Two more rebreather patches

Dirk Hohndel dirk at
Mon Oct 27 09:10:11 PDT 2014

On Mon, Oct 27, 2014 at 11:29:47AM -0400, William Perry wrote:
> >> 
> >> I just finished  by CCR training down in Bonaire last week so I don’t have a
> >> lot of experience, but I did find that minor depth changes did not impact
> >> the loop volume enough for me to feel the need to add diluent.  My inhale
> >> was cut very slightly short (I was diving with the auto-diluent-valve off
> >> after the initial big descent).  This would be equivalent to the occasional
> >> mask clear at depth.  If you are doing a ton of 10 meter ascents/descents in
> >> a cave system as it winds around then those will add up quickly, but 1-2
> >> footers is noise.
> > 
> > I agree: 1/2 foot is noise, 10 m is significant.
> > 
> > What value do you think we should use as limit? I just proposed 1 m on
> > my previous email to Robert but I'm not sure if this value is big
> > enough.
> > 
> > What do you think?
> Maybe start tracking it if they stay at the new depth for more than a
> certain # of samples?  If I just drop down quickly to look at something
> I’m not going to mind a short breath or two but if I am following the
> contour of the reef and stay at that depth for 5-10 minutes I will
> probably squirt in some diluent.  I’m generally not a fan of heuristics
> like that though.

With the benefit of absolutely know subject matter expertize, I think what
would make sense is to smooth out the depth graph. Something like a
gliding average across one minute - that should remove jitter and the
quick pop down to look at things that you describe, at the same time it
should be reasonably close to what I would call the "perceived depth"
during a dive - and I think that's what people will tend to base their
change to the counter lung content on...

Again, just running my mouth (errr, fingers) and making things up here :-)


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