I deco the same way all the time.  Today was 100' for 95 mins on 33%..  deco
was

            decom        jess
50                                1
40                                3
30                                5
switch to o2, 20 and 10 foot stops at 20 feet
20                9              5
20              15            10

total deco  24            24

trout
-----Original Message-----
From: Bill Wolk <BillWolk@ea*.ne*>
To: Adri KC Haine <darkangel@en*.co*>; Techdiver
<techdiver@aquanaut.com>
Date: Sunday, April 04, 1999 6:13 PM
Subject: Re: Deep deco question


>On4/3/99 7:58 AM, Adri KC Haine wrote:
>
>>Basically what you are saying here is that when using helium in your mix
>>(and only then), you can shorten the time of the shallower stops by doing
>>deep stops. This has been proven by the WKPP by still being alive and
>>unbent, right?
>
>Adri -
>
>That's my understanding, but I defer to Jess Armantrout's post for the
>particulars (Trout - thanks for the detailed explanation).  Realize that
>most of my information comes from the same source via the cocoanut
>telegraph -- my trimix instructor was Errol Kalayci, a WKPP member, and
>he telephoned George Irvine during the class for the "revised" deco
>theory.  Now that I've been diving it for about a year, I'm trying to
>figure out from a physiological/ theoretical perspective *why* it works
>-- partly because I enjoy the challenge and partly because I don't enjoy
>being a test subject!
>
>While we're talking specifically about the effect of deep stops while
>diving trimix (at least as far as shortening the time of the shallower
>shops is concerned), Erik Baker's article on deep stops makes a
>convincing case that adding deep stops will reduce the likelihood of DCS
>on any decompression dive regardless of the gasses used.  This is true
>for two reasons: 1) deep stops force you to slow your ascent rate; and 2)
>at the start of deco, the pressure differential between compartment
>pressures and ambient pressure will be lower. (straight Buhlman model
>stops start too shallow.)
>
>>While, OTOH, every Buhlmann based software ( I use zplan a lot) doesn't
>>take that into account and adds time to the shallow stops when doing deep
>>stops , by taking the unproven and probably wrong Buhlmann figures for
>>Helium  on- and offgassing. Am I correct in assuming this?
>
>That's my understanding.
>
>>So, is there any chance some software is incorporating  some "real"
>>compartimental  "a" and "b" values for Helium?
>
>At this point, your *guess* is literally as good as mine. Probably not
>any time soon because they're not known. I don't know if anyone is doing
>the kind of empirical research needed to refine the "a" and "b" values
>for helium.  Comex and Bill Hamilton probably have better ideas, but
>they're not common knowledge, and I don't even think the U.S. Navy is
>doing this kind of trimix research right now.
>
>>Or should we depart from Buhlmanian thinking altogether and incorporate
>>other, more complex algorithms? VPM, bubble stuff ,gradient factors, etc..
>
>Who knows? Buhlman's work has proved itself to be reliable for the most
>part and (except for the helium algorithm) was well tested.  All the rest
>is educated guesswork that may model decompression better in some ways
>and less well in others. What amazes me about mix diving (and deco diving
>in general) is that we're really flying by the seat of our pants.
>Basically, what works is what works.  To me, that's a very sobering
>thought.
>
>
>
>Best regards --
>
>Bill
>
>--
>Send mail for the `techdiver' mailing list to `techdiver@aquanaut.com'.
>Send subscribe/unsubscribe requests to `techdiver-request@aquanaut.com'.

--
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]