Deep thoughts and some questions

-
Cope

Cope

Fusing with fire
Joined
Oct 20, 2009
Messages
6,737
Reaction score
10,191
Location
San Jose, Ca.
The other day i was watching some documentary on something or other about deep ocean stuff. They show the obligatory shot of the ROV touch down and silt plumes up around the machine.


We've all seen it.


So pressure vs density?

Here is an excerpt from the wiki page on the Marinas trench.

At the bottom of the trench, the water column above exerts a pressure of 1,086 bars (15,750 psi), more than 1,071 times the standard atmospheric pressure at sea level. At this pressure, the density of water is increased by 4.96%.

[FONT=-apple-system, BlinkMacSystemFont, Segoe UI, Roboto, Lato, Helvetica, Arial, sans-serif]Those of us that have hydro locked an engine know water dosnt really compress much.
[/FONT]


[FONT=-apple-system, BlinkMacSystemFont, Segoe UI, Roboto, Lato, Helvetica, Arial, sans-serif]My question is this.

Shouldn't that silt have almost 16,000 pounds holding it down? Id think the ocean floor would be like a steel plate and everything smashed flat?

I know the pressure surrounds objects evenly and thats why we use spheres to get there but at some point there is no more "underneath" and the weight (pressure) should be pushing down?


Right now im watching a doc titled, "The Deadly Treasure of Lake Kivu."
It talks about this deep lake in africa that is holding ton and tons of methane under its water due to water density.


For some reason I can not wrap my brain around this.


Do ROVs use more power to cover a given distance at great depth due to water density?

Much like an aircraft burns more fuel the higher it flys due to reduced air density / lift.


Any one here a deep water scientist type?


Or just can explain in simple terms what I am not taking into account?


Thank you, next window please.





[/FONT]
 
If I understand what you are asking ...
the water the sub is displacing as it moves down is carrying the silt up .
In terms we can understand its like quench or swirl... all the water has the same density... if you drop a car into a tub of wet concrete it still swirls and splashes like water even though its far denser.
Did I miss your point ?
 
mbaird said:
If I understand what you are asking ...
the water the sub is displacing as it moves down is carrying the silt up .
In terms we can understand its like quench or swirl... all the water has the same density... if you drop a car into a tub of wet concrete it still swirls and splashes like water even though its far denser.
Did I miss your point ?
Click to expand...

Ok this is starting to help.


I think a big part of what i dont understand is pressure vs density

The water never gets any "thicker" but... and thats where i lose it.
 
Yeh, it all comes down to pressure equalization. I don't remember what the depth record for a man diving, without a submarine like capsule, so I'm talking about wet suit/ deep diving suit or bell. A bell subjects the man to the full pressure of the water, as it works by pumping air at high enough pressure to drive the water out the open bottom.

This is where nitrogen in the blood is a problem, and why divers must decompress.

A quick search shows a scuba record at over 1000 ft

https://www.guinnessworldrecords.co...epest-scuba-dive-at-more-than-1000-feet-60537

You have to be careful looking this up, tho......The Navy has a new type suit called an "atmospheric" suit which allows the diver to exist at "sea level" pressure. That record is about 2000 ft.

the old "traditional" deep sea suits with the huge brass helmet subjected the body to same pressure (ballooned air) as the see around them. By the way there are incidents of those killing people---when the air in /out system valves stuck / malfunctioned/ or were misadjusted, and when ascending, the reducing pressure of the sea could "balloon" the suit making it impossible to more your arms and adjust the valving. From there you got to wait until the suit exploded due to higher air pressure/ reducing sea pressure, and then.......you were done.

 
Last edited:
It seems as usual im just over thinking it.

Pressure has no affect on the silt in this example because the effect of the billowing silt is shown in the DENSITY of the water, not the pressure.

As the density is only increased by 5 percent the water is "thicker" but not enough to affect the hydrodynamics of a silt plume.

Ok.

I think I got it.


Now.


How the heck is all that gas trapped at the bottom of that lake? (I should probably un pause it and watch the last 40 min.)

:)
 
Cope said:
The other day i was watching some documentary on something or other about deep ocean stuff. They show the obligatory shot of the ROV touch down and silt plumes up around the machine.


We've all seen it.


So pressure vs density?

Here is an excerpt from the wiki page on the Marinas trench.

At the bottom of the trench, the water column above exerts a pressure of 1,086 bars (15,750 psi), more than 1,071 times the standard atmospheric pressure at sea level. At this pressure, the density of water is increased by 4.96%.

[FONT=-apple-system, BlinkMacSystemFont, Segoe UI, Roboto, Lato, Helvetica, Arial, sans-serif]Those of us that have hydro locked an engine know water dosnt really compress much.
[/FONT]


[FONT=-apple-system, BlinkMacSystemFont, Segoe UI, Roboto, Lato, Helvetica, Arial, sans-serif]My question is this.

Shouldn't that silt have almost 16,000 pounds holding it down? Id think the ocean floor would be like a steel plate and everything smashed flat?

I know the pressure surrounds objects evenly and thats why we use spheres to get there but at some point there is no more "underneath" and the weight (pressure) should be pushing down?


Right now im watching a doc titled, "The Deadly Treasure of Lake Kivu."
It talks about this deep lake in africa that is holding ton and tons of methane under its water due to water density.


For some reason I can not wrap my brain around this.


Do ROVs use more power to cover a given distance at great depth due to water density?

Much like an aircraft burns more fuel the higher it flys due to reduced air density / lift.


Any one here a deep water scientist type?


Or just can explain in simple terms what I am not taking into account?


Thank you, next window please.





[/FONT]
Click to expand...
The pressure isn’t only holding it down, it is pressurizing the substrate in every direction at once. It still behaves with the same laws of physics, only slower.

What I don’t get is my dumbass watching a documentary on NR1, a submarine built without Congress’s permission by Admiral Rickover, a submarine that has two front wheels on the bottom to drive on the ocean floor-was taught to me to be classified and the documentary is explaining a ‘Dukes of Hazard’ story and scenario where that boat went off of a deep cliff and CRASHED into a much deeper part of the ocean-& I can’t figure out how they lived.

Thatkind of pressure makes space exploration efforts appear to be child’s play. All the evil is trying to get into you at thousands of pounds per square inch, versus keeping air in and a little zoomy radiation from the belts.
 
Fluids move from places of higher pressure to places of lower pressure. So if something acts on a system, this can allow it to move.
 
Cope said:
The other day i was watching some documentary on something or other about deep ocean stuff. They show the obligatory shot of the ROV touch down and silt plumes up around the machine.


We've all seen it.


So pressure vs density?

Here is an excerpt from the wiki page on the Marinas trench.

At the bottom of the trench, the water column above exerts a pressure of 1,086 bars (15,750 psi), more than 1,071 times the standard atmospheric pressure at sea level. At this pressure, the density of water is increased by 4.96%.

[FONT=-apple-system, BlinkMacSystemFont, Segoe UI, Roboto, Lato, Helvetica, Arial, sans-serif]Those of us that have hydro locked an engine know water dosnt really compress much.
[/FONT]


[FONT=-apple-system, BlinkMacSystemFont, Segoe UI, Roboto, Lato, Helvetica, Arial, sans-serif]My question is this.

Shouldn't that silt have almost 16,000 pounds holding it down? Id think the ocean floor would be like a steel plate and everything smashed flat?

I know the pressure surrounds objects evenly and thats why we use spheres to get there but at some point there is no more "underneath" and the weight (pressure) should be pushing down?


Right now im watching a doc titled, "The Deadly Treasure of Lake Kivu."
It talks about this deep lake in africa that is holding ton and tons of methane under its water due to water density.


For some reason I can not wrap my brain around this.


Do ROVs use more power to cover a given distance at great depth due to water density?

Much like an aircraft burns more fuel the higher it flys due to reduced air density / lift.


Any one here a deep water scientist type?


Or just can explain in simple terms what I am not taking into account?


Thank you, next window please.





[/FONT]
Click to expand...
The pressure isn’t only holding it down, it is pressurizing the substrate in every direction at once. It still behaves with the same laws of physics, only slower.

What I don’t get is my dumbass watching a documentary on NR1, a submarine built without Congress’s permission by Admiral Rickover, a submarine that has two front wheels on the bottom to drive on the ocean floor-was taught to me to be classified and the documentary is explaining a ‘Dukes of Hazard’ story and scenario where that boat went off of a deep cliff and CRASHED into a much deeper part of the ocean-& I can’t figure out how they lived.

Thatkind of pressure makes space exploration efforts appear to be child’s play. All the evil is trying to get into you at thousands of pounds per square inch, versus keeping air in and a little zoomy radiation from the belts.
 
67Dart273 said:
Yeh, it all comes down to pressure equalization. I don't remember what the depth record for a man diving, without a submarine like capsule, so I'm talking about wet suit/ deep diving suit or bell. A bell subjects the man to the full pressure of the water, as it works by pumping air at high enough pressure to drive the water out the open bottom.

This is where nitrogen in the blood is a problem, and why divers must decompress.

A quick search shows a scuba record at over 1000 ft

https://www.guinnessworldrecords.co...epest-scuba-dive-at-more-than-1000-feet-60537
Click to expand...


I watched a very interesting doc on freediving a while ago.

It was on the record holder at the time and the theory is her husband murdered her while he was acting as her safety diver.

Im not super comfortable with the thought of being deep underwater.

Just thinking about it creeps me out a little.

There are some good hard suit videos on you tube.
Mostly oil rig welding but those boy go deep! (And see some WEIRD stuff)
 
It's like pounding on something with a 1" wood dowel rod, vs pounding on it with a 1" piece of steel Re-Bar. It still moves material at the end of the action.

Have done scuba diving, and every time you go down 30' that's another atmospheric pressure.

Have been down to 90' (3 atmospheres pressure) and the stilt still churns up the same as it does at 20' depth.

Too much of that silt churning up clouds up the visibility.

Like a 5 gallon bucket of thin mixed anti-freeze coolant that has sat for a week.
You try to pour the clean stuff off the top to save it, after a couple of tips with the bucket it's all clouded up again.
 
Much like an aircraft burns more fuel the higher it flys due to reduced air density / lift.

Not sure if this is what you meant to say/post but, an aircraft will burn less fuel the higher it flies.
 
Cope said:
I watched a very interesting doc on freediving a while ago.

It was on the record holder at the time and the theory is her husband murdered her while he was acting as her safety diver.

Im not super comfortable with the thought of being deep underwater.

Just thinking about it creeps me out a little.

There are some good hard suit videos on you tube.
Mostly oil rig welding but those boy go deep! (And see some WEIRD stuff)
Click to expand...
I saw that documentary too!
It made me claustrophobic and afraid of the ocean.
 
greymouser7 said:
The pressure isn’t only holding it down, it is pressurizing the substrate in every direction at once. It still behaves with the same laws of physics, only slower.

What I don’t get is my dumbass watching a documentary on NR1, a submarine built without Congress’s permission by Admiral Rickover, a submarine that has two front wheels on the bottom to drive on the ocean floor-was taught to me to be classified and the documentary is explaining a ‘Dukes of Hazard’ story and scenario where that boat went off of a deep cliff and CRASHED into a much deeper part of the ocean-& I can’t figure out how they lived.

Thatkind of pressure makes space exploration efforts appear to be child’s play. All the evil is trying to get into you at thousands of pounds per square inch, versus keeping air in and a little zoomy radiation from the belts.
Click to expand...


Before I clicked on this doc about the lake I almost re watched "AZORIAN". The doc about when tue CIA tried to rase that russian sub. That one is good.

Do you remember the name of the doc on that sub with wheels?

Id give that a watch.
 
coloradohill said:
Much like an aircraft burns more fuel the higher it flys due to reduced air density / lift.

Not sure if this is what you meant to say/post but, an aircraft will burn less fuel the higher it flies.
Click to expand...
Doesn’t the jet intake and ram induction negate much of the loss of atmospheric pressure?
 
Cope said:
Before I clicked on this doc about the lake I almost re watched "AZORIAN". The doc about when tue CIA tried to rase that russian sub. That one is good.

Do you remember the name of the doc on that sub with wheels?

Id give that a watch.
Click to expand...
The book Blindman’s bluff highlights all the best submarine stories, but it came out before the Kursk(?) blew up (I was deployed underwater when that happened), and a few dozen incidents have occurred since then. The San Francisco running into an uncharted underwater mountain (and we have the whole ocean mapped already soooo hmmmm.) and another sub a few weeks ago running into something in the China sea.

-I will search for the NR1 documentary and post it here.

the documentary where the wife died and the husband was suspect creeped me out a bit.
I would prefer a bullet or car crash or heart attack while just finishing sex…
 
coloradohill said:
Much like an aircraft burns more fuel the higher it flys due to reduced air density / lift.

Not sure if this is what you meant to say/post but, an aircraft will burn less fuel the higher it flies.
Click to expand...

I have no experience with full scale air craft so that could be wrong. I use to live at 6,500 above sea level. I also was heavy into flying model aircraft. (Remote control air planes and helicopters)

Most of the cheap "toy quality" stuff can not fly at altitude. They just cant move enough air over the wing to create lift. (Due to low air density)
The good "hobby grade" expensive stuff can fly. Not great but it can. Operating at those altitudes required running the engine at almost full speed to move enough air for flight.

Flight time are greatly reduced at altitude due to this.

I then moved down to sea lever and the same aircraft can hover or climb out at greatly reduced throttle.

Flight times are MUCH longer.

Also in tahoe i was involved heavily with the local airport. I did volunteer work and all sorts of stuff.

Most of the fatal accidents happen about 4 or 5 PM.

Pilots fly in and land early in good cold high density air. They get drunk, go ski and back at the airport by 5.

They now have so.e extra weight because they gonna take the mistress up and its hot. The air density has collapsed.

They pull full throttle and just never climb out. They fly right into the hill side.

So.

I ***-u-me that while the les dense air reduces drag the les dense air burns shitty and requires more oxidizer (fuel) to create the same amount of lift?


But like I said im not a pilot or a scientist. Im just a guy who is bored.

:)
 
Yeah for prop planes, air density is no joke, but his comment was about fuel consumption on a jet,and it is correct, I just wondered if with jet induction, at speed (300mph+) that air density regarding jet engine combustion was closer to irrelevant.
 
Well, it depends our course

If the earth is round, it takes less to travel at great depth because it's closer to the axis and therefore a short distance

If the earth is flat, it takes the same amount (untill it hits the wall or falls over the edge)
 
You must log in or register to reply here.
-

Back
Top