Caution to everyone using hoseless computers!

[Boogie711]

"Twice as many breaths is does NOT mean twice as much nitrogen absorbed into your tissues."

Thank you Charlie, which is what I meant earlier.

I am aware of the effects of work-rate and temperature and the risk profile for DCS. I know breathing higher percentages of O2 (say on deco stops) helps promote off-gassing.

The insinuation that "If the integrated computer records pressure as low and calculates your air consumption as low as a result you could be diving beyond your tables and be a risk of DCS" is simply wrong, for a number of reasons.

A) Just about any computer will let you dive "beyond your tables." Because they calculate multi-level dives.

B) As stated, no computer is going to EXTEND NDL based on any factor, much less air consumption. (Unless you were diving air on a Nitrox setting or something stupid - I can see how a stupid person might get confused there.)

C) As also stated, air hogs don't incur a higher nitrogen load than air-sippers.

Yet another reason for Uncle Pug to come here and issue a hearty "Computers Rot Your Brain" edict. And on this one, I have to wholeheartedly agree.

 

[ba_hiker]

Another point here. Why would you dive with a wireless computer and not have a SPG? I mean if you have any problems with the thing you don't know how much gas you have.

I dive a suunto vytec and have bottom timer and a SPG too. I cross check the SPG, depth guage, and the vytec perodically through the dive. I check the no deco limits at the expeted bottom before the dive, and if the computer fails (it actually hasen't) i dive to the limit and return with a safety stop.

i work too much with computers to just trust them.

 

[Jai Bar]

To some extent, higher breathing rate results in higher nitrogen absorption. During a single breath we inhale gas with a PPN2 of "X" bars (0.8xdepth_pressure). In the lung's alveoli there is blood with lower PPN2, thus N2 flows from lungs to blood vessels (from here it will go to all tissues and get absorbed in a similar way).
The N2 flow (and any other gas) is from high partial pressure to low. The N2 flow is an exponential behavior, so if we hold our breath the partial pressure difference between lungs and blood decreases --> flowing of N2 from lungs to blood decreases with time. If we breath rapidly, there is a constant supply of N2 with high partial pressure, so we keep a higher partial pressure difference between lungs and blood --> more N2 absorption. My guess is that the difference between holding long breaths or keeping a high breathing rate is negligible (it can be calculated... ).

However, N2 is the lesser problem while breathing- there are other gases that are of more concern: the most important is to get rid of excessive CO2 (which builds up quite fast and is of more immediate concern than other gases we breath!) and also get fresh O2, so better keep a normal breathing rate