Decompression model on Suunto Vyper

[tstiemerling]

Not sure if this the exactly the right forum for this, but anyway...

I was looking at a couple of old profiles from my Vyper the other day, in partcular a deeper dive in which the Vyper went into decompression mode.

The Vyper has a concept of decompression floor and ceiling depths, and when the computer is in deco mode you are meant to ascend to the between these two for optimal decompression.

My profile on the PC shows the Vyper giving me a deco floor of 10ft, when I went into deco mode at below 130 ft.

My question is what is the justification for this very shallow deco floor? Especially as the computer dropped out of deco mode as I continued my dive at reduced depths.

Anyone have any ideas?

 

[Diver0001]

Not sure if this the exactly the right forum for this, but anyway...

I was looking at a couple of old profiles from my Vyper the other day, in partcular a deeper dive in which the Vyper went into decompression mode.

The Vyper has a concept of decompression floor and ceiling depths, and when the computer is in deco mode you are meant to ascend to the between these two for optimal decompression.

My profile on the PC shows the Vyper giving me a deco floor of 10ft, when I went into deco mode at below 130 ft.

My question is what is the justification for this very shallow deco floor? Especially as the computer dropped out of deco mode as I continued my dive at reduced depths.

Anyone have any ideas?

What did the computer say at the time? Can you reproduce the dive on the simulation software?

R..

 

[BRW]

TT,

Suspect you were in a light deco situation controlled
by fast tissues linked to small bubbles on VYPER. Both
fast tissues and small bubbles "washed out" on way up.
This happens often in shallower, light deco situations.

Bruce Wienke
Program Manager Computational Physics
C & C Dive Tam Ldr
NAUI BOD Vice Chairman

 

[tstiemerling]

I am assuming that what my downloaded profile shows IS what the computer told me at the time. Since it was a couple of years ago I do not remember myself. I have not tried a similar profile in planning mode (but I will). Are you suggesting that there may be a difference in the recorded profile and what actually happened?

What did the computer say at the time? Can you reproduce the dive on the simulation software?

R..

 

[tstiemerling]

Thanks for the response Bruce! Assuming this is accurate
(and I am sure it is, since I understand that you consulted for Suunto on their deco models), then I still dont understand why the floor was so shallow. The instructions that come with the Vyper say that when you are in deco mode you should immediately ascend into the deco zone, ie. above the floor and below the ceiling (or at least thats how I undestood them) - of course not violating maximum ascent rates. It would make more sense to me if the floor was much deeper and maybe the ceiling at 10ft in that situation. But then I cant claim to understand the RGBM model in any detail.

TT,

Suspect you were in a light deco situation controlled
by fast tissues linked to small bubbles on VYPER. Both
fast tissues and small bubbles "washed out" on way up.
This happens often in shallower, light deco situations.

Bruce Wienke
Program Manager Computational Physics
C & C Dive Tam Ldr
NAUI BOD Vice Chairman

 

[BRW]

TT,

The newer SUUNTO computers will have full RGBM
deep stops. The older versions use RGBM bubble
mechanics more sparingly -- mainly for reverse profiles,
altitude, closely spaced repets, and high frequency
multiday diving.

MARES and DACOR (rec) computers have fuller versions of
RGBM.

The behavior you cited, however, would occur in all RGBM
computers for shallower, lighter deco scenarios -- simple
bubble-dissolved gas washout on ascent. Depths and times
for this to occur would very with mix and tissue compartment.

Ascending into the ceiling "zone" is exactly what we all do
on meter, table, or software deco?

BW

Thanks for the response Bruce! Assuming this is accurate
(and I am sure it is, since I understand that you consulted for Suunto on their deco models), then I still dont understand why the floor was so shallow. The instructions that come with the Vyper say that when you are in deco mode you should immediately ascend into the deco zone, ie. above the floor and below the ceiling (or at least thats how I undestood them) - of course not violating maximum ascent rates. It would make more sense to me if the floor was much deeper and maybe the ceiling at 10ft in that situation. But then I cant claim to understand the RGBM model in any detail.

 

[Frank O]

The newer SUUNTO computers will have full RGBM deep stops. The older versions use RGBM bubble mechanics more sparingly -- mainly for reverse profiles, altitude, closely spaced repets, and high frequency multiday diving.

Do you recall when Suunto made the change? I've bought several Suunto computers over the past 3-1/2 years, and I'd be curious to figure out which have which implementation.

 

[Diver0001]

I am assuming that what my downloaded profile shows IS what the computer told me at the time. Since it was a couple of years ago I do not remember myself. I have not tried a similar profile in planning mode (but I will). Are you suggesting that there may be a difference in the recorded profile and what actually happened?

What dr. Weinke says make sense. If the older models are all Bulhmann then you would expect the floor and the ceiling to be the same on light deco scenarios......

R..

 

[IndigoBlue]

Suunto has a dive simulator feature, so you should be able to utilize that feature to re-create the original dive, and the ascent, and see what it tells you to do.

My own cut-off for switching off dive computers and onto tables is 100 ft. If I dive deeper than 100 ft, I would be using Dr Weinke's RGBM dive tables, even in the NDL mode. I don't have a problem with trusting a computer in NDL mode, for one or two dives per day down to 100 ft at most, and preferably closer to 50 ft. But certainly not deeper than 100 ft in my opinion. The NACD cavern depth limit for NDL is 100 ft as well.

 

[BRW]

Guys,

Just one last item before I head out. And thanks for
all the questions and comments across all threads and
posts.

The new Suunto RGBM Deep Stop computer is not
on the market, yet. But will be. Estimate 4 months
from my discussions with Suunto and Sten Stockman
at DEMA (October).

Keep diving, and if your rec computer doesn't do
full RGBM deep stops, you can use the NAUI RGBM protocols
on top of your computer -- 1 minute at 1/2 depth, plus
2 minutes in 15 fsw zone for all no-deco dives deeper than
40 fsw. And add this to any deco regimen supplied by your
haldane computer -- works well and has confluence with
full RGBM down to about 150 fsw.

Cheers,

Bruce Wienke
Program Manager Computational Physics
CounterMeasures Dive Team Ldr
NAUI BOD Vice Chairman

Do you recall when Suunto made the change? I've bought several Suunto computers over the past 3-1/2 years, and I'd be curious to figure out which have which implementation.