the letter Q, the QB projector can send as well as receive sounds.

Supersonic gear is useful for picking up the important supersonic noises that sonic cannot get. Supersonic gear is especially superior for catching the bursts of supersonic sound used by enemy escort vessels in searching for our submarines. (In addition, QB and QC gear can be used to send out sounds into the water to determine the range of an enemy ship.)

It consists of three main divisions: QB, JK/QC, and NM. The QB projector is a spherical hydrophone mounted on the lower end of the starboard training shaft. One face contains rochelle salt crystals, which change shape when a sound wave strikes this face of the projector. The other side is empty.

The JK/QC combination projector is mounted portside. The JK face is just like QB. The QC face contains small nickel tubes, which change size when a sound wave strikes this face. The NM Projector looks some thing like a small steel coffin. It is bolted flush with the bottom of the submarine in the forward trim tank. The NM projector gets the current needed to send out pings from the same driver that is used with the. QC system.

When a submarine is running submerged, normally two men are on sonar watch. One is on the JP in the forward torpedo room. The other is at the WCA stack in the conning tower. The conning officer is at the periscope.

from:

NavPers 16167
Produced for ComSubLant by Standards and Curriculum Division Training, Bureau of Naval Personnel. Submarine Sonar Operator's Manual
June 1944
CONFIDENTIAL

===============

Chapter 5, page 38

"When your submarine surfaces, you will continue searching. While it is running at a slow speed, you will be able to listen efficiently."


http://www.hnsa.org/doc/fleetsub/sonar/index.htm

In the book, U.S. Submarines Through 1945: An Illustrated Design History, By Norman Friedman, page 198 states:

"Only in 1940-1941 did the U.S. Navy encounter British thin-steel domes, which made it possible to operate at about 15 kts."

This made it possible to use passive sonar to 15 kts.

By 1945 a single capital or merchant could be detected at 10,000 yards, a convoy at 15,000 and escorted capital ships at 20,000 yards.

This makes the idea of mods reducing passive sonar levels unrealistic.
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So is that a yes or a no? :oops: I'm playing in late 41 and early 42 at the moment in the classes I stated above. I don't seem to hear anything on the surface. Not even my own engines.

It's a yes.

In SH4 there is a full explanation in the TMO manual of how it works in the game.

JP sonic passive listening gear.
Available from January 1943
Max Range 15,000 yards

In SH4 JP is used in conjunction with WCA
Detection Range 15,000 yards submerged 10,000 yards surfaced.

One caveat; the programming for the game is designed to use one sensor and one sensor only at a time. So if you're on the surface in clear visibility and the lookouts can SEE the target, the sound man cannot HEAR the target. Foggy weather you're more likely to get a sound contact because the deck watch can't see it. The whole thing is completely screwed up, but if you're playing with map contact updates on, you should be able to see the blue or black lines indicating a sound contact up to 10 miles away. On the sonar station itself if you rotate the indicator the green lamp should light up and you'll hear the propeller noise within 10 degrees of the bearing, if the target is moving at 5 knots or better. A stationary target or one creeping along at 1 knot (the small troopship "task force" does that a lot) won't show a green light or make any sound, or show bearing lines on the map.

BTW this is stock SH4 1.4 I'm talking about, I have no idea what was changed in various gameplay mods, depending on what mods you have installed and in what order the sonar might not work the same way.

Supposed too?? Yes but not all mods model the sonar correctly.

Yeah I'm playing Real Fleet Boat and I have yet to hear anything while on the surface. Not even my own engines. Real fleet boat doesn't do map contact bearing lines either.

I wont use a mod that adds those contact bearing lines. I draw them myself if I really need them but mostly it isnt to hard to determine the enemy course if you simply steer towards them for a while.

I play with TMO on a Salmon class boat and i can hear on the surface.Also i cannot hear any stationary ship (like a destroyer that stops completely to hear better) even if it is very close to me and no green light indicator.

That's the way it's supposed to work, if it's making any kind of noise you should be able to hear it IF you have the indicator pointing to that bearing. Possibly the OP isn't rotating the pointer? Modern sonar hydrophones are omnidirectional and use a 360 degree PPI scope that shows blips where the noise is coming from, but WWII hydrophones were unidirectional and didn't pick up any sound unless it was pointed in that direction. You can click a button that orders the sound man to report contacts and he will rotate the dial all around and report any contact he hears - IF the contact is out of sight. In other words if it's visible to the deck watch or in the periscope he will not report it since it's a visual contact which doesn't qualify as a sound contact. Again, one sensor at a time per target is how the game is programmed, silly but that's how it works. You can still hear it if you operate the set yourself, but you do have to OPERATE it, as in move the pointer around the dial. The AI in this game is almost as bad as RailWorks.

On a submarine even water lapping at the hull of a destroyer could be heard. Things are not modeled perfectly in silent hunter but for the most part the mods do a great job of adding the realism to it.

This is a list of sounds from:
NAVPERS 11730RB: Recognition Drill

1. Waves slapping on hull of surface ship; 2. Fathometer of surface ship; 3. Acoustic minesweeper; 4. Foxer; 5. Snapping shrimp; 6. Porpoise; 7. Croakers; 8. Drumfish; 9. Garibaldi; 10. Surf noise,11. Bell buoy

This file can be found here:

http://www.maritime.org/sound/jp/11730rb.mp3

You'll find a good list of sonar training audio files as well as recognition files and submarine action files here:

http://www.maritime.org/sound/index.htm#soundinthesea

Interesting stuff.....those aren't the sounds used in this game though are they? :oops:

...No