Speed and quiet - 1/3 vs 2/3 vs full stop

[jerseytom]

I'm curious from an implementation standpoint - more a developer question - is noise level based more on reactor setting or knots?

So let's say we've got a Skipjack and a Sturgeon. Sturgeon is, by the game files, a quieter noise level boat. But is that at equivalent speed, or equivalent reactor setting?

For example, both boats going 20 knots. Skipjack may only have to be at Standard to achieve this, Sturgeon at Full (just guessing, without verifying in game). Will the Sturgeon be quieter at equivalent speed? Or is that nullified by the fact that it's running at a higher reactor setting?

[Capt Jack Harkness]

Not to nitpick but it's more of a throttle setting than a reactor setting.

[The Bandit]

Originally Posted by jerseytom

I'm curious from an implementation standpoint - more a developer question - is noise level based more on reactor setting or knots?

So let's say we've got a Skipjack and a Sturgeon. Sturgeon is, by the game files, a quieter noise level boat. But is that at equivalent speed, or equivalent reactor setting?

For example, both boats going 20 knots. Skipjack may only have to be at Standard to achieve this, Sturgeon at Full (just guessing, without verifying in game). Will the Sturgeon be quieter at equivalent speed? Or is that nullified by the fact that it's running at a higher reactor setting?

I don't believe relative plant noise is factored into the game. You have your ownship noise level as specified in the .txt file for the ship, which is then modified by whatever speed the ship is running at. So for something like a Skipjack or a November, that noise is going to be through the roof no matter what it is doing. Ditto for stuff like the Los Angeles or Narwhal being quiet.
The trouble is, this makes certain things (like the claims that the Alfa was actually a quiet boat until it was cranked up, or the "blade-rate" related noise suffered by the early Skipjacks and Permit class with 5 blade screws at certian speeds) impossible to replicate.

What I'm not sure about is whether or not Silent Running will bring you below the base noise-level or just down to it, but other than that you'd have ownship noise + speed modifier.

[Bubblehead Nuke]

This is something that is NEVER simulated correctly in any subsmin I have tried.

Basically the speed to noise curve is not a linear progression as it is always seemed to be modeled.

This is going to be a very general discussion for obvious reasons.

Here we go:

You have to look at what is going on.

The main noise you have on a boat is the propulsion plant in a nuclear powered vessel. It is the ONE thing that has to be on all the time. It is the single biggest creator of noise on the platform.

Now, with the plant running critical sitting at the pier, you may be using 25% of your reactor power to just keep the lights on and such. We call the 'hotel load' It is a constant amount of power that is required to operate the various equipment on the boat. This means that the remaining 75% of the available power is used to turn the screw.

A simplistic way to thing about speed is that each 'bell' is a doubling of power. Note that I did NOT say speed. Power is a cubed function in relation to speed. In essence, to double your speed you have to have 4 times the power to attain it.

Here are some basic numbers:

Ahead 1/3 is 5 knots
Ahead 2/3 is 10 knots
Ahead standard is 15 knots
Ahead full is 25 knots
Ahead flank is 30 knots

If you worked BACKWARDS, ahead flank is 100% reactor output. That is all out get the hell out of dodge thermal limit on the plant.

Ahead full is HALF of the amount of power, ahead standard is HALF of the power used for ahead full, and so on and so on.

So what is the difference between ahead 1/3 and ahead 2/3? Not very much if you do the math.

Now.. WHY is this important? Because you can increase your speed and have basically no increase in own ships noise up to a point.

What you DO have is a degradation in your sensors to DETECT the other guy. So while he may still not be able to hear you, you lose the ability to hear HIM and thus you have to get even closer to detect him.

The whole issue is about trading maneuverability and time for expediency. How much ocean can you cover and find the bad guy.

I wish they had some kind of simplistic model of reactor plant ops. Give you, the captain, some kind of tactical option. You can go into an area in low power mode. You are quieter, but you are speed limited. You can go in at high power ops and while you are noisy, you have better acceleration and higher speeds. Make it so that if you have to shift to power states you make HUGE 'here I am' transients. That way you have to think about what you are doing and how you are going to approach things.


Sorry for the ramble..

[jerseytom]

Ramble on! I was close-ish to going into a nuclear engineering program in college ~15 years ago, but opted the mechanical route instead. Interesting to hear the insight.

[FPSchazly]

Yes, please ramble on haha. I do nuclear engineering for transport packages but I'm always interested to hear the reactor side of things. Isn't the power required to overcome drag proportional to the cube of velocity?

[The Bandit]

Originally Posted by Bubblehead Nuke

This is something that is NEVER simulated correctly in any subsmin I have tried.

Basically the speed to noise curve is not a linear progression as it is always seemed to be modeled.

This is going to be a very general discussion for obvious reasons.

Here we go:

You have to look at what is going on.

The main noise you have on a boat is the propulsion plant in a nuclear powered vessel. It is the ONE thing that has to be on all the time. It is the single biggest creator of noise on the platform.

Now, with the plant running critical sitting at the pier, you may be using 25% of your reactor power to just keep the lights on and such. We call the 'hotel load' It is a constant amount of power that is required to operate the various equipment on the boat. This means that the remaining 75% of the available power is used to turn the screw.

A simplistic way to thing about speed is that each 'bell' is a doubling of power. Note that I did NOT say speed. Power is a cubed function in relation to speed. In essence, to double your speed you have to have 4 times the power to attain it.

Here are some basic numbers:

Ahead 1/3 is 5 knots
Ahead 2/3 is 10 knots
Ahead standard is 15 knots
Ahead full is 25 knots
Ahead flank is 30 knots

If you worked BACKWARDS, ahead flank is 100% reactor output. That is all out get the hell out of dodge thermal limit on the plant.

Ahead full is HALF of the amount of power, ahead standard is HALF of the power used for ahead full, and so on and so on.

So what is the difference between ahead 1/3 and ahead 2/3? Not very much if you do the math.

Now.. WHY is this important? Because you can increase your speed and have basically no increase in own ships noise up to a point.

What you DO have is a degradation in your sensors to DETECT the other guy. So while he may still not be able to hear you, you lose the ability to hear HIM and thus you have to get even closer to detect him.

The whole issue is about trading maneuverability and time for expediency. How much ocean can you cover and find the bad guy.

I wish they had some kind of simplistic model of reactor plant ops. Give you, the captain, some kind of tactical option. You can go into an area in low power mode. You are quieter, but you are speed limited. You can go in at high power ops and while you are noisy, you have better acceleration and higher speeds. Make it so that if you have to shift to power states you make HUGE 'here I am' transients. That way you have to think about what you are doing and how you are going to approach things.


Sorry for the ramble..

Originally Posted by jerseytom

Ramble on! I was close-ish to going into a nuclear engineering program in college ~15 years ago, but opted the mechanical route instead. Interesting to hear the insight.

2nd that, awesome explanation.
Also with the speed/noise curve. I think an outboard would be nice just for the circumstances / scenarios it could open up (thinking Cold is the Sea, Ned Beach's Cold War book about a crippled boomer stuck under the ice with just outboard propulsion) and it could probably be animated similarly to a periscope / any other retractable mast.

Rudimentary plant operation would be pretty cool, and who knows, if they ever decide to add diesel boats with their associated "control panel" for battery charging and whatnot it may be a possibility.

[Shadriss]

Originally Posted by Bubblehead Nuke

This is something that is NEVER simulated correctly in any subsmin I have tried.

Basically the speed to noise curve is not a linear progression as it is always seemed to be modeled.

This is going to be a very general discussion for obvious reasons.

Here we go:

You have to look at what is going on.

The main noise you have on a boat is the propulsion plant in a nuclear powered vessel. It is the ONE thing that has to be on all the time. It is the single biggest creator of noise on the platform.

Now, with the plant running critical sitting at the pier, you may be using 25% of your reactor power to just keep the lights on and such. We call the 'hotel load' It is a constant amount of power that is required to operate the various equipment on the boat. This means that the remaining 75% of the available power is used to turn the screw.

A simplistic way to thing about speed is that each 'bell' is a doubling of power. Note that I did NOT say speed. Power is a cubed function in relation to speed. In essence, to double your speed you have to have 4 times the power to attain it.

Here are some basic numbers:

Ahead 1/3 is 5 knots
Ahead 2/3 is 10 knots
Ahead standard is 15 knots
Ahead full is 25 knots
Ahead flank is 30 knots

If you worked BACKWARDS, ahead flank is 100% reactor output. That is all out get the hell out of dodge thermal limit on the plant.

Ahead full is HALF of the amount of power, ahead standard is HALF of the power used for ahead full, and so on and so on.

So what is the difference between ahead 1/3 and ahead 2/3? Not very much if you do the math.

Now.. WHY is this important? Because you can increase your speed and have basically no increase in own ships noise up to a point.

What you DO have is a degradation in your sensors to DETECT the other guy. So while he may still not be able to hear you, you lose the ability to hear HIM and thus you have to get even closer to detect him.

The whole issue is about trading maneuverability and time for expediency. How much ocean can you cover and find the bad guy.

I wish they had some kind of simplistic model of reactor plant ops. Give you, the captain, some kind of tactical option. You can go into an area in low power mode. You are quieter, but you are speed limited. You can go in at high power ops and while you are noisy, you have better acceleration and higher speeds. Make it so that if you have to shift to power states you make HUGE 'here I am' transients. That way you have to think about what you are doing and how you are going to approach things.


Sorry for the ramble..

There's the nuke side - the SONAR side of it adds even more complexity. Another thing that is rarely modeled well (if at all) is how O/S noise increases with speed. Not the equipment side that Nuke talked about, but simple flow noise across the hull.

Really, there's two numbers here to worry about. The first is ambient noise (which CW does use), basically the noise that's there as background. The second is O/S noise, which changes based on any number of large factors. These both matter greatly in speed selection. Why? Simple: I go slow enough that O/S noise doesn't significantly add to overall background, and I'm good. Any slower, and I gain nothing. I go fast enough that I can still hear. Any faster, and I gain nothing.

This happens in most subsims as pure chance - at least on the high side. The area that tends to be lost is the slow side - slow is not always quieter. There is a point where going any slower does not make you quieter... but it does cost you in terms of your control of the local tactical situation.

So, between the two... well, what I'll say is that I'd far rather cruise around at 10-ish knots than the 5 that CW's 'silent running' forces me into.

[Bubblehead Nuke]

Originally Posted by Shadriss

There's the nuke side - the SONAR side of it adds even more complexity.

I was actually expecting a sonar weenie to chime in. That is why I left that whole discussion out.

FYI. I was a nuke who actually QUALIFIED as a sonar operator. It made section tracking party MUCH easier as I knew what the heck they were actually talking about and could ask specific questions that were actually helpful.

I did not want to get into the sonar side as I am more comfortable beating around the bush on the engineering side and not giving away a capability or operational information by accident.

I am sure there are TONS of things you and I could nit pick and bellyache on. If they only implemented a tenth of the things we are generalizing about most peoples head would explode from the workload

[jerseytom]

Originally Posted by Bubblehead Nuke

If they only implemented a tenth of the things we are generalizing about most peoples head would explode from the workload

Probably the most important thing here. As with anything that exists for entertainment, you can take the fun factor out of it by making it too much like a job. Probably don't need to go as far as "Game Over: You have failed to qualify on virtual submarines."

Another consideration - a simple boat_noise = 132 in a configuration file is a lot more accessible from the standpoint of tuning things in a relative sense for gameplay, and also in keeping a mod community alive and well with future growth.

From an implementation standpoint I'd think it would be fairly trivial to have a table lookup for noise level versus speed. I would think though that there's got to only be a very limited number of people floating around here that could even subjectively describe what that curve should look like for any number of boats.

If it were me, and my experience from developing professional simulation software, my MO would be to ask - what all do we really need to capture as far as characteristics across a broad range (of diesel/electric and nuclear submarines in this case), and what's the absolute most simple way to implement it.

[Shadriss]

Originally Posted by Bubblehead Nuke

FYI. I was a nuke who actually QUALIFIED as a sonar operator.

A rare breed indeed. In 20 years of submarining, I can count the number of nuke-qualified SONAR operators I've worked with on no hands. Yes. That few. In which case, respect.... and mind your stack, Broadband.

Originally Posted by jerseytom

Probably the most important thing here. As with anything that exists for entertainment, you can take the fun factor out of it by making it too much like a job. Probably don't need to go as far as "Game Over: You have failed to qualify on virtual submarines."

Another consideration - a simple boat_noise = 132 in a configuration file is a lot more accessible from the standpoint of tuning things in a relative sense for gameplay, and also in keeping a mod community alive and well with future growth.

From an implementation standpoint I'd think it would be fairly trivial to have a table lookup for noise level versus speed. I would think though that there's got to only be a very limited number of people floating around here that could even subjectively describe what that curve should look like for any number of boats.

If it were me, and my experience from developing professional simulation software, my MO would be to ask - what all do we really need to capture as far as characteristics across a broad range (of diesel/electric and nuclear submarines in this case), and what's the absolute most simple way to implement it.

The way it's implemented here isn't bad, it's just very much overly pessimistic.

For Silent Running aka Ultra-Quiet, you have to understand that it's a machinery line up condition, and therefore, less the plant operations, speed independent. So yes - should definitely be unshackled from the 5 knot restriction. There will be a point where it's pointless to set ultra-quiet if you're going to go so fast (likely Standard Bell, for the purposes of this game), but even so there is no direct correlation between speed and ultra-quiet.

As for the speed-noise curve... it needs to be loosened up a bit. It's not as bad as I had originally thought, but after playing around a bit more, I can usually pull 10 knots and still be fine on most approaches.