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This is a multi-part message in MIME format. ------=_NextPart_000_0024_01C0145F.36687D40 Content-Type: text/plain; charset="US-ASCII" Content-Transfer-Encoding: 7bit Guy, Actually there is some strong conviction that these breaks may actually help us off gas more efficiently. Essentially, giving your lungs a break from the high Po2 may be the better way. What a lot of people do not seem to understand is that a deco program is just that, a program that produces a bunch of numbers. What actually goes on when you look at a physiological level is not understood enough at this point and hard to examine. It is certainly not the case that the deco program reflects what is really happening, we know that. What we also know is that it works for now and that is good enough until we find better methods. So if you start discussing these issues with a group of divers that has thousands of hours experience using different gasses and deco, you have to understand that your deco program might not be strong enough a conviction for this group to support your arguments. Theories are one thing, experience the other. Best regards, THOMAS -----Original Message----- From: guy@fi*.vi*.ne* [mailto:guy@fi*.vi*.ne*]On Behalf Of Guy Morin Sent: Thursday, August 31, 2000 1:25 PM To: Techdiver Subject: 80/20 deco 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 ------=_NextPart_000_0024_01C0145F.36687D40 Content-Type: text/html; charset="US-ASCII" Content-Transfer-Encoding: quoted-printable <!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML><HEAD> <META http-equiv=3DContent-Type content=3D"text/html; = charset=3Dus-ascii"> <META content=3D"MSHTML 5.50.4207.2601" name=3DGENERATOR></HEAD> <BODY> <DIV> <DIV><SPAN class=3D182032401-02092000><FONT face=3DArial color=3D#0000ff = size=3D2>Guy,</FONT></SPAN></DIV> <DIV><SPAN class=3D182032401-02092000><FONT face=3DArial color=3D#0000ff = size=3D2></FONT></SPAN> </DIV> <DIV><SPAN class=3D182032401-02092000><FONT face=3DArial color=3D#0000ff = size=3D2>Actually there is some strong conviction that these breaks may = actually=20 help us off gas more efficiently.</FONT></SPAN></DIV> <DIV><FONT face=3DArial><FONT size=3D2><FONT color=3D#0000ff><SPAN=20 class=3D182032401-02092000>Essentially, giving your lungs a break from = the high=20 Po2 may be the better way.</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN = class=3D182032401-02092000>What a=20 lot of people do not seem to understand is that a deco program is just = that, a=20 program that produces a bunch of numbers. What actually goes on when you = look at=20 a physiological level is not understood enough at this point = and <SPAN=20 class=3D992085301-02092000>h</SPAN>ard to examine. It is certainly not = the case=20 that the deco program reflects what is really happening, we know = that. What=20 we also know is that it works for now and that is good enough until = we find=20 better methods. </SPAN></FONT></DIV> <DIV><FONT face=3DArial><FONT size=3D2><FONT color=3D#0000ff><SPAN=20 class=3D182032401-02092000>So if you start discussing these issues with = a group of=20 divers that has thousands of hours experience using different = gasses=20 and deco, you have to understand that your deco program might not = be strong=20 enough a conviction for this group to support your=20 arguments.</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=3DArial><FONT size=3D2><FONT color=3D#0000ff><SPAN=20 class=3D182032401-02092000>Theories are one thing, experience the=20 other.</SPAN></FONT></FONT></FONT></DIV> <DIV><FONT face=3DArial><FONT size=3D2><FONT color=3D#0000ff><SPAN=20 class=3D182032401-02092000></SPAN></FONT></FONT></FONT> </DI V> <DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN = class=3D182032401-02092000><SPAN=20 class=3D992085301-02092000>Best regards,</SPAN></SPAN></FONT></DIV> <DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN = class=3D182032401-02092000><SPAN=20 class=3D992085301-02092000></SPAN></SPAN></FONT> </DIV> <DIV><FONT face=3DArial color=3D#0000ff size=3D2><SPAN = class=3D182032401-02092000><SPAN=20 class=3D992085301-02092000>THOMAS</SPAN></SPAN></FONT></DIV> <DIV><FONT face=3DArial><FONT size=3D2><FONT color=3D#0000ff><SPAN=20 class=3D182032401-02092000> </SPAN></FONT></FONT></FONT></DI V></DIV>= <BLOCKQUOTE=20 style=3D"PADDING-LEFT: 5px; MARGIN-LEFT: 5px; BORDER-LEFT: #0000ff 2px = solid"> <DIV class=3DOutlookMessageHeader dir=3Dltr align=3Dleft><FONT = face=3DTahoma=20 size=3D2>-----Original Message-----<BR><B>From:</B> = guy@fi*.vi*.ne*=20 [mailto:guy@fi*.vi*.ne*]<B>On Behalf Of </B>Guy = Morin<BR><B>Sent:</B>=20 Thursday, August 31, 2000 1:25 PM<BR><B>To:</B> = Techdiver<BR><B>Subject:</B>=20 80/20 deco<BR><BR></FONT></DIV>Hi there,=20 <P>After receiving a barrage of e-mails in regard to this = <BR>discussion, I=20 thought it opportune to put in my two <BR>cent's worth.=20 <P>As part of the rules of engagement here, for me to <BR>address any = rebuttal=20 of my thesis, I will only entertain <BR>issues provided the relate to = the=20 essence of the original <BR>post which is the comparison between EAN = 36 and 80=20 <BR>deco versus EAN 50 and O2. Any digression that does <BR>not = involve a=20 comparison of those two profiles will be <BR>ignored.=20 <P>The most important point in regard to the resulting = <BR>tissue=20 tensions is that the EAN 50 and oxygen profile <BR>as calculated by = the deco=20 software does not take into <BR>account the breaks from breathing pure = O2.=20 <P>This means that if I breath pure O2 for 66 to 75% of <BR>the time = spent at=20 the shallow stops, then I did not <BR>off-gas as much as the = decompression=20 software assumes <BR>I did, given that it calculates based on the = fact=20 that I <BR>should have been breathing pure O2 the whole time.=20 <P>Therefore, the argument that the tissue tensions of <BR>the EAN 50 = and O2=20 decompression are better than <BR>EAN 36 and 80 deco are false. We = really=20 don't know <BR>what the tissue levels are for the EAN 50 and O2 deco=20 <BR>because we are really diving something else. <BR> <BR>Bottom = line is=20 that if one accounts for the breaks from <BR>pure O2 breathing, the = in-water=20 time, for a given algorithm <BR>will increase. I hope everyone can = agree on=20 this point. While <BR>we are not breathing O2, we are not off-gassing = as much=20 <BR>as when breathing O2, and we could be on-gassing in <BR>some = compartments.=20 <P>Basically, what I am proposing involves work. The algorithms <BR>we = use=20 would need to be modified to account for the fact <BR>that we take = breaks from=20 pure O2 decompression.=20 <P>Please try to stick to the paradigm that involves comparison <BR>of = the two=20 profiles. That is to say that if some magical algorithm <BR>were used, = it=20 would have to be used the same way for both <BR>profiles, and would = have to=20 account for the oxygen breaks, <BR>rather than ignoring them.=20 <P>If people on this list are unable to acknowledge the fact <BR>that = pure O2=20 decompression requires breaks that are not <BR>presently accounted for = in=20 decompression software, and <BR>that the substantial amount of time = spent on=20 these other <BR>gasses translates to a material difference in residual = tissue=20 <BR>saturation levels, please do not bother to reply, I don't care = <BR>for=20 hand waving explanations.=20 <P>In addition, any theories, or practices you might think clever = <BR>would=20 also apply for the 80/20. Again, what works for one <BR>profile, must = be=20 applied to both. It's easy to say that we're <BR>not going to account = for=20 those breaks from O2, and if that's <BR>the case, then we have = obviously=20 nothing to discuss.=20 <P>In closing, I trust we can keep the discussion a civil one, = <BR>free of the=20 competitive ramblings that often plague such <BR>exchanges, = specifically: "my=20 deco profile is better than yours." <BR>Those not interested in the = analytical=20 exercise proposed herein <BR>may abstain. <PRE>-- Guy</PRE> </BLOCKQUOTE></BODY></HTML> ------=_NextPart_000_0024_01C0145F.36687D40-- -- Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'. Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.
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