maintaining depth at stop

PurpleCity · 01-25-09, 09:19 PM

My understanding is that submarines cannot maintain depth and will surface if engines are off. If I remember correctly, SHIII modeled this.

Is there a mod that simulates this behavior for SHIV or is this hardcoded in the game engine?

I'm also looking for 2 other mods with no luck
- is there a way to disable/hide/mask the hull damage indicator?
- is there a way to disable/hide those pesky icons in SHIV?

AVGWarhawk · 01-25-09, 09:22 PM

True, a submarine must maintain some forward motion to sustain depth. Some say the sub will rise and others say it will sink if there is no forward motion. That argument went on for sometime in SH3. At any rate, I believe this is hardcoded in SH4 and can not be addressed. There was some discussion at the RFB forums about this and I believe determined that this can not be modeled in SH4.

I do not have the answer for your last two.

tater · 01-25-09, 09:39 PM

Real subs didn't automatically broach if stopped. It was trim dependent, but trim varis from moment to moment, someone walks from one part to another of the sub, the water temp changes, etc, ad naseum. Unfortunately, the two solutions to hack this behavior into SH3 don't seem to work in SH4 (making the sub slowly surface all the time without down-planing, or having it slowly sinking without up-planing).

The simple solution for the gamer is to not stop the sub, or only rarely and for a very short time period, and never shoot while stopped. Easy enough to not cheat, really

Rockin Robbins · 01-25-09, 10:03 PM

There was an interesting exception to the rule that a sub had a lot of trouble maintaining depth at all stop. If the thermocline was enough different in temperature, there was a layer of dense cold water below a less dense layer of warm water. A submarine could set ballast to sink in the warm layer but still have enough positive buoyancy in the cold layer to sit there for a couple of days without power if they wanted to. A couple of times during the war that saved the subs' cookies, giving them the opportunity to shut everything down and affect repairs without worrying about depth-keeping or running out of battery power.

01-26-09, 08:17 AM

we all know subs pump water in or out to control depth

so think about it, if you were the skipper and you life depended on stealth, would you rather have negative boyancy so your sub sinks at all stop or positive boyancy so your ship will rise at all stop and get your head blown off.

positive or negative boyancy is not designed in, it is a setting chosen by the captain. plus if you want to dive faster like all subs do, then positive boyancy is going to be fighting you as you try to dive.

IMO all subs made sure they were at some level of negative boyancy any time they werent surfaced

Blood_splat · 01-26-09, 09:48 AM

What about firing torpedoes, would they have to adjust the trim to compensate before firing?

Soundman · 01-26-09, 11:31 AM

Quote:

Originally Posted by WEBSTER

we all know subs pump water in or out to control depth

so think about it, if you were the skipper and you life depended on stealth, would you rather have negative boyancy so your sub sinks at all stop or positive boyancy so your ship will rise at all stop and get your head blown off.

positive or negative boyancy is not designed in, it is a setting chosen by the captain. plus if you want to dive faster like all subs do, then positive boyancy is going to be fighting you as you try to dive.

IMO all subs made sure they were at some level of negative boyancy any time they werent surfaced

I completely see your point, but on the other hand, if something goes badly wrong, I wouldn't want to sink to crush depth either.

scott613 · 01-26-09, 12:33 PM

Don't know much about WWII subs - but - in modern subs - it was relatively easy to maintain depth without forward motion... The DOW and COW had to pay attention though... The newer subs even handle hovering automatically... Then there was always the infamous "TRIM PARTY" to indoctrinate a new officer into the wonderful world of depth control...

SteamWake · 01-26-09, 12:42 PM

A common misconception.... "Hover" does not indicat a full stop, more rather a few (1-3) knots, just enough to keep some flow over the planes to maintain depth and attitude yet not disrupt the launch of the unthinkable.

Rockin Robbins · 01-26-09, 02:19 PM

Scott, were you ever in a sub that floated on top of the layer? That sounds like it would be pretty amazing to do.

Rockin Robbins · 01-26-09, 03:04 PM

Quote:

Originally Posted by WEBSTER

IMO all subs made sure they were at some level of negative boyancy any time they werent surfaced

Webster, not to be offensive or anything, but we're not talking about opinion. We are talking about actual practice as verified by the people who actually ran the submarines.

In actual practice there was a tank called the negative buoyancy tank. Once per day the submarine took a "trim dive." Sub jockeys, check my accuracy here and keep me straight. In the trim dive, you dive the sub, slow it way down and with fore and aft trim tanks you level the boat. Somewhat simultaneously you fill or pump negative until the boat is at perfect negative buoyancy. The tank (in WWII anyway) is then marked at the level of neutral buoyancy. Fore and aft trim tanks are calibrated to know how bow or stern heavy the boat is. When a torpedo is fired, ballast equivalent to the weight of the torpedo being fired must be immediately added to the fore or aft trim tank to compensate for the lost weight and still leave the boat in balance.

Part of the diving procedure was to flood negative to the mark. Yes, you remember that, I see.

"The mark" would be that neutral buoyancy level established in the trim dive earlier in the day. That way, subject to any changes to conditions since the trim dive, the boat dove adjusted as closely as possible to neutral buoyancy.

Now I will speculate just like you :rotfl:, making an educated guess based on many books I have read by World War II submariners. If a submariner did something that departed from "the book," that would have been remarkable and noted in any of the books I have read. None of them have mentioned flooding negative to a level above the mark.

To me, that means that this part of the procedure was one that maybe was not required, but was one that captains were very reluctant to depart from, just like maintaining under a 10º dive angle, even though after the war the guppies successfully used dive angles that were much greater and speeded dive and surfacing times. Nonetheless, in spite of possible gains from changing the practice, during the war, captains were very precise about adhering to the official guidelines for diving and surfacing procedure.

tater · 01-26-09, 03:11 PM

RR, I don't know much about the guppies, but might it be fair to say the slower dive times in fleet boats were doctrinal, rather than hardware limited? Ie: they could go down faster had they put more than 10 degrees on the planes?

Rockin Robbins · 01-26-09, 03:32 PM

Yeah, you can say that again! Read Gallant Lady: A Biography of USS Archerfish for a FULL rundown on that. Matter of fact, that's EVERYBODY's reading assignment to read a book that's altogether too much fun to hold all that information. Their job was to find the real limits of the design and they did it to the point of hurting people because of the steep angles. They were among the first to really violate the guidelines, which were not orders, but were treated that way during the war.

Put yourself in the place of a sub captain. You choose to dive at 25º (which turned out from Archerfish's tests to be perfectly reasonable) but something unrelated went wrong and you lose some crewmembers. It's inquest time and they start asking questions. "Did you exceed the guideline of a 10º down bubble on the dive?" If you answer "Yes" the inquest is over and they have their scapegoat. Bend over. I see military people smiling and shaking their heads to that one.:rotfl:

tater · 01-26-09, 03:53 PM

How did that change the crash dive speed?

Bilge_Rat · 01-26-09, 04:49 PM

things can go wrong very quickly in a sub:

http://www.usschopper.com/Chopper%20...e%20Report.htm

part of the reason why sub skippers would not do a quick deep angle dive unless there was a compelling reason.

On the other point, ww2 subs were generally trimmed with a slight negative buoyancy and would use the planes and the forward motion to maintain depth. I don't remember all the reasons, but one is the fact that forward motion tends to impart positive buoyancy on its own due the water resistance/pressure which would cause the sub to rise. I think this is similar to the airlift principle with an airplane's wings. In practice, I understand it was also easier to maintain depth in this way rather than with a neutral or positive buoyancy.

01-25-09, 09:19 PM	#1
PurpleCity Loader Join Date: Jan 2009 Posts: 87 Downloads: 75 Uploads: 0	maintaining depth at stop My understanding is that submarines cannot maintain depth and will surface if engines are off. If I remember correctly, SHIII modeled this. Is there a mod that simulates this behavior for SHIV or is this hardcoded in the game engine? I'm also looking for 2 other mods with no luck - is there a way to disable/hide/mask the hull damage indicator? - is there a way to disable/hide those pesky icons in SHIV?

01-25-09, 09:22 PM	#2
AVGWarhawk Lucky Jack Join Date: Jun 2005 Location: In a 1954 Buick. Posts: 28,253 Downloads: 90 Uploads: 0	True, a submarine must maintain some forward motion to sustain depth. Some say the sub will rise and others say it will sink if there is no forward motion. That argument went on for sometime in SH3. At any rate, I believe this is hardcoded in SH4 and can not be addressed. There was some discussion at the RFB forums about this and I believe determined that this can not be modeled in SH4. I do not have the answer for your last two. __________________ “You're painfully alive in a drugged and dying culture.” ― Richard Yates, Revolutionary Road

01-25-09, 10:03 PM	#4
Rockin Robbins Navy Seal Join Date: Mar 2007 Location: DeLand, FL Posts: 8,900 Downloads: 135 Uploads: 52	There was an interesting exception to the rule that a sub had a lot of trouble maintaining depth at all stop. If the thermocline was enough different in temperature, there was a layer of dense cold water below a less dense layer of warm water. A submarine could set ballast to sink in the warm layer but still have enough positive buoyancy in the cold layer to sit there for a couple of days without power if they wanted to. A couple of times during the war that saved the subs' cookies, giving them the opportunity to shut everything down and affect repairs without worrying about depth-keeping or running out of battery power. __________________ Sub Skipper's Bag of Tricks, Slightly Subnuclear Mk 14 & Cutie, Slightly Subnuclear Deck Gun, EZPlot 2.0, TMOPlot, TMOKeys, SH4CMS

01-26-09, 12:33 PM	#8
scott613 Mate Join Date: Aug 2005 Posts: 60 Downloads: 37 Uploads: 0	Don't know much about WWII subs - but - in modern subs - it was relatively easy to maintain depth without forward motion... The DOW and COW had to pay attention though... The newer subs even handle hovering automatically... Then there was always the infamous "TRIM PARTY" to indoctrinate a new officer into the wonderful world of depth control... __________________ Thanks, Scott ET1/SS USS Flasher (SSN-613) 1985-1991 Last edited by scott613; 01-26-09 at 12:54 PM.

01-26-09, 02:19 PM	#10
Rockin Robbins Navy Seal Join Date: Mar 2007 Location: DeLand, FL Posts: 8,900 Downloads: 135 Uploads: 52	Scott, were you ever in a sub that floated on top of the layer? That sounds like it would be pretty amazing to do. __________________ Sub Skipper's Bag of Tricks, Slightly Subnuclear Mk 14 & Cutie, Slightly Subnuclear Deck Gun, EZPlot 2.0, TMOPlot, TMOKeys, SH4CMS

01-25-09, 09:39 PM	#3
tater Navy Seal Join Date: Mar 2007 Location: New Mexico, USA Posts: 9,023 Downloads: 8 Uploads: 2	Real subs didn't automatically broach if stopped. It was trim dependent, but trim varis from moment to moment, someone walks from one part to another of the sub, the water temp changes, etc, ad naseum. Unfortunately, the two solutions to hack this behavior into SH3 don't seem to work in SH4 (making the sub slowly surface all the time without down-planing, or having it slowly sinking without up-planing). The simple solution for the gamer is to not stop the sub, or only rarely and for a very short time period, and never shoot while stopped. Easy enough to not cheat, really

01-26-09, 08:17 AM	#5
Webster Stowaway Posts: n/a Downloads: Uploads:	we all know subs pump water in or out to control depth so think about it, if you were the skipper and you life depended on stealth, would you rather have negative boyancy so your sub sinks at all stop or positive boyancy so your ship will rise at all stop and get your head blown off. positive or negative boyancy is not designed in, it is a setting chosen by the captain. plus if you want to dive faster like all subs do, then positive boyancy is going to be fighting you as you try to dive. IMO all subs made sure they were at some level of negative boyancy any time they werent surfaced

01-26-09, 09:48 AM	#6
Blood_splat Samurai Navy Join Date: Aug 2006 Location: Beneath the waves Posts: 568 Downloads: 20 Uploads: 0	What about firing torpedoes, would they have to adjust the trim to compensate before firing?

01-26-09, 12:42 PM	#9
SteamWake Rear Admiral Join Date: Mar 2005 Posts: 13,224 Downloads: 5 Uploads: 0	A common misconception.... "Hover" does not indicat a full stop, more rather a few (1-3) knots, just enough to keep some flow over the planes to maintain depth and attitude yet not disrupt the launch of the unthinkable.

01-26-09, 03:11 PM	#12
tater Navy Seal Join Date: Mar 2007 Location: New Mexico, USA Posts: 9,023 Downloads: 8 Uploads: 2	RR, I don't know much about the guppies, but might it be fair to say the slower dive times in fleet boats were doctrinal, rather than hardware limited? Ie: they could go down faster had they put more than 10 degrees on the planes?

01-26-09, 03:32 PM	#13
Rockin Robbins Navy Seal Join Date: Mar 2007 Location: DeLand, FL Posts: 8,900 Downloads: 135 Uploads: 52	Yeah, you can say that again! Read Gallant Lady: A Biography of USS Archerfish for a FULL rundown on that. Matter of fact, that's EVERYBODY's reading assignment to read a book that's altogether too much fun to hold all that information. Their job was to find the real limits of the design and they did it to the point of hurting people because of the steep angles. They were among the first to really violate the guidelines, which were not orders, but were treated that way during the war. Put yourself in the place of a sub captain. You choose to dive at 25º (which turned out from Archerfish's tests to be perfectly reasonable) but something unrelated went wrong and you lose some crewmembers. It's inquest time and they start asking questions. "Did you exceed the guideline of a 10º down bubble on the dive?" If you answer "Yes" the inquest is over and they have their scapegoat. Bend over. I see military people smiling and shaking their heads to that one.:rotfl: __________________ Sub Skipper's Bag of Tricks, Slightly Subnuclear Mk 14 & Cutie, Slightly Subnuclear Deck Gun, EZPlot 2.0, TMOPlot, TMOKeys, SH4CMS

01-26-09, 03:53 PM	#14
tater Navy Seal Join Date: Mar 2007 Location: New Mexico, USA Posts: 9,023 Downloads: 8 Uploads: 2	How did that change the crash dive speed?

01-26-09, 04:49 PM	#15
Bilge_Rat Silent Hunter Join Date: Apr 2002 Location: standing watch... Posts: 3,855 Downloads: 344 Uploads: 0	things can go wrong very quickly in a sub: http://www.usschopper.com/Chopper%20...e%20Report.htm part of the reason why sub skippers would not do a quick deep angle dive unless there was a compelling reason. On the other point, ww2 subs were generally trimmed with a slight negative buoyancy and would use the planes and the forward motion to maintain depth. I don't remember all the reasons, but one is the fact that forward motion tends to impart positive buoyancy on its own due the water resistance/pressure which would cause the sub to rise. I think this is similar to the airlift principle with an airplane's wings. In practice, I understand it was also easier to maintain depth in this way rather than with a neutral or positive buoyancy.