Mailing List Archive

Mailing List: techdiver

Banner Advert

Message Display

Date: Thu, 31 Aug 2000 13:24:30 -0400
From: Guy Morin <xnet@vi*.ca*>
Subject: 80/20 deco
To: Techdiver <techdiver@aquanaut.com>

--Boundary_(ID_6DQWXViDaKMj0X+CYTiCyg)
Content-type: text/plain; charset=us-ascii
Content-transfer-encoding: 7bit

Hi there,

After receiving a barrage of e-mails in regard to this
discussion, I thought it opportune to put in my two
cent's worth.

As part of the rules of engagement here, for me to
address any rebuttal of my thesis, I will only entertain
issues provided the relate to the essence of the original
post which is the comparison between EAN 36 and 80
deco versus EAN 50 and O2. Any digression that does
not involve a comparison of those two profiles will be
ignored.

The most important point  in regard to the resulting
tissue tensions is that the EAN 50 and oxygen profile
as calculated by the deco software does not take into
account the breaks from breathing pure O2.

This means that if I breath pure O2 for 66 to 75% of
the time spent at the shallow stops, then I did not
off-gas as much as the decompression software assumes
I did, given that it calculates based on the fact that I
should have been breathing pure O2 the whole time.

Therefore, the argument that the tissue tensions of
the EAN 50 and O2 decompression are better than
EAN 36 and 80 deco are false. We really don't know
what the tissue levels are for the EAN 50 and O2 deco
because we are really diving something else.

Bottom line is that if one accounts for the breaks from
pure O2 breathing, the in-water time, for a given algorithm
will increase. I hope everyone can agree on this point. While
we are not breathing O2, we are not off-gassing as much
as when breathing O2, and we could be on-gassing in
some compartments.

Basically, what I am proposing involves work. The algorithms
we use would need to be modified to account for the fact
that we take breaks from pure O2 decompression.

Please try to stick to the paradigm that involves comparison
of the two profiles. That is to say that if some magical algorithm
were used, it would have to be used the same way for both
profiles, and would have to account for the oxygen breaks,
rather than ignoring them.

If people on this list are unable to acknowledge the fact
that pure O2 decompression requires breaks that are not
presently accounted for in decompression software, and
that the substantial amount of time spent on these other
gasses translates to a material difference in residual tissue
saturation levels, please do not bother to reply, I don't care
for hand waving explanations.

In addition, any theories, or practices you might think clever
would also apply for the 80/20. Again, what works for one
profile, must be applied to both. It's easy to say that we're
not going to account for those breaks from O2, and if that's
the case, then we have obviously nothing to discuss.

In closing, I trust we can keep the discussion a civil one,
free of the competitive ramblings that often plague such
exchanges, specifically: "my deco profile is better than yours."
Those not interested in the analytical exercise proposed herein
may abstain.

--
Guy



--Boundary_(ID_6DQWXViDaKMj0X+CYTiCyg)
Content-type: text/html; charset=us-ascii
Content-transfer-encoding: 7bit

<!doctype html public "-//w3c//dtd html 4.0 transitional//en">
<html>
Hi there,
<p>After receiving a barrage of e-mails in regard to this
<br>discussion, I thought it opportune to put in my two
<br>cent's worth.
<p>As part of the rules of engagement here, for me to
<br>address any rebuttal of my thesis, I will only entertain
<br>issues provided the relate to the essence of the original
<br>post which is the comparison between EAN 36 and 80
<br>deco versus EAN 50 and O2. Any digression that does
<br>not involve a comparison of those two profiles will be
<br>ignored.
<p>The most important point  in regard to the resulting
<br>tissue tensions is that the EAN 50 and oxygen profile
<br>as calculated by the deco software does not take into
<br>account the breaks from breathing pure O2.
<p>This means that if I breath pure O2 for 66 to 75% of
<br>the time spent at the shallow stops, then I did not
<br>off-gas as much as the decompression software assumes
<br>I did, given that it calculates based on the fact that I
<br>should have been breathing pure O2 the whole time.
<p>Therefore, the argument that the tissue tensions of
<br>the EAN 50 and O2 decompression are better than
<br>EAN 36 and 80 deco are false. We really don't know
<br>what the tissue levels are for the EAN 50 and O2 deco
<br>because we are really diving something else.
<br> 
<br>Bottom line is that if one accounts for the breaks from
<br>pure O2 breathing, the in-water time, for a given algorithm
<br>will increase. I hope everyone can agree on this point. While
<br>we are not breathing O2, we are not off-gassing as much
<br>as when breathing O2, and we could be on-gassing in
<br>some compartments.
<p>Basically, what I am proposing involves work. The algorithms
<br>we use would need to be modified to account for the fact
<br>that we take breaks from pure O2 decompression.
<p>Please try to stick to the paradigm that involves comparison
<br>of the two profiles. That is to say that if some magical algorithm
<br>were used, it would have to be used the same way for both
<br>profiles, and would have to account for the oxygen breaks,
<br>rather than ignoring them.
<p>If people on this list are unable to acknowledge the fact
<br>that pure O2 decompression requires breaks that are not
<br>presently accounted for in decompression software, and
<br>that the substantial amount of time spent on these other
<br>gasses translates to a material difference in residual tissue
<br>saturation levels, please do not bother to reply, I don't care
<br>for hand waving explanations.
<p>In addition, any theories, or practices you might think clever
<br>would also apply for the 80/20. Again, what works for one
<br>profile, must be applied to both. It's easy to say that we're
<br>not going to account for those breaks from O2, and if that's
<br>the case, then we have obviously nothing to discuss.
<p>In closing, I trust we can keep the discussion a civil one,
<br>free of the competitive ramblings that often plague such
<br>exchanges, specifically: "my deco profile is better than yours."
<br>Those not interested in the analytical exercise proposed herein
<br>may abstain.
<pre>-- 
Guy</pre>
 </html>

--Boundary_(ID_6DQWXViDaKMj0X+CYTiCyg)--
--
Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.

Navigate by Author: [Previous] [Next] [Author Search Index]
Navigate by Subject: [Previous] [Next] [Subject Search Index]

[Send Reply] [Send Message with New Topic]

[Search Selection] [Mailing List Home] [Home]