Scuba Quiz

[gamon]

yeah, but you're not going to have held your breath from the moment of the car impacting the water at the surface. you're going to keep breathing until you can't, i.e. the car has filled with water, which will be at depth, at pressure. this is a cesa situation and you'd better exhale on the way up!

In this scenario yes but the water is getting miuddied (pun intended) with the whole window open vs closed scenarios.

If the windows were fully or partially open and one of the earlier posters might have been responding to that before I edited it thanks to a subsequent post by @johndiver999 - then the car hits the water and the person takes one final gasp at the surface before the car submerges and drops to 50' in the time it takes them to get focused, get out of their seatbelt open their door (or squeeze through a partially opened window) to extricate themselves.

In which case there would be no risk of lung over expansion.

 

[johndiver999]

Related video....This looked really dangerous to put non-divers in this situation.

 

[TMHeimer]

If the windows are closed tight is the car a non-flexible container like a scuba tank? Not sure where this fits into the question, if at all. CAN a car be completely sealed closed?

 

[nolatom]

Drive a really tall car, where you sit way high up. Bottom is 50? Roof or top of door frame where your throat is, is more like what, 42 feet for your suddenly frightened lungs? That's doable.
Long ago my OW instructor said, "if you have to make a controlled (we hope) emergency ascent, do it, but say, or actually sing it, exhaling slowly while
saying "Aaaaaaahhhhhhhhhhh" all the way up.

I haven't had to use that advice, but I have remembered "as long as you can breathe, you can solve your other problems". Other gems too.

 

[wheeledgoat]

In this scenario yes but the water is getting miuddied (pun intended) with the whole window open vs closed scenarios.

If the windows were fully or partially open and one of the earlier posters might have been responding to that before I edited it thanks to a subsequent post by @johndiver999 - then the car hits the water and the person takes one final gasp at the surface before the car submerges and drops to 50' in the time it takes them to get focused, get out of their seatbelt open their door (or squeeze through a partially opened window) to extricate themselves.

In which case there would be no risk of lung over expansion.

if that hypothetical were possible, then yes - that last gasp would be at 1ATA

but let's get real - your car just veered off the road and plowed into water. you're all excited and jacked up, and you WILL NOT have the presence of mind to not breathe while your car submerges. further, I strongly doubt (with absolutely no data to back it up) that any car is perfectly sealed. even if all the seals around the doors and windows held, you still have the ventilation system and outside air intake. as you and your car descend into the water, the water and the air in the cabin pressurize accordingly.

 

[TMHeimer]

if that hypothetical were possible, then yes - that last gasp would be at 1ATA

but let's get real - your car just veered off the road and plowed into water. you're all excited and jacked up, and you WILL NOT have the presence of mind to not breathe while your car submerges. further, I strongly doubt (with absolutely no data to back it up) that any car is perfectly sealed. even if all the seals around the doors and windows held, you still have the ventilation system and outside air intake. as you and your car descend into the water, the water and the air in the cabin pressurize accordingly.

Agree. Even if you did take your last breath at the surface you wouldn't last until you returned to the surface on that breath. Damn seatbelts.

 

[Angelo Farina]

First of all I answer by personal experience: in 1980 I and my wife did perform this as part of a civil protection exercise.
We did drive an almost wrecked car inside a small lake. Of course we had air tanks between our legs, just for safety.
The windows were closed and it did take several minutes before the cockpit was full of water.
Until the cockpit was full it was impossible to open the doors, as the external pressure was keeping them locked.
Only when the water level was close to our mouth we were able to open the doors.
So we had necessarily to breath the air trapped in the cockpit. The hypothesis of holding the same breath from the surface is irrealistic, due to the long time before you can escape.
And of course before exiting the car we did take a last full breath, hence we had to exhale during the ascent, as normal.
The depth in our case was minimal, perhaps 3 or 4 meters.
The hard part of the exercise came later.
We had to dive for attaching ropes to the car wreck, and pull it out of the lake using an Unimog as a tractor.
The ropes were too short, so the driver of the Unimog had to enter water with the rear wheels for attaching the ropes. But the bottom was soft mud, and as the Unimog attempted to pull out the car, the rear wheels started excavating in the mud. The rear of the truck went down and down, and in the end we had TWO wrecks to be pulled out of the water...

 

[Jcp2]

First of all I answer by personal experience: in 1980 I and my wife did perform this as part of a civil protection exercise.
We did drive an almost wrecked car inside a small lake. Of course we had air tanks between our legs, just for safety.
The windows were closed and it did take several minutes before the cockpit was full of water.
Until the cockpit was full it was impossible to open the doors, as the external pressure was keeping them locked.
Only when the water level was close to our mouth we were able to open the doors.
So we had necessarily to breath the air trapped in the cockpit. The hypothesis of holding the same breath from the surface is irrealistic, due to the long time before you can escape.
And of course before exiting the car we did take a last full breath, hence we had to exhale during the ascent, as normal.
The depth in our case was minimal, perhaps 3 or 4 meters.
The hard part of the exercise came later.
We had to dive for attaching ropes to the car wreck, and pull it out of the lake using an Unimog as a tractor.
The ropes were too short, so the driver of the Unimog had to enter water with the rear wheels for attaching the ropes. But the bottom was soft mud, and as the Unimog attempted to pull out the car, the rear wheels started excavating in the mud. The rear of the truck went down and down, and in the end we had TWO wrecks to be pulled out of the water...

You’ve led quite an interesting life. This reminds me of the old chestnut about jumping up right before a runaway elevator hits the ground floor so you won’t be hurt.

 

[wheeledgoat]

First of all I answer by personal experience: in 1980 I and my wife did perform this as part of a civil protection exercise.
We did drive an almost wrecked car inside a small lake. Of course we had air tanks between our legs, just for safety.
The windows were closed and it did take several minutes before the cockpit was full of water.
Until the cockpit was full it was impossible to open the doors, as the external pressure was keeping them locked.
Only when the water level was close to our mouth we were able to open the doors.
So we had necessarily to breath the air trapped in the cockpit. The hypothesis of holding the same breath from the surface is irrealistic, due to the long time before you can escape.
And of course before exiting the car we did take a last full breath, hence we had to exhale during the ascent, as normal.
The depth in our case was minimal, perhaps 3 or 4 meters.
The hard part of the exercise came later.
We had to dive for attaching ropes to the car wreck, and pull it out of the lake using an Unimog as a tractor.
The ropes were too short, so the driver of the Unimog had to enter water with the rear wheels for attaching the ropes. But the bottom was soft mud, and as the Unimog attempted to pull out the car, the rear wheels started excavating in the mud. The rear of the truck went down and down, and in the end we had TWO wrecks to be pulled out of the water...

at the risk of comparing a television show to your real-life experience, I'll just say that a mythbusters episode completely confirmed your account of being unable to open doors until the car was mostly full of water. adam savage, an experienced diver (among many other things) recounted even that very controlled situation as quite challenging and terrifying.

after seeing that, I and everyone I care about keep one of those devices that will a) cut seatbelts and b) break glass in the car. currently I have one that is also a phone charger/portable battery backup and flashlight all rolled into one.

curious: did your car roll over once submerged like in the mythbusters episode?

 

[TMHeimer]

First of all I answer by personal experience: in 1980 I and my wife did perform this as part of a civil protection exercise.
We did drive an almost wrecked car inside a small lake. Of course we had air tanks between our legs, just for safety.
The windows were closed and it did take several minutes before the cockpit was full of water.
Until the cockpit was full it was impossible to open the doors, as the external pressure was keeping them locked.
Only when the water level was close to our mouth we were able to open the doors.
So we had necessarily to breath the air trapped in the cockpit. The hypothesis of holding the same breath from the surface is irrealistic, due to the long time before you can escape.
And of course before exiting the car we did take a last full breath, hence we had to exhale during the ascent, as normal.
The depth in our case was minimal, perhaps 3 or 4 meters.
The hard part of the exercise came later.
We had to dive for attaching ropes to the car wreck, and pull it out of the lake using an Unimog as a tractor.
The ropes were too short, so the driver of the Unimog had to enter water with the rear wheels for attaching the ropes. But the bottom was soft mud, and as the Unimog attempted to pull out the car, the rear wheels started excavating in the mud. The rear of the truck went down and down, and in the end we had TWO wrecks to be pulled out of the water...

Great stuff, thanks for the physics of it! Sounds like all you needed was a more solid lake bottom.