Suunto Cobra too conservative

[designbysue]

I am finding that my Suunto computers (both Cobra and Zoop) are way to conservative - I dive 2 dives, about 45 minutes each to about 70 ft on air and by the end of the 2nd dive I am running into low no deco numbers. Both computers are identical in the numbers. I unusually dive nitrox and don't have any problems but I am in Cancun and there is no nitrox available. I have the computers set to nitrox mode but have them on 21%. I know the PO2 settings change this conservatism somehow but I can't find any info. What setting is less conservative 1.4 or 1.6?

Appreciate any help on this one.

Sue

 

[DuboisP]

1.4 or 1.6 are not relative to conservatism, but only with %oxy and depth.
Are you nitrox certified ?

check what are your settings. P0 or more ?

Master Diver ...

 

[designbysue]

Yes - (I said I usually dive with nitrox) - PO2 is currently at 1.4 - but I heard that changing it to 1.6 allows more bottom time before going into no deco - this statement could be totally incorrect, but is the basis of my question.

 

[vladimir]

You need to review your nitrox training, because you have misunderstood some basic and important (life and death, conceivably) concepts. You should only dive air until you do. I suggest you actually retake the course.

The 1.4 and 1.6 settings for max PO2 are not relevant to your diving on air, assuming you restrict yourself to the first ~187' of the water column.

On my Suunto D9 there is a "personal adjustment setting," P0, P1, or P2, that can be used to adjust the conservatism (P0 being the most liberal). If you don't have a user's manual you can get one at Suunto.com.

 

[designbysue]

vladimir - yes this trip I am diving air only (not sure why you said "I hope") Thanks for confirming the PO2 setting not what I am looking for. My Cobra and Zoop have the P0 P1 P2 settings too - I am leaving in a few minutes for a couple dives and will try to read through the info on those settings and see if I can figure that out. Thanks!

Sue

 

[Tortuga68]

I heard that changing it to 1.6 allows more bottom time before going into no deco - this statement could be totally incorrect

Yes it is totally incorrect

Only thing it will change is your MOD

---------- Post added May 19th, 2013 at 01:11 AM ----------

I dive 2 dives, about 45 minutes each to about 70 ft on air and by the end of the 2nd dive I am running into low no deco numbers

Why is that a problem?

 

[DuboisP]

Yes - (I said I usually dive with nitrox) - PO2 is currently at 1.4 - but I heard that changing it to 1.6 allows more bottom time before going into no deco - this statement could be totally incorrect, but is the basis of my question.

you can dive nitrox without have knowledge or certification.
if you're certified, you must know that partial pressure 1.4 to 1.6 limits %oxy or/and depth.
more oxy, less depth, and vice-versa.
of course, if you're diving breathing 1.6 PpO2 instead 1.4, you will able to dive deeper, and you will have more deco time, or a shorter "no deco" time.
but breathing air at 70ft gives a PpO2 of 0.6, lower these limits.
check also surface interval.
Suunto computers dislike short intervals

 

[Tortuga68]

Both computers are identical in the numbers

Same algorithm so yeah. Why do you use two?

---------- Post added May 19th, 2013 at 01:17 AM ----------

if you're diving breathing 1.6 PpO2 instead 1.4, you will able to dive deeper, and you will have more deco time, or a shorter "no deco" time

She is already confused, you're not helping

 

[DuboisP]

she is already confused, you're not helping

:d:d:d

 

[TSandM]

You aren't getting the bottom times you are used to, because you aren't diving the gas you are used to. You may be able to change the conservativism setting on the computer, but you should be aware that, when you do that, what you're telling the computer is that you're willing to accept a higher risk of DCS.

I would highly recommend a review of your Nitrox class materials, because you appear to have some of the concepts pretty mixed up.