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Scuba Forum / UK Scuba / October 2007

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Decompression

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BB - 26 Sep 2007 18:07 GMT
Yo
Long time ago someone told me he had to come up in a hurry becaouse of
running low on air and was given a new tank and sent straight down again to
finish his decompression.
This would have been 30 odd years ago. Would this have ever been the
thinking? Would it be valid in an emergancy?
Cheers BB
Nigel Hewitt - 26 Sep 2007 19:18 GMT
> Long time ago someone told me he had to come up in a hurry becaouse of
> running low on air and was given a new tank and sent straight down
> again to finish his decompression.
> This would have been 30 odd years ago. Would this have ever been the
> thinking? Would it be valid in an emergancy?

It's been done many times. The real worry is that if it bends you and you
get loosing track dizzy or if you faint you're probably going to drown.

Hence don't run out of air. Hence carry reserves or a buddy to scrounge off
or have a signaling system for 'send more gas' and some gas to send.

In UK home waters we'd rather keep you on the surface and get you
chambered but miles from anywhere who knows what would be best?

It's one of those things that's OK as long as it's OK and when it wasn't
OK it's probably fatal. It's not the same as the old naval trick of surface
them a bit fast and then chamber them for the deco as in a chamber
you can have a funny turn or bring up your lunch and it's not life threatening.

nigelH
BB - 26 Sep 2007 20:37 GMT
Thanks for that.
Just that during a lunchtime talk I was told this was a load of rubbish. I
don't mean this the wrong way and may be my preconceved ideas but think the
person who dis'd it was PADI (as I am so no insult intended). My friend from
years ago was BSAC. The training was far more testing and the equipment less
reliable. Also think less chance of getting to a chamber then.
Cheers me dears.

>> Long time ago someone told me he had to come up in a hurry becaouse of
>> running low on air and was given a new tank and sent straight down
[quoted text clipped - 20 lines]
>
> nigelH
jazzie129uk@yahoo.com - 26 Sep 2007 21:22 GMT
> Thanks for that.
> Just that during a lunchtime talk I was told this was a load of rubbish. I
[quoted text clipped - 30 lines]
>
> - Show quoted text -

It used to be part of the US Navy diving manual, but even that
discusses it as a matter of absolutely last resort. It would never be
used in UK diving. As Nigel says there are too many uncontrollable
variables and effort is concentrated on getting someone to a chamber
as soon as possible.

Danny
ajtessier - 27 Sep 2007 00:08 GMT
I can remember them doing that in a 1950's  (I think) TV show called "Sea
Hunt" that I watched here in the "States" when I was a kid.
Watching that show instilled an interest in diving that I never lost but I
didn't start diving until 1999 when I was 52.

Al
Bottoms Up Divers

>> Thanks for that.
>> Just that during a lunchtime talk I was told this was a load of rubbish.
[quoted text clipped - 44 lines]
>
> Danny
Richard - 27 Sep 2007 01:56 GMT
> I can remember them doing that in a 1950's  (I think) TV show called
> "Sea Hunt" that I watched here in the "States" when I was a kid.
[quoted text clipped - 3 lines]
> Al
> Bottoms Up Divers

Same here in the UK. I watched Lloyd Bridges adventures too & didn't
start diving until 2002 at 52 also.
Lee Bell - 27 Sep 2007 02:06 GMT
>> I can remember them doing that in a 1950's  (I think) TV show called
>> "Sea Hunt" that I watched here in the "States" when I was a kid.
>> Watching that show instilled an interest in diving that I never lost but
>> I didn't start diving until 1999 when I was 52.

> Same here in the UK. I watched Lloyd Bridges adventures too & didn't
> start diving until 2002 at 52 also.

Youngster.
Seadeuce - 27 Sep 2007 22:48 GMT
A very good article on IWR (In Water Recompression) is the following:

http://www.bishopmuseum.org/research/treks/palautz97/iwr.html

....  should answer most queries on the subject, taboo as it is, but
kinda accepted in Australia.

BTW I'm from Ireland - where we practise IPR (In Pub Recompression)

Seadeuce
Rick Hughes - 12 Oct 2007 13:51 GMT
>> I can remember them doing that in a 1950's  (I think) TV show called
>> "Sea Hunt" that I watched here in the "States" when I was a kid.
[quoted text clipped - 6 lines]
> Same here in the UK. I watched Lloyd Bridges adventures too & didn't
> start diving until 2002 at 52 also.

I started diving in 1974  when everyone made their own wetsuits out of kits
from Exchange & Mart, face masks were made of rubber, and the regs I learnt
with were a Siebe Gorman twin hose and Aqua Lung Mistral.

Stopped diving after a few years and took it up again when my son was old
enough to start diving .... wow hadn't the kit changed in 25 years .... (
can breathe from a reg now without a mouthful of water.)
BCD with power inflate .... all big steps forward.

Still have my old lead weight casting mould ... only 4Lb wgt though not 2Kg,
that was the only bit of kit left over from 70's that could still be used.

So at age 50 now back diving on a regular basis .... no longer BSAC, this
time went PADI route with my son, but it's all diving.
Lee Bell - 27 Sep 2007 02:06 GMT
> I can remember them doing that in a 1950's  (I think) TV show called "Sea
> Hunt" that I watched here in the "States" when I was a kid.
> Watching that show instilled an interest in diving that I never lost but I
> didn't start diving until 1999 when I was 52.

You got the name of the show right. Lloyd Bridges played Mike Nelson.

You and I are very nearly the same age, but I got a bit of a head start on
you in diving. I started in 1962, when I was 14.

Lee
JRE - 27 Sep 2007 02:04 GMT
<snip>

> It used to be part of the US Navy diving manual, but even that
> discusses it as a matter of absolutely last resort. It would never be
[quoted text clipped - 3 lines]
>
> Danny

The missed deco procedure is in Chapter 21 of the US Navy Diving manual.
 It details different procedures based on the depth of the deepest
missed stop and how long the diver has been at the surface in Table
21-3.  The table won't post well in plain text without more work than
I'm willing to do tonight, but you can find the entire manual here:

 http://www.coralspringsscuba.com/miscellaneous/usn_manual.htm

The same chapter includes emergency in-water recompression procedures.
They're not for the faint of heart and obviously (to me, anyway) for use
only in dire circumstances.

TDI uses a similar (perhaps identical) missed-stop procedure in its Deco
Procedures class but I'm too lazy to get the book off the bookshelf and
look it up.

The paragraphs introducing the table in the USN DM follow:

21-3 Certain emergencies, such as uncontrolled ascents, an exhausted air
supply, or bodily injury, may interrupt or prevent required
decompression. If the diver shows symptoms of decompression sickness or
arterial gas embolism, immediate treatment using the appropriate oxygen
or air recompression treatment table is essential. Even if the diver
shows no symptoms, omitted decompression must be addressed in some
manner to avert later difficulty. Table 21-3 summarizes management of
asymptomatic Omitted Decompression.

21-3.1 Planned and Unplanned Omitted Decompression. Omitted
decompression may or may not be planned. Planned omitted decompression
results when a condition develops at depth that will require the diver
to surface before completing all of the decompression stops and when
there is time to consider all available options, ready the recompression
chamber, and alert all personnel as to the planned evolution.  Equipment
malfunctions, diver injury, or sudden severe storms are examples of
these situations. In unplanned omitted decompression, the diver suddenly
appears at the surface without warning or misses decompression for some
unforeseen reason. In either instance, the Surface Decompression Tables
may be used to remove the diver from the water, if the surfacing time
occurs such that water stops are either not required or have already
been completed. When the conditions that permit using the Surface
Decompression Tables are not fulfilled, the diver’s decompression will
be compromised. Special care shall be taken to detect signs of
decompression sickness. The diver must be returned to pressure as soon
as possible.

[Table and its notes omitted]

21-3.2 Treating Omitted Decompression with Symptoms. If the diver
develops symptoms of decompression sickness during the surface interval,
treat in accordance with the procedures in paragraph 21-4 (no chamber
available) or paragraph 21-5 (chamber available). If the diver has no
symptoms of decompression sickness or arterial gas embolism, make up the
omitted decompression as described in this section.

21-3.3 Treating Omitted Decompression in Specific Operational
Environments. Refer to paragraph 17-10.6 for procedures for dealing with
omitted decompression during MK 16 diving operations. Refer to paragraph
14-4.10 for procedures for dealing with omitted decompression during
surface-supplied helium-oxygen diving operations.

21-3.4 Ascent from 20 Feet or Shallower (Shallow Surfacing) with
Decompression Stops Required. If the diver surfaced from 20 feet or
shallower, feels well, and can be returned to stop depth within 1
minute, the diver may complete normal decompression stops. The
decompression stop from which ascent occurred is lengthened by 1 minute.
If the diver cannot be returned to the depth of the stop within 1 minute
and the diver remains asymptomatic, return the diver to the stop from
which the diver ascended. Multiply each decompression stop time missed
by 1.5. Alternatively, if the surface interval is less than 5 minutes,
the diver may be placed in a recompression chamber and treated on a
Treatment Table 5 (or 1A if no oxygen is available). If the surface
interval is greater than 5 minutes, the diver may be placed in a
recompression chamber and treated on Treatment Table 6 (or 2A if no
oxygen is available). The diver should be observed for 1 hour after
surfacing and/or completing treatment.

Signature

John Eells

Lee Bell - 27 Sep 2007 02:01 GMT
> Yo
> Long time ago someone told me he had to come up in a hurry becaouse of
[quoted text clipped - 3 lines]
> thinking? Would it be valid in an emergancy?
> Cheers BB

Yo

Yes and yes. Do some research on "in water recompression."

Lee
Adam Helberg - 02 Oct 2007 07:24 GMT
> Yo
> Long time ago someone told me he had to come up in a hurry becaouse of running low
[quoted text clipped - 3 lines]
> Would it be valid in an emergancy?
> Cheers BB

There was a fatal accident a few years ago from something like this in San Diego. If
remember correctly she was handed a scuba unit and it slipped out, she sank and was
unsuccessful at dumping her weights. There was some problem like this with regaining
buoyancy and she drowned.

I don't know if it's recommended but if done someone needs to go down and stay with
the diver in case of problems. You should not just give the diver a new tank and hope
everything will be fine.

Adam
Adam Helberg - 02 Oct 2007 09:28 GMT
>> Yo
>> Long time ago someone told me he had to come up in a hurry becaouse of running low
[quoted text clipped - 14 lines]
>
> Adam

Here's a link to the details of the accident:
http://www.southcoastdivers.com/cgi-southcoastdivers/dincdis.pl?dinc=20010107.txt
David Owens - 20 Oct 2007 12:06 GMT
>Long time ago someone told me he had to come up in a hurry becaouse of
>running low on air and was given a new tank and sent straight down again to
>finish his decompression.
>This would have been 30 odd years ago. Would this have ever been the
>thinking? Would it be valid in an emergancy?

The physics is perfectly valid - but as other posters have commented
it would be far from the recommended approach.  It may accasionaly be
the best option but only if the alternatives were equally unappealing.
diowens@bluebottle.com
 
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