A note about Water Pressure at depth. [Archive]

RedTerex

10-11-2004, 03:19 AM

Now this is a topic that effects us all, who like to play submarine sims...Water Pressure.

1 ATM ( atmosphere) or 1 Bar is 14.7 Lbs/per/square inch (psi) at sea level.

At 10 Meters or 33 feet the water pressure is 1 atm PLUS 1 atm (14.7Lbs/psi is ALWAYS THERE so it has to be added 'as well as' to any given sum of depth as an extra single unit)
viz, 14.7 Lbs/psi on the outside + the same on the inside pressing out at a fixed constant.

So we can now say:

10M or 33ft +1atm = 29.4Lbs/psi about 1 ton per square foot !

25M or 83ft +1atm = 51.7Lbs.psi about 2.5 tons per square foot !

50M or 166ft +1atm = 88.2Lbs/psi about 5 tons per square foot !

100M or 333ft +1atm = 161.7Lbs/psi about 10 tons per square foot !

200M or 666ft +1atm = 455.7lbs/psi about 20 tons per square foot ! which would be 100s of thousands of tons of water pressure squeezing the entire sub at this depth a.k.a C-R-U-S-H-E-D like an egg shell!!

These are my own calculations based on the atm formula.

Analogy rules:
Water is quite heavy, just fill up a single bucket of water and hold it out at arms length.
Now imagine about 33 buckets all full of water standing on the top of each other...thats a lot of real weight pressing down on the same spot. That would be the equivalent of just 10 metres deep for the surface area of the bucket !

When our subs go down to say 150 feet thats a lot of buckets pressing down in the same spot, times the entire surface area.

Water pressure is a real issue where subs are concerned and you dont have to dive relatively that deep to encounter these pressures.

Just food for thought there guys !

SailorSteve

10-11-2004, 09:50 AM

Good points. Now when I play AOD/SHII/SHIII I'll be constantly staring at the walls and saying "It's only a game! It's only a game!".

bertgang

10-11-2004, 10:44 AM

Lot of holes in my walls, for pictures and so on!
The hull integrity of my flat is in danger.

Jose.MaC

10-11-2004, 03:15 PM

I'm not sure of how WWII subs managed air while submerged. If they just relied in their volume of air, a VII had just PI*(4,7/2)^2 * 50,5 = 876,15 m3 of air. If a man needs the oxigen contained in 6 m3 per hour (don't take me too seriously, I don't know the exact figures), then a crew of 45 men will be able to breath for no more than 3h 14' 42".

If they use compressed air to keep the atmosfera of the sub breathable, it means they'll increase the pressure as time passes, so the longer they're submerged, the less precision they'll have about depth (they'll think they're shallower whenever fresh air is injected in the sub).

Will be this modelled in the game? This was the reason they were unable to keep torpedoes in the right depth.

macker33

10-11-2004, 10:17 PM

I know this much,1 liter of water weights exactly 1 kilogramme which is 2.2lbs.

Jose.MaC

10-12-2004, 02:16 AM

and is equal to a cubic centimeter! Those mad frenchmen! http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif

radsov

10-12-2004, 03:43 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by Jose.MaC:
If a man needs the oxigen contained in 6 m3 per hour (don't take me too seriously, I don't know the exact figures), then a crew of 45 men will be able to breath for no more than 3h 14' 42".
<HR></BLOCKQUOTE>

It isn't the lack of oxygen that would kill you first but the increase in carbon dioxide. This doesn't have to rise very much before it becomes toxic. If you can remove the extra carbon dioxide then you can re-breathe old air and extract more oxygen from it several times. This is the principle of a re-breather used in diving. I believe (but I'm not sure by any means so if someone knows better) that the subs of all navy's had some sort of carbon dioxide scrubbers that removed extra carbon dioxide to keep it at safe levels. Doing this allowed them to remain submerged on the bottom safely for many many hours at a time. In operation Drumbeat some would stay on the bottom during all day light hours and come up at night.

jeroen-79

10-12-2004, 04:58 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by Jose.MaC:
and is equal to a cubic centimeter! Those mad frenchmen! http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif <HR></BLOCKQUOTE>No, 1 liter = 1 cubic decimeter = 1000 cubic centimeter.

Also, 1 kg/l applies to pure water.
Water with stuff dissolved in it is denser.

TASKFORCE1x1

10-12-2004, 07:04 AM

JUst think about the pin hole leaks at that depth also now. With all that pressure I think its true to say that a high pressure stream of water spraying in the sub can cut people. Kinda like the 1300lb pressure washer I have. That was able to cut a piece of old sheet rock I had laying near my trash cans. Think what it could do to skin and bone. http://forums.ubi.com/images/smilies/16x16_smiley-surprised.gif

Jose.MaC

10-12-2004, 09:12 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by jeroen-79:
<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by Jose.MaC:
and is equal to a cubic centimeter! Those mad frenchmen! http://forums.ubi.com/groupee_common/emoticons/icon_biggrin.gif <HR></BLOCKQUOTE>No, 1 liter = 1 cubic decimeter = 1000 cubic centimeter.

Also, 1 kg/l applies to pure water.
Water with stuff dissolved in it is denser. <HR></BLOCKQUOTE>

True! This memory of me! http://forums.ubi.com/groupee_common/emoticons/icon_redface.gif

Jose.MaC

10-12-2004, 09:17 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by radsov:
<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by Jose.MaC:
If a man needs the oxigen contained in 6 m3 per hour (don't take me too seriously, I don't know the exact figures), then a crew of 45 men will be able to breath for no more than 3h 14' 42".
<HR></BLOCKQUOTE>

It isn't the lack of oxygen that would kill you first but the increase in carbon dioxide. This doesn't have to rise very much before it becomes toxic. If you can remove the extra carbon dioxide then you can re-breathe old air and extract more oxygen from it several times. This is the principle of a re-breather used in diving. I believe (but I'm not sure by any means so if someone knows better) that the subs of all navy's had some sort of carbon dioxide scrubbers that removed extra carbon dioxide to keep it at safe levels. Doing this allowed them to remain submerged on the bottom safely for many many hours at a time. In operation Drumbeat some would stay on the bottom during all day light hours and come up at night. <HR></BLOCKQUOTE>

Yup, there are lots of chemical systems to do that. Jules Verne sets one in "From the Earth to the Moon" and "Arround the Moon". So there was one in both Ictineo I and II (was claimed to set air with a "fresh" aroma, good for the crew morale). But since in "Das Boot" the crew appears using individual cilinders I was dubious about this particular point. BTW, I thought carbon monoxide was the poisonous one.

radsov

10-12-2004, 09:44 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by Jose.MaC: BTW, I thought carbon monoxide was the poisonous one. <HR></BLOCKQUOTE>

Carbon Monoxide is very poisonous as you say. But it's not normally present in air and we do not exhale it as a by product of breathing. What we do do is intake oxygen and exhale carbon dioxide. However if the level of this gas rises (not that much but don't have figures to hand) in our bloodstream due to inhalation it becomes toxic to our systems (not just a suffication effect). When Appollo 13 had it's accident one of the first things the ground team had to work out was how to build make-shift carbon dioxide scrubber from what they had on board. They had enough oxygen technically but without a means to remove the breathed out carbon dioxide they would have died before the oxygen ran out.

radsov

10-12-2004, 09:53 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>BTW, I thought carbon monoxide was the poisonous one. <HR></BLOCKQUOTE>

I've had a quick search on the nasa web site and here's a quick quote

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>After a day and a half in the LM a warning light showed that the carbon dioxide had built up to a dangerous level. Mission Control devised a way to attach the CM canisters to the LM system by using plastic bags, cardboard, and tape- all materials carried on board. <HR></BLOCKQUOTE>

Here's the link where I got this quote from
http://science.ksc.nasa.gov/history/apollo/apollo-13/apollo-13.html

Jose.MaC

10-12-2004, 03:25 PM

Wouldn't like being neither in the capsule nor in the command center!

Great info! Thks!

Frank_Torpex

10-12-2004, 04:42 PM

Ok, just to "set the record straight"....

1-The air pressure inside the submarine is never adjusted to "compensate" for the increased water pressure. Any air that did build up in the sub (modern or WWII) does so as a result of aire leaks, torpedo tube ops, or trim adjustments. In fact some S-Class subs has pneumatically controlled eletrical switches which slowly drained the air banks, and caused the pressure to rise in the sub. If subs did raise the pressure, prior to surfacing they would require to be decompressed, a lengthy and very necessary procedure to prevent the bends and after enough times, death.

Now about water pressure, Bottom line is this: For every 100 ft the sea pressure is 44 psi. So at 200 = 88 psi, 1000 ft the sea pressure is 440 psi, etc.

All that from your friendly neighborhood fast attack submariner. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Frank
Subsim Staff

Jose.MaC

10-12-2004, 06:43 PM

To have all your crew killed for such problem would be interesting http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif "The sub managed to surface, but we just found dead bodies inside. No evidences of violence, Sir."

Mamersk

10-13-2004, 06:44 AM

From working on modern submarines I can tell you that onboard they have O2 Cannisters. They also have CO2 scrubbers and they also have oxygen candles... These are special candles that when they burn they actually release O2... (I hope I havent released any classified stuff!!)

1lt of FRESH water weights 1kg
1lt of SEA water will weight more than 1kg because of all the other stuff in it like salt. Submarine crews actually used to have to measure the salinity of the sea water daily to work out the boats boyancy values and the amount of compressed air required to re-surface after a dive. Different areas have more or less salt... hence more or less density and boyancy... (I think)...

jeroen-79

10-13-2004, 09:02 AM

SailorSteve

10-13-2004, 09:56 AM

Well, carbod dioxide technically isn't a poison...you just can't survive on it! http://forums.ubi.com/images/smilies/88.gif

Jose.MaC

10-13-2004, 01:02 PM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by Mamersk:
From working on modern submarines I can tell you that onboard they have O2 Cannisters. They also have CO2 scrubbers and they also have oxygen candles... These are special candles that when they burn they actually release O2... (I hope I havent released any classified stuff!!)

1lt of FRESH water weights 1kg
1lt of SEA water will weight more than 1kg because of all the other stuff in it like salt. Submarine crews actually used to have to measure the salinity of the sea water daily to work out the boats boyancy values and the amount of compressed air required to re-surface after a dive. Different areas have more or less salt... hence more or less density and boyancy... (I think)... <HR></BLOCKQUOTE>

Amazing! So those candles must get the carbon and free the oxigen from carbon dioxid! Should study the chemical reaction, but looks feasible.

You're right about the specific weight of sea water. In fact, if ever you began to manage an aquarius, you'll discover yourself testing it with a device that relies in its boyancy. Pretty acurate.

radsov

10-14-2004, 03:58 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by SailorSteve:
Well, carbod dioxide technically isn't a poison...you just can't survive on it! http://forums.ubi.com/images/smilies/88.gif <HR></BLOCKQUOTE>

Carbon dioxide is one of those such common things that it is presumed not to be poisonous, quite a few web sites and sources compare it to carbon monoxide, saying one is poisonous and the other not. When in fact C-monoxide is extremely poisionus and C-dioxide is considered harmless at low levels but it is still actually a posion. At more than 15% concentration in air it becomes a narcotic poison. Here are two links explaining this, the first details the effect on humans and the second how the removal of it is important in submarines (this seems to be aimed at a younger audience but it seems to explain things nicely.)

http://www.therhondda.co.uk/gases/carbon_dioxide.html
http://express.howstuffworks.com/express-submarine2.htm

You could liken Carbon dioxide to alchohol, which in small doses is deemed to be benificial to the body and the body copes with this fine. In large doses however it becomes harmful and in some cases you can have alcoholic poisioning (which can be fatel). http://forums.ubi.com/groupee_common/emoticons/icon_frown.gif

Philipscdrw

10-14-2004, 05:07 AM

Also, alcohol is dangerous in large concentrations because it lowers your inhibitions and may cause you to say things to your attactive female flatmate which you would regret saying in the morning if you could actually remember it.

SailorSteve

10-14-2004, 10:08 AM

Radsov, I found a couple more sites which agree with you, and this one (at first pass) which doesn't:
http://www.ilpi.com/msds/ref/carbondioxide.html

bertgang

10-14-2004, 10:34 AM

It sounds a bit strange to call "poison" the carbon dioxid.

We drink it with soda water, coca cola and lot of other drinks.

Jose.MaC

10-14-2004, 02:19 PM

Hey! You dind't read the whole page! The point is that we cannot take O2 from air if there is too much CO2, about a 10%. The page even gives the chemical reactions!

And in this link http://www.osha-slc.gov/dts/hib/hib_data/hib19960605.html in the same page, you have this info:

"Carbon dioxide is a colorless, odorless gas and should be treated as a material with poor warning properties. It is denser than air and high concentrations can persist in open pits and other areas below grade. The current OSHA standard is 5000 ppm as an 8-hour time-weighted average (TWA) concentration.

Gaseous carbon dioxide is an asphyxiant. Concentrations of 10% (100,000 ppm) or more can produce unconsciousness or death. Lower concentrations may cause headache, sweating, rapid breathing, increased heartbeat, shortness of breath, dizziness, mental depression, visual disturbances or shaking. The seriousness of the latter symptoms is dependent on the concentration of carbon dioxide and the length of time the individual is exposed. The response to carbon dioxide inhalation varies greatly even in healthy normal individuals."

If you use a CO2 estinguisher, you have about 2 or 2.5 kg of CO2 (only about 9 seconds of action! Never be too entushiastic when using a fire estinguisher!), wich is an small amount, and get soluted into the air in no time.

So there is no further point to argue. Before reaching a 10% of CO2, a sub must surface!

mlody111

10-14-2004, 06:45 PM

When I saw this post I just couldnt resist in adding my thoughts.

About Gases:
I am a fanatic when it comes to aquariums and plants which has taught me alot about the dissolution of gases as well as their concentrations.
Carbon Monoxide - This gase is extremely poisonus because it binds to our hemoglobin permanently and from this point on it is useless. So now our body has to create more hemoglobin which takes time.
Carbon Dioxide - This gases displaces oxygen when it comes in contact with hemoglobin. Which means that either O2 or CO2 binds to hemoglobin, which ever is at a higher concentration in the air (even if O2 is higher, it may not be high enough).

The Super-saturated oxygen candles were not available in ww2. The only device they had was the CO2 scrubbers with did increase the breathing time.

Water pressures:
1 liter of water = 1 kg
if we take an area of 1 square meter on the submarine we now can multiply by the number of meters above the hull. so 1m^2 * depth = m^3 * conversion. Conversion = 1m^3 = 1000 liters = 1000kg so 200meters * 1 m^2 = 200 * 1000 = 200,000 kg!

so this means the pressure is 200,000kg per square meter. 1Kg = 2.20462262 pounds and 1 meter = 3.2808399 feet so (200,000 Kg/m^3) / (3.281 ft)^2 * (2.205 lb) = 40,996 lb per = 41,000lbs per square foot or (284.5 lbs per square inch!) This means that you have to support yourself plus 1/2 on your thumb!

It is not twice this just beause of newton's third law. Pressure is exactly this... but the tension inside the metal (treat the metal as a cable) is 569 lbs per square inch! This is how much pressure the metal block feels (the actual plate of metal that is between the side of the sub and the outside).

macker33

10-14-2004, 07:50 PM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by Bertgang:
It sounds a bit strange to call "poison" the carbon dioxid.

We drink it with soda water, coca cola and lot of other drinks. <HR></BLOCKQUOTE>

People are too health conscious nowadays,there are people who call ***s poisen.When fate says your numbers up your numbers up and thats all there is.

radsov

10-15-2004, 01:37 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by SailorSteve:
Radsov, I found a couple more sites which agree with you, and this one (at first pass) which doesn't:
http://www.ilpi.com/msds/ref/carbondioxide.html <HR></BLOCKQUOTE>

SailorSteve, Yes I've come across more pages that don't mention it's toxicity than do. Which I think is down basically to the fact that in normal concentrations it just can't harm your body, even drinking it in with carbonated drinks. Jose.Mac and mlody111 have explained things better than I so I won't go over any old ground there.

Thanks for the link. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

Actually, changing tack a little, is your avatar image actually a picture of you fishing off some ship (looks like a ship), if so what type was it ?

SailorSteve

10-15-2004, 05:53 PM

Actually it's me posing with a .50 caliber (12.7mm) machine gun on my destroyer, USS Brinkley Bass (DD-887), in Manila Harbor back in 1970. Here's a close up http://mywebpage.netscape.com/sebradfield/images/sailor%20steve.jpg
and here's a different one
http://mywebpage.netscape.com/sebradfield/images/steve%203.jpg
I posted these on another thread a while back, but since you asked, I couldn't resist.

radsov

10-16-2004, 01:42 AM

Thanks for the pictures. Sorry about mistaking it for a fishing rod, looks like that as a thumbnail !

radsov

10-17-2004, 07:03 AM

For those that have been following the parts of this thread about carbon dioxide.

I mentioned in an earlier post that I did not know what u-boats used to remove carbon dioxide and presumed they had some sort of carbon dioxide scrubber and if anyone knew any better to post it here. Well as I've mentioned in another post I've just had the wonderful opportunity to tour U534 (Link to that post -> http://forums.ubi.com/eve/forums?a=tpc&s=400102&f=857101043&m=5421021132). And one of the questions I asked the very knowledgeable submariner who showed us round the sub was what they used to remove carbon dioxide.

He took us to the electric motor compartment (I'm sure it was this one) and showed use rectangular metal boxes lining the corridor on either side (around 10 per side) and of around 10 litre capacity each (not sure what that is in gallons for imperial/US people). These we were informed were full with Soda Lime, a substances that absorbs carbon dioxide. They would simply scoop some out of the bins and sprinkle it around the floors (presumably throughout the sub). I don't believe there was anyway to monitor how much CO2 was in the air but I'd guess they were told to use so many scoops every hour or whatever whilst running on batteries, I bet this is in the operations manual for the boat.

So, there you have it, Soda Lime sprinkled on the floor !

RedTerex

10-17-2004, 09:00 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by SailorSteve:
Actually it's me posing with a .50 caliber (12.7mm) machine gun on my destroyer, USS Brinkley Bass (DD-887), in Manila Harbor back in 1970. Here's a close up http://mywebpage.netscape.com/sebradfield/images/sailor%20steve.jpg
and here's a different one
http://mywebpage.netscape.com/sebradfield/images/steve%203.jpg
I posted these on another thread a while back, but since you asked, I couldn't resist. <HR></BLOCKQUOTE>

Yeah thats a cool photo SailorSteve, that 50cal sure looks like a big machine gun, either that or your one small guy http://forums.ubi.com/images/smilies/16x16_smiley-wink.gif http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

I have to admit that I liked the 70's, best decade ever. I was at school at the time though.

You were (as stated)in the USN at that time, what was your role on the ship?
And please dont say " fisherman" LOL

SailorSteve

10-17-2004, 10:29 AM

I would describe myself as sort of 'average': 5'8", 145 pounds (then, 190 now), so yeah, it's a fair sized toy.

I was a radioman. We had two of the .50s; we radiomen trained with one, the signalmen had the other. It was fun.

RedTerex

10-17-2004, 01:49 PM

I remember being shown an inert .50 Cal round some years ago and I was amazed at the size of those things.The bread and butter guns of the USA.
The Thunderbolt P-47 WWII plane ( my favourite WWII plane incidently) had a masssive array of 8 .50 cal machine guns, 4 in each wing. And that was a lot of firepower LOL. The P-51 Mustang only>>>I say only with trepidation<<<had 6 .50 cals.

Whats all this to do with U-boat forums I here you all cry?

Well...IF we get straifed by a P-47 whilst out in the Meditteranean those .50's would damage our relativley fragile sub...no problem !

hauitsme

10-17-2004, 02:37 PM

I have no 'favorite' since there are so many to choose from and they each have their own strengths and weaknesses. But one of them to keep an eye out for would definitely be the B-25, particularly the 'J' version. You think 8 .50's of the P-47 were bad, how about 12 forward firing .50's, let alone the bombload capability!! Some even had FF cannon installed too. One of the first 'Gunships' built just for ground attack.
http://www.hill.af.mil/museum/photos/wwii/b25j.jpg

Frank_Torpex

10-17-2004, 04:23 PM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR> Water pressures:
1 liter of water = 1 kg
if we take an area of 1 square meter on the submarine we now can multiply by the number of meters above the hull. so 1m^2 * depth = m^3 * conversion. Conversion = 1m^3 = 1000 liters = 1000kg so 200meters * 1 m^2 = 200 * 1000 = 200,000 kg!

so this means the pressure is 200,000kg per square meter. 1Kg = 2.20462262 pounds and 1 meter = 3.2808399 feet so (200,000 Kg/m^3) / (3.281 ft)^2 * (2.205 lb) = 40,996 lb per = 41,000lbs per square foot or (284.5 lbs per square inch!) This means that you have to support yourself plus 1/2 on your thumb!

It is not twice this just beause of newton's third law. Pressure is exactly this... but the tension inside the metal (treat the metal as a cable) is 569 lbs per square inch! This is how much pressure the metal block feels (the actual plate of metal that is between the side of the sub and the outside). <HR></BLOCKQUOTE>

So, what exactly does all that say? LOL Does all that convert over to 44psi per 100 ft?

Frank

RedTerex

10-17-2004, 06:42 PM

Hauitsme Quote: "...how about 12 forward firing .50's..."

Yes please! that will do nicely. A one second burst would deliver about 1200 rounds onto the unfortunate target @ 12 x 650RPM / 60
Nice pic of the B-25 too.

SailorSteve

10-17-2004, 08:22 PM

Umm...I just did that math and only came up with 130 rounds from a one second burst, not 1200.

hauitsme

10-17-2004, 08:34 PM

He forgot to mention that they were 'fragmentation' rounds that break up into 9.23 pieces each!!

Still, to have something shooting 7,800 RPM at you isn't something to shake your fist at!http://img.photobucket.com/albums/v325/hauitsme/sweaty.gif

macker33

10-17-2004, 09:38 PM

How much space does one liter of water occupy again?

mlody111

10-17-2004, 10:45 PM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR> So, what exactly does all that say? LOL Does all that convert over to 44psi per 100 ft? <HR></BLOCKQUOTE>

PSI = pounds per square inch

I wrote...
<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR> 41,000lbs per square foot or (284.5 lbs per square inch!) This means that you have to support yourself plus 1/2 on your thumb!
<HR></BLOCKQUOTE>

lbs = pounds.... 284.5 pounds per square inch = psi

So if you wanted to empty your ballast tanks, you would need a minimum pressure of 284.6 psi of air to blow the water out. This can be take one step father...

With a bit of math you can actually calculate the time it takes to dump out the water from your balast tanks at a given depth
(yes, the time to dump the water from you tanks changes as you go deeper... either that or the amount of air you use... either way it all relates to pressure and depth)

if we are at 200 meters with 600 psi of air pressure in our tanks we want to empty 1000 liters of water through a 1 meter by 1 meter hole and the holding tank is 1 meter deep, it would take you about .000467 seconds

at 300 psi t = .1204 seconds
I wonder if this is included into the code for SHIII http://forums.ubi.com/images/smilies/1072.gif what a waste of time...
I dont think I would even want my processor to waste time calculating .12 of a second in delay for a change in bouyancy. http://forums.ubi.com/images/smilies/34.gif

Now dive planes and inertia of the sub, now thats someting to worry about in a delay for surfacing. http://forums.ubi.com/images/smilies/35.gif

mlody111

10-17-2004, 10:48 PM

Sorr for the double post, but 1 meter X 1 meter X 1 meter of space holds 1,000 Liters of water

1 m^3 = 1,000 L

U-553

10-18-2004, 12:40 AM

The water Pressure is the same all around the uboat, the pressure is not just on top of the sub. All uboat had a pressurehull formed like an eegshell, so it wouldn't cruss that easy.
lots of openings made the hull very veke.

munnst

10-18-2004, 05:45 AM

What I want to know is will the sprung hull plates react to depth and explosion as in real life.
From what I understand real uboats skins were sprung to absorb the pressure of explosions. That's why there are sudden leaks and water jets after a near miss.
Also will there be creaking and groaning sounds as well as the popping of rivets when going too deep.

mlody111

10-18-2004, 09:55 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR> The water Pressure is the same all around the uboat, the pressure is not just on top of the sub. All uboat had a pressurehull formed like an eegshell, so it wouldn't cruss that easy.
<HR></BLOCKQUOTE>

Its true that the pressure is not only on the top, but it is not true that the pressure is the same all around. The pressure varies in depth and the bottom of the boat is under higher pressure then the top of the boat

If you would use an eggshell for the construction imagine this... an eggshell is very strong when pressing on the long ends, try pushing on the sides of the eggshell, splat! If there is pressure all around, that means it is on the side as well making the eggshell snap like a toothpick.

QUOTE] From what I understand real uboats skins were sprung to absorb the pressure of explosions. That's why there are sudden leaks and water jets after a near miss. [/QUOTE]

I understand how that works... could you explain a bit more about this?

Frank_Torpex

10-18-2004, 05:54 PM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR> 41,000lbs per square foot or (284.5 lbs per square inch!) This means that you have to support yourself plus 1/2 on your thumb!

--------------------------------------------------------------------------------

lbs = pounds.... 284.5 pounds per square inch = psi

So if you wanted to empty your ballast tanks, you would need a minimum pressure of 284.6 psi of air to blow the water out. This can be take one step father...
<HR></BLOCKQUOTE>

LOL Now dont get irritated, but at WHAT depth does your formula (284.5 pounds per square inch ) relate to? http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif I am guessing about 640ft?

Frank

mlody111

10-18-2004, 08:49 PM

at 200 meters. which is 656.2 ft. so yea about 640 ft

macker33

10-19-2004, 12:49 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by mlody111:
Sorr for the double post, but 1 meter X 1 meter X 1 meter of space holds 1,000 Liters of water

1 m^3 = 1,000 L <HR></BLOCKQUOTE>

Thats appreciated.

Philipscdrw

10-19-2004, 09:37 AM

one litre: 10cm x 10cm x 10cm
one litre = 1000 cubic centimetres.

I remember reading that James Martin (of Martin-Baker ejector seat company) managed to pack about 12MGs into the nose of the DB-7, for interception of bombers.

rlbroke

10-19-2004, 01:27 PM

3 litres of water = 6000 cubic centimeters which is approximately 6 large glasses. If you add a few psi of Carbon Dioxide, approximately .5 litres of alcohol and several frozen units of H20, you get enough Gin and Tonic that you don't give a durn about the fact that your sub is being crushed by all that water. http://forums.ubi.com/images/smilies/53.gif

Frank_Torpex

10-19-2004, 03:28 PM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>at 200 meters. which is 656.2 ft. so yea about 640 ft <HR></BLOCKQUOTE>
Ok..so it is the same formula. I like mine beter only because its quicker. http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Frank

mlody111

10-19-2004, 08:03 PM

yours maybe be easier, but mine is more versitle http://forums.ubi.com/images/smilies/mockface.gif

Boatfull

10-20-2004, 07:53 PM

In the movie Das boot,when one of the men freaks out
and heads for the hatch he is held back by the others

because of water pressure there is no way he can open
the hatch right?

you would think a sub guy would now this but he is
freaking out. http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

mlody111

10-21-2004, 03:45 PM

Thats true, but there is a way to get out of the sub while underwater... that is if your not crushed at that depth yourself.

Once the sub is full of water, opening the hatch shouldnt be too hard and if you have enough air, swim to the surface. My question is... how much pressure can the human body survive without pressure suits?

SailorSteve

10-21-2004, 03:54 PM

People have dived pretty deep, but I see two problems with that scenario:

1) Even at a shallow depth it's not the actual water pressure, but the sudden inrush of water at very high pressure that knocks your breath out so you can't possibly hold it; and also crushes you real good.

2) Even if the boat fills up slowly, and you manage to hold your breath while you open the hatch, that doesn't do much for the 20 or so guys waiting behind you; and that's assuming you are so well trained you don't panic and kill each other trying to be the first one to the hatch.

That said, I know that the U.S. Navy did have extensive evacuation training, so the concept was there.

radsov

10-22-2004, 02:27 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by SailorSteve:

2) Even if the boat fills up slowly, and you manage to hold your breath while you open the hatch, that doesn't do much for the 20 or so guys waiting behind you; and that's assuming you are so well trained you don't panic and kill each other trying to be the first one to the hatch.

That said, I know that the U.S. Navy did have extensive evacuation training, so the concept was there. <HR></BLOCKQUOTE>

You don't need to hold your breath, all subs of all Navy's back in WW1 and WW2 (as far as I'm aware) had rebreathers on board, they looked like life jackets but had a breathing mask, in, built carbon dioxide scrubbers and air canister. These would allow you to breath for enough time for the compartment to flood and escape to the surface with air to spare. Here is a picture of a rebreather used on U-boats.

http://uk.geocities.com/uboat_534/rebreather.gif

As to what depth you could escape a sub from... I'm not sure what the record is.

U534's crew trapped in the forward torpedo room escaped with re-breathers from around 100ft, although the last crew member to evacuate got his rebreather caught on the way out and calmly cut it free, disgarded it and free assented to the top. He was the oldest crew member in that compartment and took command ensuring all the younger submariners escaped first before himself, he was just 17. I think they're training and intgrity were excellent.

SailorSteve

10-22-2004, 12:23 PM

I didn't know that part-cool!

Frank_Torpex

10-22-2004, 04:11 PM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by mlody111:
yours maybe be easier, but mine is more versitle http://forums.ubi.com/images/smilies/mockface.gif <HR></BLOCKQUOTE> That may be true! http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

Now..WHY is all this pressure stuff important..(I know I am just wondering if anyone else knows-ESPECIALLY the Dev team). http://forums.ubi.com/images/smilies/heart.gif
I'll take three tries (I doubt any will be "wrong", I am just wondering if anyone else could see how this will affect game play)

Frank

mlody111

10-22-2004, 08:39 PM

Try 1: Pressures are diffrent in diffrent areas of the oceans/lakes. The more salt/Mineral content in the water the more pressure there is because the water is heavier. If the games was modelled with the boat's allowable pressure instead of max depth, this way we can mimic nature.

Try 2: Strong currents also create more pressure and again if the max depth was modelled with pressure instead of meters, it is easier to expand the game to mimic nature. This way it is possible to have a max depth of 120 meters instead of 150 meter becaues of the bigger pressure

Try 3: The rate of flooding I beleive also depends on the depth of the boat... this can be modelled by meters, but again mimics nature better with pressure.

Try 4: The efficency of depth charges changes as the depth of the boat changes.

Try 5: The rate of ascent or the amount of air you use changes with pressure (slightly, but still does). Again this can be modelled using meters as the variable, but using pressure adds alot more room to expanding the game to mimic nature better.

Im sure there are some other reasons... Lets see who and what else we can think of.

hauitsme

10-22-2004, 08:59 PM

Don't pressure me...
I'll think of something.

Frank_Torpex

10-23-2004, 06:36 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by mlody111:
Try 1: Pressures are diffrent in diffrent areas of the oceans/lakes. The more salt/Mineral content in the water the more pressure there is because the water is heavier. If the games was modelled with the boat's allowable pressure instead of max depth, this way we can mimic nature.

Try 2: Strong currents also create more pressure and again if the max depth was modelled with pressure instead of meters, it is easier to expand the game to mimic nature. This way it is possible to have a max depth of 120 meters instead of 150 meter becaues of the bigger pressure

Try 3: The rate of flooding I beleive also depends on the depth of the boat... this can be modelled by meters, but again mimics nature better with pressure.

Try 4: The efficency of depth charges changes as the depth of the boat changes.

Try 5: The rate of ascent or the amount of air you use changes with pressure (slightly, but still does). Again this can be modelled using meters as the variable, but using pressure adds alot more room to expanding the game to mimic nature better.

Im sure there are some other reasons... Lets see who and what else we can think of. <HR></BLOCKQUOTE>

Not so sure I agree with 1 & 2, but 3-4-5 are all definitly game play issues. Number 3 being the one I was looking for.

The reason that the Officer who is controlling the ballasting/depth control (on US Subs this Officer was/is known as the "Diving Officer") needs accurate damage reports is because he will then know the estimated pounds per minute the sub is flooding. Why?

Every submarine that submerges has a certain amount of "reserve" bouyancy calculated into its construction. Thats why when a submarine submerges it doesnt actually get heavier, it simply changes displacement. Therfore, the difference between surfaced displacemet and surfaced displacement is a % of reserve bouyancy. Why the diving Officer needs to know where the flooding is coming from is to enable him to calculate the amount of water coming in-how fast the reserve bouyancy is being used up-or if he must immediately blow main ballast (creating a % of surfaced dispacemet while submerged) So if a flange in a 1" sea water system bursts at 700 feet-believe it or not he only has about a minute to stop the flooding before he must order the ballast blown! Where at 100 feet-that is not that big a problem. At 700 feet..imagine trying to put a plug in that hole with 440 psi behind it! Now imagine putting your hand over a garden hose end with the water pressure at 40-50 psi! http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif

So IMHO, the Dev team, if they modeled the damage model correctly (Give or take) then knowing where the flooding is coming at various depths from makes a huge difference in how we use our subs.

Frank

Jose.MaC

10-23-2004, 07:51 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by radsov:
You don't need to hold your breath, all subs of all Navy's back in WW1 and WW2 (as far as I'm aware) had rebreathers on board, they looked like life jackets but had a breathing mask, in, built carbon dioxide scrubbers and air canister. These would allow you to breath for enough time for the compartment to flood and escape to the surface with air to spare. Here is a picture of a rebreather used on U-boats.
<HR></BLOCKQUOTE>

As far as I know, those dispositives doesn't allow you to go deeper than 20 meters or so -let's say about 60 ft-, because the difference of pressure between your lungs and the surrounding waters may make impossible respiratory movements. Furthermore, a german study proved than is just imposible to breath air at atmospherical pressure if you're unde 1.8 meters of water -about 5.5 ft deep.

radsov

10-23-2004, 09:47 AM

<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by Jose.MaC:
<BLOCKQUOTE class="ip-ubbcode-quote">quote:<HR>Originally posted by radsov:
You don't need to hold your breath, all subs of all Navy's back in WW1 and WW2 (as far as I'm aware) had rebreathers on board, they looked like life jackets but had a breathing mask, in, built carbon dioxide scrubbers and air canister. These would allow you to breath for enough time for the compartment to flood and escape to the surface with air to spare. Here is a picture of a rebreather used on U-boats.
<HR></BLOCKQUOTE>

As far as I know, those dispositives doesn't allow you to go deeper than 20 meters or so -let's say about 60 ft-, because the difference of pressure between your lungs and the surrounding waters may make impossible respiratory movements. Furthermore, a german study proved than is just imposible to breath air at atmospherical pressure if you're unde 1.8 meters of water -about 5.5 ft deep. <HR></BLOCKQUOTE>

Wether they used them in the sub just prior to complete flooding (before max water pressure) and then used them on the way up once they could I don't know. However if you examine the picture there is a pressurized canistor of air (not oxygen) which would have aided the user to expand their lungs much as mondern scuba gear does.

These items were definitly used at greater depths than you 60ft as they were used in the evacuation of U534 at around 90 - 100ft. So they were of some use in some capacity. The exact details of how I don't know.