Uwatec SMART Microbubble setting

The Uwatec documentation only states that you should set it to Level 5
if you have PFO.

Anybody have any guidelines about setting the microbubble level if you
don't have PFO ?

rgds

monty

On 9 Jul 2003 06:40:58 -0700, monty@scubadiving.com (monty) wrote:

>The Uwatec documentation only states that you should set it to Level 5
>if you have PFO.
>
>Anybody have any guidelines about setting the microbubble level if you
>don't have PFO ?

Monty - I set it to L0, and enjoy the same algorithm that is in the Pro Ultra
and its predecessor: Nitrox Pro.

The problem with the Level settings mode, is that once activated, the
'No-stop' time changes meaning.

It is no longer "time remaining until mandatory deco is imposed".
Instead, it refers to "time remaining until [optional] level stops are imposed".

The purpose of 'level stops' is to guide you through an ascent that will
get you out of the water nearly 100% free of doppler-detectable VGE. DAN Europe
and Uwatec conducted over 1000 dives on the model. It eliminates 100% of high
grade Spencer bubbles, almost all medium grade, and low grade bubbles are
dramatically reduced.

This is fine business. But it comes at a cost. Because of the limited display
real-estate, nomenclature and it's re-use, when level stops are active, you
no longer know where the NDL/mandatory deco line is drawn.

Upon reaching the bottom on a first dive to 65 feet on EAN36 for instance:

LO No-Stop time(time to NDL) will be around 90+ minutes.
L5 No-Stop time(time to Level stop) will be around 20 minutes.
You can model this in the on board deco planner.

I can't emphasize this enough: Level stops are NOT Deco Stops.
You can blow off level stops with no bottom time penalties or lock outs,
or for that matter, serious risk of DCS. True Deco stops are just
the reverse in each of those cases.

Running the 65 foot dive out to 60 minutes, and following the
level stop instructions, you will exit as clean as a whistle.

So there's the problem. No stop time runs out. It's not really time
to ascend, it's just time for level stops to start accumulating.
But the cost (on display) is that you don't know where the NDL is.
BTW, they accumulate time at much slower rates than Deco stops.

Is it useless? On a dive profile you have no experience with, yes.
On a dive profile you are comfortable with, it is very instructive.

e.g. We do certain dives every weekend and know that we cannot exceed
NDL with available gas. Turning up to L5, we discovered that our
current ascent process (rates and safety stops) is already L5 compliant.
We experimented with all our favorites in various combinations and found
there was room for improvement on some profile combinations.

One way around this (troublesome) is to run the dive planner with
L0, to get a picture of your true NDL, then run the dive with L3-L5.

Our experience is that for all but the most provocative situations,
slow controlled ascents and 5 minute stop at 20 will erase/satisfy
all the L5 recommendations for the dives we do with the gases we
use. We are very specialized though and enjoy the benefits of 1000's
of dives of other divers that developed and refined our gas choices.
I doubt that our experience would apply to air divers.

We have dived the Uwatec Pro, Pro Nitrox and Pro Ultras for years and
are quite satisfied/confident with the L0 implementation for our use.
We changed to the Smart Pro for all the other features. I considered
the level stops a deal breaker until I confirmed that L0 replicated
the algorithm we want.

If you run dives out to NDL or beyond with Level stops on, read your
manual very carefully. Level stops are displayed concurrently with
deco stop information and the display does indicate when stop time
is mandatory and when it is not, but it is very subtle. In the event
that you need to get out of the water in minimum time (satisfying
mandatory deco stops only) you need to know how to tell the difference.

safe diving,

bullshark

Hi Bullshark
>
> Received your post re the m/bubble setting on a Smart Pro from Monty - he
> sent out the question on my behalf.
>
> Next question.
>
> I have been diving with the level set to 0 -no problems there.
>
> Have recently notice that it doesn't display the "no deco time" at all.
> Is this normal, my old Aladdin Sport used to display the "deco time" all
> the time.
>
> Have reset it this week to L3 to see if the "deco time is reactivated.
> Plan to dive this weekend - weather permitting
>
> Have you noticed the same thing or is mine going faulty?
>
> Regards
>
> Mike Day