Cheap And Nasty Snorkel extension
 

Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?

Lloyd Sumpter
"Far Cove" Catalina 36

Cheap And Nasty Snorkel extension
 

It would be extremely dificult if not impossible to breath through a
hose at surface pressure if your lungs get more than 2 or 3 feet under
water. The difference at 3' is only about 1.5 pounds per square inch
but the water is pressing on a couple thousand square inches of lung
surface.

Lloyd Sumpter wrote:

Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?

Lloyd Sumpter
"Far Cove" Catalina 36


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Cheap And Nasty Snorkel extension
 

It would be extremely dificult if not impossible to breath through a
hose at surface pressure if your lungs get more than 2 or 3 feet under
water. The difference at 3' is only about 1.5 pounds per square inch
but the water is pressing on a couple thousand square inches of lung
surface.

Lloyd Sumpter wrote:

Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?

Lloyd Sumpter
"Far Cove" Catalina 36


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Cheap And Nasty Snorkel extension
 

That is a very dangerous idea but the reason why isn't immediately obvious.

When you exhale you will fill the long tube with your expelled air and then
breathe it all back in. I believe this would result in hypoxia (oxygen
deficiency) in which case you could drown without realizing what's
happening.

Snorkel tubes are short so most of the exhausted air is expelled and there
is enough of an influx of fresh air to avoid this problem.



"Lloyd Sumpter" wrote in message
...
Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?

Lloyd Sumpter
"Far Cove" Catalina 36

Cheap And Nasty Snorkel extension
 

That is a very dangerous idea but the reason why isn't immediately obvious.

When you exhale you will fill the long tube with your expelled air and then
breathe it all back in. I believe this would result in hypoxia (oxygen
deficiency) in which case you could drown without realizing what's
happening.

Snorkel tubes are short so most of the exhausted air is expelled and there
is enough of an influx of fresh air to avoid this problem.



"Lloyd Sumpter" wrote in message
...
Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?

Lloyd Sumpter
"Far Cove" Catalina 36

Cheap And Nasty Snorkel extension
 

Good point.

So you need to "in through the mouth out through the nose" or else get
a "proper" mouthpiece that expels the "out-breath" directly.

As for the pressure, that's a big question mark. At the prop, I'm only
under maybe a foot (depending on body position). I don't know if the
pressure would be too much for me to take a breath or not (it's easy for
me to create suction in my mouth at this depth, so...I donno.)

After all, look at all the Bad Movies that have Our Heros hiding
underwater with a reed in their mouths... ;)

Lloyd


On Mon, 03 Nov 2003 20:37:27 +0000, Paul wrote:

That is a very dangerous idea but the reason why isn't immediately obvious.

When you exhale you will fill the long tube with your expelled air and then
breathe it all back in. I believe this would result in hypoxia (oxygen
deficiency) in which case you could drown without realizing what's
happening.

Snorkel tubes are short so most of the exhausted air is expelled and there
is enough of an influx of fresh air to avoid this problem.



"Lloyd Sumpter" wrote in message
...
Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?

Lloyd Sumpter
"Far Cove" Catalina 36

Cheap And Nasty Snorkel extension
 

Good point.

So you need to "in through the mouth out through the nose" or else get
a "proper" mouthpiece that expels the "out-breath" directly.

As for the pressure, that's a big question mark. At the prop, I'm only
under maybe a foot (depending on body position). I don't know if the
pressure would be too much for me to take a breath or not (it's easy for
me to create suction in my mouth at this depth, so...I donno.)

After all, look at all the Bad Movies that have Our Heros hiding
underwater with a reed in their mouths... ;)

Lloyd


On Mon, 03 Nov 2003 20:37:27 +0000, Paul wrote:

That is a very dangerous idea but the reason why isn't immediately obvious.

When you exhale you will fill the long tube with your expelled air and then
breathe it all back in. I believe this would result in hypoxia (oxygen
deficiency) in which case you could drown without realizing what's
happening.

Snorkel tubes are short so most of the exhausted air is expelled and there
is enough of an influx of fresh air to avoid this problem.



"Lloyd Sumpter" wrote in message
...
Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?

Lloyd Sumpter
"Far Cove" Catalina 36

Cheap And Nasty Snorkel extension
 

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Mon, 03 Nov 2003 11:48:30 -0800,
Lloyd Sumpter wrote:
Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?


There are two problems.

1) Unless you have a seperate exhaust path (usually via a valve directly
into the water) you can't push the "bad" air, out of the snorkle very
far. If the volume of the snorkel tube is a significant fraction of your
lung volume, you just pusþ the air up the tube, and then draw that same
air, back into your lungs.

2) The pressure at say, 7 feet depth, is about 1.5 atmospheres, so you
will be drawing in 1 atmos air, against 1.5 atmos pressure on your
lungs. Try it. Take a garden hose down to 7 feet, with the other end in
the air, (of course, keeping the water out of it) and try taking a
breath through it. You will be able to do it, for a while, maybe a
minute, by exhaling through your nose, but you'll give your diaphram a
real workout.

The usual solution, is either a tank+reg with a really long hose in
between :) or a hookah setup. The tank's a lot cheaper, especially if
you allready have the tank and the regulator, the hose isn't too
expensive.


-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.3 (GNU/Linux)

iD8DBQE/pspKd90bcYOAWPYRAnD3AKDGpbObVHddXgw1m2JPkEb/+kz5JwCffVEL
TlnpigBCVJ4BVFSWbsmC0QI=
=Vful
-----END PGP SIGNATURE-----

--
Jim Richardson http://www.eskimo.com/~warlock
"What I look forward to is continued immaturity followed by death."
-- Dave Barry

Cheap And Nasty Snorkel extension
 

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Mon, 03 Nov 2003 11:48:30 -0800,
Lloyd Sumpter wrote:
Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?


There are two problems.

1) Unless you have a seperate exhaust path (usually via a valve directly
into the water) you can't push the "bad" air, out of the snorkle very
far. If the volume of the snorkel tube is a significant fraction of your
lung volume, you just pusþ the air up the tube, and then draw that same
air, back into your lungs.

2) The pressure at say, 7 feet depth, is about 1.5 atmospheres, so you
will be drawing in 1 atmos air, against 1.5 atmos pressure on your
lungs. Try it. Take a garden hose down to 7 feet, with the other end in
the air, (of course, keeping the water out of it) and try taking a
breath through it. You will be able to do it, for a while, maybe a
minute, by exhaling through your nose, but you'll give your diaphram a
real workout.

The usual solution, is either a tank+reg with a really long hose in
between :) or a hookah setup. The tank's a lot cheaper, especially if
you allready have the tank and the regulator, the hose isn't too
expensive.


-----BEGIN PGP SIGNATURE-----
Version: GnuPG v1.2.3 (GNU/Linux)

iD8DBQE/pspKd90bcYOAWPYRAnD3AKDGpbObVHddXgw1m2JPkEb/+kz5JwCffVEL
TlnpigBCVJ4BVFSWbsmC0QI=
=Vful
-----END PGP SIGNATURE-----

--
Jim Richardson http://www.eskimo.com/~warlock
"What I look forward to is continued immaturity followed by death."
-- Dave Barry

Cheap And Nasty Snorkel extension
 

Go try it in a swimming pool with a garden hose before you get yourself
hung up under your keel and get nominated for a Darwin Award. You will
find that it is impossible to breath if your lungs get more than about
3' deep.

Your prop is probably a foot or two deep minimum and if you are upright
your lungs will be a foot or two below that. You might be able to do it
upside down and sort of lay against the hull so your lungs are not as
deep. Hang your belly button on a barnicle to keep in place. Better
use red bottom paint so the blood stains won't show as bad. :-)

Movie cowboys hid from the indians with a reed by laying on their backs
so their body is just below the surface. About the same as normal
snorkling depth. It also helped to be solid muscle. Beer guts float. :-)


Lloyd Sumpter wrote:
Good point.

So you need to "in through the mouth out through the nose" or else get
a "proper" mouthpiece that expels the "out-breath" directly.

As for the pressure, that's a big question mark. At the prop, I'm only
under maybe a foot (depending on body position). I don't know if the
pressure would be too much for me to take a breath or not (it's easy for
me to create suction in my mouth at this depth, so...I donno.)

After all, look at all the Bad Movies that have Our Heros hiding
underwater with a reed in their mouths... ;)

Lloyd


On Mon, 03 Nov 2003 20:37:27 +0000, Paul wrote:


That is a very dangerous idea but the reason why isn't immediately obvious.

When you exhale you will fill the long tube with your expelled air and then
breathe it all back in. I believe this would result in hypoxia (oxygen
deficiency) in which case you could drown without realizing what's
happening.

Snorkel tubes are short so most of the exhausted air is expelled and there
is enough of an influx of fresh air to avoid this problem.



"Lloyd Sumpter" wrote in message
.. .

Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?

Lloyd Sumpter
"Far Cove" Catalina 36




--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Cheap And Nasty Snorkel extension
 

Go try it in a swimming pool with a garden hose before you get yourself
hung up under your keel and get nominated for a Darwin Award. You will
find that it is impossible to breath if your lungs get more than about
3' deep.

Your prop is probably a foot or two deep minimum and if you are upright
your lungs will be a foot or two below that. You might be able to do it
upside down and sort of lay against the hull so your lungs are not as
deep. Hang your belly button on a barnicle to keep in place. Better
use red bottom paint so the blood stains won't show as bad. :-)

Movie cowboys hid from the indians with a reed by laying on their backs
so their body is just below the surface. About the same as normal
snorkling depth. It also helped to be solid muscle. Beer guts float. :-)


Lloyd Sumpter wrote:
Good point.

So you need to "in through the mouth out through the nose" or else get
a "proper" mouthpiece that expels the "out-breath" directly.

As for the pressure, that's a big question mark. At the prop, I'm only
under maybe a foot (depending on body position). I don't know if the
pressure would be too much for me to take a breath or not (it's easy for
me to create suction in my mouth at this depth, so...I donno.)

After all, look at all the Bad Movies that have Our Heros hiding
underwater with a reed in their mouths... ;)

Lloyd


On Mon, 03 Nov 2003 20:37:27 +0000, Paul wrote:


That is a very dangerous idea but the reason why isn't immediately obvious.

When you exhale you will fill the long tube with your expelled air and then
breathe it all back in. I believe this would result in hypoxia (oxygen
deficiency) in which case you could drown without realizing what's
happening.

Snorkel tubes are short so most of the exhausted air is expelled and there
is enough of an influx of fresh air to avoid this problem.



"Lloyd Sumpter" wrote in message
.. .

Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?

Lloyd Sumpter
"Far Cove" Catalina 36




--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Cheap And Nasty Snorkel extension
 

On Mon, 03 Nov 2003 13:36:10 +0000, Jim Richardson wrote:

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Mon, 03 Nov 2003 11:48:30 -0800,
Lloyd Sumpter wrote:
Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?


There are two problems.

1) Unless you have a seperate exhaust path (usually via a valve directly
into the water) you can't push the "bad" air, out of the snorkle very
far. If the volume of the snorkel tube is a significant fraction of your
lung volume, you just pusþ the air up the tube, and then draw that same
air, back into your lungs.

2) The pressure at say, 7 feet depth, is about 1.5 atmospheres, so you
will be drawing in 1 atmos air, against 1.5 atmos pressure on your
lungs. Try it. Take a garden hose down to 7 feet, with the other end in
the air, (of course, keeping the water out of it) and try taking a
breath through it. You will be able to do it, for a while, maybe a
minute, by exhaling through your nose, but you'll give your diaphram a
real workout.

The usual solution, is either a tank+reg with a really long hose in
between :) or a hookah setup. The tank's a lot cheaper, especially if
you allready have the tank and the regulator, the hose isn't too
expensive.


I'm guessing most of the respondents here have never "snorkel-dove" (ie
mask, fins, hold your breath) to do prop/rudder repairs, etc.

(long tube problem covered elsewhere - ie to exhale separately)

- A lungful of air pins you pretty tight onto the hull - there's NO
WAY you're "upright" or anywhere near 7 ft deep.

- (from another response) if you're gonna get hooked on the keel with an
"air tube", you will snorkel-diving as well, and in the latter case you
have NO air! Pinned to the hull, it's pretty easy to push off and get to
the surface.

- Um...if I had a tank and regulator, why not just put it on?

So I guess, Updated Question: How DO you do "maintenance" on your prop,
rudder, etc. underwater? "Snorkel-dive"? Scuba? Pay someone else? Survey
says...

Lloyd Sumpter
"Far Cove" Catalina 36 - put me down for "snorkel-dive"

Cheap And Nasty Snorkel extension
 

On Mon, 03 Nov 2003 13:36:10 +0000, Jim Richardson wrote:

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

On Mon, 03 Nov 2003 11:48:30 -0800,
Lloyd Sumpter wrote:
Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?


There are two problems.

1) Unless you have a seperate exhaust path (usually via a valve directly
into the water) you can't push the "bad" air, out of the snorkle very
far. If the volume of the snorkel tube is a significant fraction of your
lung volume, you just pusþ the air up the tube, and then draw that same
air, back into your lungs.

2) The pressure at say, 7 feet depth, is about 1.5 atmospheres, so you
will be drawing in 1 atmos air, against 1.5 atmos pressure on your
lungs. Try it. Take a garden hose down to 7 feet, with the other end in
the air, (of course, keeping the water out of it) and try taking a
breath through it. You will be able to do it, for a while, maybe a
minute, by exhaling through your nose, but you'll give your diaphram a
real workout.

The usual solution, is either a tank+reg with a really long hose in
between :) or a hookah setup. The tank's a lot cheaper, especially if
you allready have the tank and the regulator, the hose isn't too
expensive.


I'm guessing most of the respondents here have never "snorkel-dove" (ie
mask, fins, hold your breath) to do prop/rudder repairs, etc.

(long tube problem covered elsewhere - ie to exhale separately)

- A lungful of air pins you pretty tight onto the hull - there's NO
WAY you're "upright" or anywhere near 7 ft deep.

- (from another response) if you're gonna get hooked on the keel with an
"air tube", you will snorkel-diving as well, and in the latter case you
have NO air! Pinned to the hull, it's pretty easy to push off and get to
the surface.

- Um...if I had a tank and regulator, why not just put it on?

So I guess, Updated Question: How DO you do "maintenance" on your prop,
rudder, etc. underwater? "Snorkel-dive"? Scuba? Pay someone else? Survey
says...

Lloyd Sumpter
"Far Cove" Catalina 36 - put me down for "snorkel-dive"

Cheap And Nasty Snorkel extension
 

Jim Richardson wrote:


2) The pressure at say, 7 feet depth, is about 1.5 atmospheres,

The pressure at say, 7 feet depth, (in seawater) is about 3 psig. It
would take another 9 feet to reach 1.5 ats.

Seawater pressure increases at around .445 psig per foot.

Rick

Cheap And Nasty Snorkel extension
 

Jim Richardson wrote:


2) The pressure at say, 7 feet depth, is about 1.5 atmospheres,

The pressure at say, 7 feet depth, (in seawater) is about 3 psig. It
would take another 9 feet to reach 1.5 ats.

Seawater pressure increases at around .445 psig per foot.

Rick

Cheap And Nasty Snorkel extension
 

One atmosphere of pressure (14.7 psi) is 33 feet of seawater. THe .445
is correct but your math is wrong. 1.5 atmospheres would be about 50
feet. Regardless, the normal pressure differential that our lungs
produce is about 12 millibar or .17 psi. A person in very good health
can inhale at a maximum pressure differential of about 100 milibars or
1.45 psi. That is about 39 inches of seawater.

Just to verify the figures I went out to the boat shed, cranked up the
vacuum system and tried to breathe from the vacuum tube. I couldn't get
any air after 1.3 psi but I have probably inhaled more than my share of
Cabosil.



Rick wrote:

Jim Richardson wrote:


2) The pressure at say, 7 feet depth, is about 1.5 atmospheres,


The pressure at say, 7 feet depth, (in seawater) is about 3 psig. It
would take another 9 feet to reach 1.5 ats.

Seawater pressure increases at around .445 psig per foot.

Rick


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Cheap And Nasty Snorkel extension
 

One atmosphere of pressure (14.7 psi) is 33 feet of seawater. THe .445
is correct but your math is wrong. 1.5 atmospheres would be about 50
feet. Regardless, the normal pressure differential that our lungs
produce is about 12 millibar or .17 psi. A person in very good health
can inhale at a maximum pressure differential of about 100 milibars or
1.45 psi. That is about 39 inches of seawater.

Just to verify the figures I went out to the boat shed, cranked up the
vacuum system and tried to breathe from the vacuum tube. I couldn't get
any air after 1.3 psi but I have probably inhaled more than my share of
Cabosil.



Rick wrote:

Jim Richardson wrote:


2) The pressure at say, 7 feet depth, is about 1.5 atmospheres,


The pressure at say, 7 feet depth, (in seawater) is about 3 psig. It
would take another 9 feet to reach 1.5 ats.

Seawater pressure increases at around .445 psig per foot.

Rick


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Cheap And Nasty Snorkel extension
 

"Lloyd Sumpter" wrote in message .. .
Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?

Lloyd Sumpter
"Far Cove" Catalina 36

Because if water got into the top end, it would exert a pressure on
your lungs of about .5 psi/ft of depth. So if you are 10' down, it
would exert a pressure of 5 psi above atmospheric pressure.

Cheap And Nasty Snorkel extension
 

"Lloyd Sumpter" wrote in message .. .
Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?

Lloyd Sumpter
"Far Cove" Catalina 36

Because if water got into the top end, it would exert a pressure on
your lungs of about .5 psi/ft of depth. So if you are 10' down, it
would exert a pressure of 5 psi above atmospheric pressure.

Cheap And Nasty Snorkel extension
 

One atmosphere is sea level. Pressure of 14.7psi is the air pressure at sea
level. Kinda makes sense, if it was the pressure at 33 feet below sea level
then they wouldn't have called it an "atmosphere".

At 33 feet you are now subject to one additional atmosphere for a total of
two.

1.5 atmospheres is experienced at ~16 feet.


"Glenn Ashmore" wrote in message
news:F5Cpb.875$62.52@lakeread04...
One atmosphere of pressure (14.7 psi) is 33 feet of seawater. THe .445
is correct but your math is wrong. 1.5 atmospheres would be about 50
feet. Regardless, the normal pressure differential that our lungs
produce is about 12 millibar or .17 psi. A person in very good health
can inhale at a maximum pressure differential of about 100 milibars or
1.45 psi. That is about 39 inches of seawater.

Just to verify the figures I went out to the boat shed, cranked up the
vacuum system and tried to breathe from the vacuum tube. I couldn't get
any air after 1.3 psi but I have probably inhaled more than my share of
Cabosil.



Rick wrote:

Jim Richardson wrote:


2) The pressure at say, 7 feet depth, is about 1.5 atmospheres,


The pressure at say, 7 feet depth, (in seawater) is about 3 psig. It
would take another 9 feet to reach 1.5 ats.

Seawater pressure increases at around .445 psig per foot.

Rick


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Cheap And Nasty Snorkel extension
 

One atmosphere is sea level. Pressure of 14.7psi is the air pressure at sea
level. Kinda makes sense, if it was the pressure at 33 feet below sea level
then they wouldn't have called it an "atmosphere".

At 33 feet you are now subject to one additional atmosphere for a total of
two.

1.5 atmospheres is experienced at ~16 feet.


"Glenn Ashmore" wrote in message
news:F5Cpb.875$62.52@lakeread04...
One atmosphere of pressure (14.7 psi) is 33 feet of seawater. THe .445
is correct but your math is wrong. 1.5 atmospheres would be about 50
feet. Regardless, the normal pressure differential that our lungs
produce is about 12 millibar or .17 psi. A person in very good health
can inhale at a maximum pressure differential of about 100 milibars or
1.45 psi. That is about 39 inches of seawater.

Just to verify the figures I went out to the boat shed, cranked up the
vacuum system and tried to breathe from the vacuum tube. I couldn't get
any air after 1.3 psi but I have probably inhaled more than my share of
Cabosil.



Rick wrote:

Jim Richardson wrote:


2) The pressure at say, 7 feet depth, is about 1.5 atmospheres,


The pressure at say, 7 feet depth, (in seawater) is about 3 psig. It
would take another 9 feet to reach 1.5 ats.

Seawater pressure increases at around .445 psig per foot.

Rick


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Cheap And Nasty Snorkel extension
 

I'm sorry but that's not correct. At least according to when I was taught
dive physics. One atmosphere of pressure is every 33 feet of sea water. At
sea level, above the surface of the water you are at one atmosphere of
pressure. Zero atmospheres of pressure would be a vacum. As you descend in
salt water (it's slightly different in fresh water but not by much) to a
depth of 33 feet you're at two atmospheres of pressure, 66 feet equals 3
atmospheres, 99 feet 4 atmospheres etc.... 1.5 atmospheres of pressure is
16.5 feet of sea water.


Jerry




"Glenn Ashmore" wrote in message
news:F5Cpb.875$62.52@lakeread04...
One atmosphere of pressure (14.7 psi) is 33 feet of seawater. THe .445
is correct but your math is wrong. 1.5 atmospheres would be about 50
feet. Regardless, the normal pressure differential that our lungs
produce is about 12 millibar or .17 psi. A person in very good health
can inhale at a maximum pressure differential of about 100 milibars or
1.45 psi. That is about 39 inches of seawater.

Just to verify the figures I went out to the boat shed, cranked up the
vacuum system and tried to breathe from the vacuum tube. I couldn't get
any air after 1.3 psi but I have probably inhaled more than my share of
Cabosil.



Rick wrote:

Jim Richardson wrote:


2) The pressure at say, 7 feet depth, is about 1.5 atmospheres,


The pressure at say, 7 feet depth, (in seawater) is about 3 psig. It
would take another 9 feet to reach 1.5 ats.

Seawater pressure increases at around .445 psig per foot.

Rick


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Cheap And Nasty Snorkel extension
 

I'm sorry but that's not correct. At least according to when I was taught
dive physics. One atmosphere of pressure is every 33 feet of sea water. At
sea level, above the surface of the water you are at one atmosphere of
pressure. Zero atmospheres of pressure would be a vacum. As you descend in
salt water (it's slightly different in fresh water but not by much) to a
depth of 33 feet you're at two atmospheres of pressure, 66 feet equals 3
atmospheres, 99 feet 4 atmospheres etc.... 1.5 atmospheres of pressure is
16.5 feet of sea water.


Jerry




"Glenn Ashmore" wrote in message
news:F5Cpb.875$62.52@lakeread04...
One atmosphere of pressure (14.7 psi) is 33 feet of seawater. THe .445
is correct but your math is wrong. 1.5 atmospheres would be about 50
feet. Regardless, the normal pressure differential that our lungs
produce is about 12 millibar or .17 psi. A person in very good health
can inhale at a maximum pressure differential of about 100 milibars or
1.45 psi. That is about 39 inches of seawater.

Just to verify the figures I went out to the boat shed, cranked up the
vacuum system and tried to breathe from the vacuum tube. I couldn't get
any air after 1.3 psi but I have probably inhaled more than my share of
Cabosil.



Rick wrote:

Jim Richardson wrote:


2) The pressure at say, 7 feet depth, is about 1.5 atmospheres,


The pressure at say, 7 feet depth, (in seawater) is about 3 psig. It
would take another 9 feet to reach 1.5 ats.

Seawater pressure increases at around .445 psig per foot.

Rick


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Cheap And Nasty Snorkel extension
 

You guys don't seem to concieve the problem. We are NOT talking
absolute pressure here. Nitrogen absorption is not an issue. The
DIFFERENTIAL pressure is what we need to look at. The other end of the
hose is at one atmosphere not a vacuum and the lungs are at some higher
pressure. The lungs have to overcome the difference in pressure and
they will not be able to do so below about 40" of depth.

Debbie Griggs wrote:
I'm sorry but that's not correct. At least according to when I was taught
dive physics. One atmosphere of pressure is every 33 feet of sea water. At
sea level, above the surface of the water you are at one atmosphere of
pressure. Zero atmospheres of pressure would be a vacum. As you descend in
salt water (it's slightly different in fresh water but not by much) to a
depth of 33 feet you're at two atmospheres of pressure, 66 feet equals 3
atmospheres, 99 feet 4 atmospheres etc.... 1.5 atmospheres of pressure is
16.5 feet of sea water.


Jerry




"Glenn Ashmore" wrote in message
news:F5Cpb.875$62.52@lakeread04...

One atmosphere of pressure (14.7 psi) is 33 feet of seawater. THe .445
is correct but your math is wrong. 1.5 atmospheres would be about 50
feet. Regardless, the normal pressure differential that our lungs
produce is about 12 millibar or .17 psi. A person in very good health
can inhale at a maximum pressure differential of about 100 milibars or
1.45 psi. That is about 39 inches of seawater.

Just to verify the figures I went out to the boat shed, cranked up the
vacuum system and tried to breathe from the vacuum tube. I couldn't get
any air after 1.3 psi but I have probably inhaled more than my share of
Cabosil.



Rick wrote:


Jim Richardson wrote:



2) The pressure at say, 7 feet depth, is about 1.5 atmospheres,


The pressure at say, 7 feet depth, (in seawater) is about 3 psig. It
would take another 9 feet to reach 1.5 ats.

Seawater pressure increases at around .445 psig per foot.

Rick


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com





--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Cheap And Nasty Snorkel extension
 

You guys don't seem to concieve the problem. We are NOT talking
absolute pressure here. Nitrogen absorption is not an issue. The
DIFFERENTIAL pressure is what we need to look at. The other end of the
hose is at one atmosphere not a vacuum and the lungs are at some higher
pressure. The lungs have to overcome the difference in pressure and
they will not be able to do so below about 40" of depth.

Debbie Griggs wrote:
I'm sorry but that's not correct. At least according to when I was taught
dive physics. One atmosphere of pressure is every 33 feet of sea water. At
sea level, above the surface of the water you are at one atmosphere of
pressure. Zero atmospheres of pressure would be a vacum. As you descend in
salt water (it's slightly different in fresh water but not by much) to a
depth of 33 feet you're at two atmospheres of pressure, 66 feet equals 3
atmospheres, 99 feet 4 atmospheres etc.... 1.5 atmospheres of pressure is
16.5 feet of sea water.


Jerry




"Glenn Ashmore" wrote in message
news:F5Cpb.875$62.52@lakeread04...

One atmosphere of pressure (14.7 psi) is 33 feet of seawater. THe .445
is correct but your math is wrong. 1.5 atmospheres would be about 50
feet. Regardless, the normal pressure differential that our lungs
produce is about 12 millibar or .17 psi. A person in very good health
can inhale at a maximum pressure differential of about 100 milibars or
1.45 psi. That is about 39 inches of seawater.

Just to verify the figures I went out to the boat shed, cranked up the
vacuum system and tried to breathe from the vacuum tube. I couldn't get
any air after 1.3 psi but I have probably inhaled more than my share of
Cabosil.



Rick wrote:


Jim Richardson wrote:



2) The pressure at say, 7 feet depth, is about 1.5 atmospheres,


The pressure at say, 7 feet depth, (in seawater) is about 3 psig. It
would take another 9 feet to reach 1.5 ats.

Seawater pressure increases at around .445 psig per foot.

Rick


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com





--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Cheap And Nasty Snorkel extension
 

My point had nothing to do with differential pressure. I don't care if
someone can breathe with the difference in pressure at 40" depth. I honestly
don't.

I was simply pointing out that this statement:

One atmosphere of pressure (14.7 psi) is 33 feet of seawater

was incorrect.

That's all. Nothing more. Really.


"Glenn Ashmore" wrote in message
news:j4Dpb.880$62.544@lakeread04...
You guys don't seem to concieve the problem. We are NOT talking
absolute pressure here. Nitrogen absorption is not an issue. The
DIFFERENTIAL pressure is what we need to look at. The other end of the
hose is at one atmosphere not a vacuum and the lungs are at some higher
pressure. The lungs have to overcome the difference in pressure and
they will not be able to do so below about 40" of depth.

Debbie Griggs wrote:
I'm sorry but that's not correct. At least according to when I was
taught
dive physics. One atmosphere of pressure is every 33 feet of sea water.
At
sea level, above the surface of the water you are at one atmosphere of
pressure. Zero atmospheres of pressure would be a vacum. As you descend
in
salt water (it's slightly different in fresh water but not by much) to a
depth of 33 feet you're at two atmospheres of pressure, 66 feet equals 3
atmospheres, 99 feet 4 atmospheres etc.... 1.5 atmospheres of pressure
is
16.5 feet of sea water.


Jerry




"Glenn Ashmore" wrote in message
news:F5Cpb.875$62.52@lakeread04...

One atmosphere of pressure (14.7 psi) is 33 feet of seawater. THe .445
is correct but your math is wrong. 1.5 atmospheres would be about 50
feet. Regardless, the normal pressure differential that our lungs
produce is about 12 millibar or .17 psi. A person in very good health
can inhale at a maximum pressure differential of about 100 milibars or
1.45 psi. That is about 39 inches of seawater.

Just to verify the figures I went out to the boat shed, cranked up the
vacuum system and tried to breathe from the vacuum tube. I couldn't get
any air after 1.3 psi but I have probably inhaled more than my share of
Cabosil.



Rick wrote:


Jim Richardson wrote:



2) The pressure at say, 7 feet depth, is about 1.5 atmospheres,


The pressure at say, 7 feet depth, (in seawater) is about 3 psig. It
would take another 9 feet to reach 1.5 ats.

Seawater pressure increases at around .445 psig per foot.

Rick


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com





--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Cheap And Nasty Snorkel extension
 

My point had nothing to do with differential pressure. I don't care if
someone can breathe with the difference in pressure at 40" depth. I honestly
don't.

I was simply pointing out that this statement:

One atmosphere of pressure (14.7 psi) is 33 feet of seawater

was incorrect.

That's all. Nothing more. Really.


"Glenn Ashmore" wrote in message
news:j4Dpb.880$62.544@lakeread04...
You guys don't seem to concieve the problem. We are NOT talking
absolute pressure here. Nitrogen absorption is not an issue. The
DIFFERENTIAL pressure is what we need to look at. The other end of the
hose is at one atmosphere not a vacuum and the lungs are at some higher
pressure. The lungs have to overcome the difference in pressure and
they will not be able to do so below about 40" of depth.

Debbie Griggs wrote:
I'm sorry but that's not correct. At least according to when I was
taught
dive physics. One atmosphere of pressure is every 33 feet of sea water.
At
sea level, above the surface of the water you are at one atmosphere of
pressure. Zero atmospheres of pressure would be a vacum. As you descend
in
salt water (it's slightly different in fresh water but not by much) to a
depth of 33 feet you're at two atmospheres of pressure, 66 feet equals 3
atmospheres, 99 feet 4 atmospheres etc.... 1.5 atmospheres of pressure
is
16.5 feet of sea water.


Jerry




"Glenn Ashmore" wrote in message
news:F5Cpb.875$62.52@lakeread04...

One atmosphere of pressure (14.7 psi) is 33 feet of seawater. THe .445
is correct but your math is wrong. 1.5 atmospheres would be about 50
feet. Regardless, the normal pressure differential that our lungs
produce is about 12 millibar or .17 psi. A person in very good health
can inhale at a maximum pressure differential of about 100 milibars or
1.45 psi. That is about 39 inches of seawater.

Just to verify the figures I went out to the boat shed, cranked up the
vacuum system and tried to breathe from the vacuum tube. I couldn't get
any air after 1.3 psi but I have probably inhaled more than my share of
Cabosil.



Rick wrote:


Jim Richardson wrote:



2) The pressure at say, 7 feet depth, is about 1.5 atmospheres,


The pressure at say, 7 feet depth, (in seawater) is about 3 psig. It
would take another 9 feet to reach 1.5 ats.

Seawater pressure increases at around .445 psig per foot.

Rick


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com





--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Cheap And Nasty Snorkel extension
 

Then we are both correct. You were talking about PSIA (absolute) and I
was talking PSIG (Gage or relative to atmospheric).

In the context of this thread however, I made the more correct
application of the terminology.

Paul wrote:

My point had nothing to do with differential pressure. I don't care if
someone can breathe with the difference in pressure at 40" depth. I honestly
don't.

I was simply pointing out that this statement:


One atmosphere of pressure (14.7 psi) is 33 feet of seawater


was incorrect.

That's all. Nothing more. Really.


"Glenn Ashmore" wrote in message
news:j4Dpb.880$62.544@lakeread04...

You guys don't seem to concieve the problem. We are NOT talking
absolute pressure here. Nitrogen absorption is not an issue. The
DIFFERENTIAL pressure is what we need to look at. The other end of the
hose is at one atmosphere not a vacuum and the lungs are at some higher
pressure. The lungs have to overcome the difference in pressure and
they will not be able to do so below about 40" of depth.

Debbie Griggs wrote:

I'm sorry but that's not correct. At least according to when I was

taught

dive physics. One atmosphere of pressure is every 33 feet of sea water.

At

sea level, above the surface of the water you are at one atmosphere of
pressure. Zero atmospheres of pressure would be a vacum. As you descend

in

salt water (it's slightly different in fresh water but not by much) to a
depth of 33 feet you're at two atmospheres of pressure, 66 feet equals 3
atmospheres, 99 feet 4 atmospheres etc.... 1.5 atmospheres of pressure

is

16.5 feet of sea water.


Jerry




"Glenn Ashmore" wrote in message
news:F5Cpb.875$62.52@lakeread04...


One atmosphere of pressure (14.7 psi) is 33 feet of seawater. THe .445
is correct but your math is wrong. 1.5 atmospheres would be about 50
feet. Regardless, the normal pressure differential that our lungs
produce is about 12 millibar or .17 psi. A person in very good health
can inhale at a maximum pressure differential of about 100 milibars or
1.45 psi. That is about 39 inches of seawater.

Just to verify the figures I went out to the boat shed, cranked up the
vacuum system and tried to breathe from the vacuum tube. I couldn't get
any air after 1.3 psi but I have probably inhaled more than my share of
Cabosil.



Rick wrote:



Jim Richardson wrote:




2) The pressure at say, 7 feet depth, is about 1.5 atmospheres,


The pressure at say, 7 feet depth, (in seawater) is about 3 psig. It
would take another 9 feet to reach 1.5 ats.

Seawater pressure increases at around .445 psig per foot.

Rick


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com




--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com





--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Cheap And Nasty Snorkel extension
 

Then we are both correct. You were talking about PSIA (absolute) and I
was talking PSIG (Gage or relative to atmospheric).

In the context of this thread however, I made the more correct
application of the terminology.

Paul wrote:

My point had nothing to do with differential pressure. I don't care if
someone can breathe with the difference in pressure at 40" depth. I honestly
don't.

I was simply pointing out that this statement:


One atmosphere of pressure (14.7 psi) is 33 feet of seawater


was incorrect.

That's all. Nothing more. Really.


"Glenn Ashmore" wrote in message
news:j4Dpb.880$62.544@lakeread04...

You guys don't seem to concieve the problem. We are NOT talking
absolute pressure here. Nitrogen absorption is not an issue. The
DIFFERENTIAL pressure is what we need to look at. The other end of the
hose is at one atmosphere not a vacuum and the lungs are at some higher
pressure. The lungs have to overcome the difference in pressure and
they will not be able to do so below about 40" of depth.

Debbie Griggs wrote:

I'm sorry but that's not correct. At least according to when I was

taught

dive physics. One atmosphere of pressure is every 33 feet of sea water.

At

sea level, above the surface of the water you are at one atmosphere of
pressure. Zero atmospheres of pressure would be a vacum. As you descend

in

salt water (it's slightly different in fresh water but not by much) to a
depth of 33 feet you're at two atmospheres of pressure, 66 feet equals 3
atmospheres, 99 feet 4 atmospheres etc.... 1.5 atmospheres of pressure

is

16.5 feet of sea water.


Jerry




"Glenn Ashmore" wrote in message
news:F5Cpb.875$62.52@lakeread04...


One atmosphere of pressure (14.7 psi) is 33 feet of seawater. THe .445
is correct but your math is wrong. 1.5 atmospheres would be about 50
feet. Regardless, the normal pressure differential that our lungs
produce is about 12 millibar or .17 psi. A person in very good health
can inhale at a maximum pressure differential of about 100 milibars or
1.45 psi. That is about 39 inches of seawater.

Just to verify the figures I went out to the boat shed, cranked up the
vacuum system and tried to breathe from the vacuum tube. I couldn't get
any air after 1.3 psi but I have probably inhaled more than my share of
Cabosil.



Rick wrote:



Jim Richardson wrote:




2) The pressure at say, 7 feet depth, is about 1.5 atmospheres,


The pressure at say, 7 feet depth, (in seawater) is about 3 psig. It
would take another 9 feet to reach 1.5 ats.

Seawater pressure increases at around .445 psig per foot.

Rick


--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com




--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com





--
Glenn Ashmore

I'm building a 45' cutter in strip/composite. Watch my progress (or lack
there of) at: http://www.rutuonline.com
Shameless Commercial Division: http://www.spade-anchor-us.com

Cheap And Nasty Snorkel extension
 

Rick wrote in message link.net...
Jim Richardson wrote:


2) The pressure at say, 7 feet depth, is about 1.5 atmospheres,

The pressure at say, 7 feet depth, (in seawater) is about 3 psig. It
would take another 9 feet to reach 1.5 ats.

Seawater pressure increases at around .445 psig per foot.

Rick

I do use a mask and snorkel to work on my prop. I even use it to work
on my keel and I just dive down and hold my breath. Its not a
problem. Sometimes when I dont want to dive down, I use a long
handled edging tool to reach the keel, works for the prop too.

Cheap And Nasty Snorkel extension
 

Rick wrote in message link.net...
Jim Richardson wrote:


2) The pressure at say, 7 feet depth, is about 1.5 atmospheres,

The pressure at say, 7 feet depth, (in seawater) is about 3 psig. It
would take another 9 feet to reach 1.5 ats.

Seawater pressure increases at around .445 psig per foot.

Rick

I do use a mask and snorkel to work on my prop. I even use it to work
on my keel and I just dive down and hold my breath. Its not a
problem. Sometimes when I dont want to dive down, I use a long
handled edging tool to reach the keel, works for the prop too.

Cheap And Nasty Snorkel extension
 

I've wondered about the small bottles of compressed air complete with a
mouthpiece that emergency crews might carry.
Not sure if they are for 'fire' use or to revive a patient.
Could they be used for Lloyd's application?

Cheap And Nasty Snorkel extension
 

I've wondered about the small bottles of compressed air complete with a
mouthpiece that emergency crews might carry.
Not sure if they are for 'fire' use or to revive a patient.
Could they be used for Lloyd's application?

Cheap And Nasty Snorkel extension
 

Glenn Ashmore wrote:

One atmosphere of pressure (14.7 psi) is 33 feet of seawater. THe .445
is correct but your math is wrong. 1.5 atmospheres would be about 50
feet.

One atm is 14.7 psia, it is a measure of absolute pressure. Itis the
pressure at the surface of the water. Pressure at 33 feet depth is 2
atmospheres absolute or 14.7 psig or guage pressure.

To obtain a pressure of 1.5 atmospheres (a measure of absolute pressure)
you would have to descend to around 16 feet. The guage pressure at that
depth is about 7 psig.

The pressure at 7 feet may be described as around 3 psig or 17.7 psia.
It is not by any measure 1.5 atm.

Rick

Cheap And Nasty Snorkel extension
 

Glenn Ashmore wrote:

One atmosphere of pressure (14.7 psi) is 33 feet of seawater. THe .445
is correct but your math is wrong. 1.5 atmospheres would be about 50
feet.

One atm is 14.7 psia, it is a measure of absolute pressure. Itis the
pressure at the surface of the water. Pressure at 33 feet depth is 2
atmospheres absolute or 14.7 psig or guage pressure.

To obtain a pressure of 1.5 atmospheres (a measure of absolute pressure)
you would have to descend to around 16 feet. The guage pressure at that
depth is about 7 psig.

The pressure at 7 feet may be described as around 3 psig or 17.7 psia.
It is not by any measure 1.5 atm.

Rick

Cheap And Nasty Snorkel extension
 

"GA" == Glenn Ashmore writes:

GA It would be extremely dificult if not impossible to breath through a
GA hose at surface pressure if your lungs get more than 2 or 3 feet under
GA water. The difference at 3' is only about 1.5 pounds per square inch
GA but the water is pressing on a couple thousand square inches of lung
GA surface.

The real problem is the "dead volume" in your snorkel. You will be
inhaling your own breath over and over again.

snip

--
Strange attractors stole my wife

Cheap And Nasty Snorkel extension
 

"GA" == Glenn Ashmore writes:

GA It would be extremely dificult if not impossible to breath through a
GA hose at surface pressure if your lungs get more than 2 or 3 feet under
GA water. The difference at 3' is only about 1.5 pounds per square inch
GA but the water is pressing on a couple thousand square inches of lung
GA surface.

The real problem is the "dead volume" in your snorkel. You will be
inhaling your own breath over and over again.

snip

--
Strange attractors stole my wife

Cheap And Nasty Snorkel extension
 

"Lloyd Sumpter" wrote in message
...
Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?


Take a look at the hookah equipment, cheap and cheerful, but recommend you
do a dive training course before use.

http://www.akmining.com/dive/systems.htm

garry

Cheap And Nasty Snorkel extension
 

"Lloyd Sumpter" wrote in message
...
Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?


Take a look at the hookah equipment, cheap and cheerful, but recommend you
do a dive training course before use.

http://www.akmining.com/dive/systems.htm

garry

Cheap And Nasty Snorkel extension
 

We met an interesting and inventive guy on our trip through the Panama Canal
who dealt with this by making his own electric hookah -- take one Jabsco
diaphragm bilge pump, attach hose and a SCUBA mouthpiece and presto, you
have cheap device that will work down a few feet. You want a diaphragm bilge
pump, not a pressure water pump, because the former is relatively high
volume, low pressure.

We used a "real" hookah from Brownie for work on the boat. Vast overkill.

For Fintry, I'm thinking about using a commercial oil-less compressor
(Porter Cable, for example) which will run air tools and, through a filter
(same filters we use on our tank-fill compressor) drive a low pressure hose
for use down to ten feet or so.


--
Jim Woodward
www.mvFintry.com



..
"Lloyd Sumpter" wrote in message
...
Hi,

Whenever I need to work on my prop, etc. underwater, I've just slapped
on the mask and fins and held my breath. But I've always wondered: why not
rig up a hose arrangement to be able to breathe? We're not talking 50-ft
depths here, so I'd think it would be pretty safe. Perhaps some kind of
non-collapsable hose on the end of a snorkel?

Does anyone do this? Why or why not?

Lloyd Sumpter
"Far Cove" Catalina 36