Mailing List Archive

Mailing List: techdiver

Message Display

Date: Thu, 21 Sep 1995 14:51:56 -1000 (HST)
From: Richard Pyle <deepreef@bi*.bi*.Ha*.Or*>
To: Anthony Martinez <Anthony_Martinez@cc*.ss*.nm*.go*>
Cc: techdiver@terra.net
Subject: Re: Re[4]: DCS and injury sites


> On these dives, what is the origin of your deco schedule? (i.e. Buhlman,
> RGBM, etc.) 

My trimix tables were based on ProPlanner (Neo-Haldanian). My rebreather 
tables are based on DCAP.  In both cases, I just make up the deep stops as I 
go along.

> Also did you make any modifications to what the schedule called
> for in order to account for the deeper stops? The compartment-based models
> would seem to penalize you for making deeper stops on helium.

I tend to be extra conservative on decompression profiles, so I add the 
time of the deep stops to the bottom time, then follow tables accordingly 
(I.e., leave the bottom after 15 mins, do 4 mins of deep stops, follow 
decompression as if I did 20 minutes on the bottom).  But that's just me. 
In reality, the models that calculate schedules based on bubble physics 
tend to incorporate *both* deep stops *and* less total deco time.  I'm 
*not* recommending that anyone try "winging" that procedure, because if I 
did recommend that, I would undoubtedly get sued.

> Your method
> may not produce an appreciable increase in DCS risk, but I'm not sure if
> that would hold true on dives with greater bottom times. Then, at the
> depths we're talking about (>300fsw?), long bottom times are not very
> practical in open ocean anyway. Of course, I'm only thinking about deep
> stops on a helium mix, if you're using a mix without helium, it seems to
> make a lot of sense. - Tony

I think, if you view decompression physiology in terms of minimizing 
bubble growth (we know they're there after almost all deep dives), rather 
than eliminating dissolved gas from theoretical tissue compartments, then 
the deep stops make a lot of sense no matter what the diluent is. 
Incidently, even with compartment-based models, helium dives call for 
deeper initial stops. Another incidently -- I do "deep stops" on ALL of 
my dives - even 40-footers.  It's just that, when I do them on a dive 
that has no "required" decompression stops, they're called "safety 
stops".  Same basic concept.

Aloha,
Rich

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]