setting to nitrox to reduce over conservatism on dive computers

[Akimbo]

I've seen this term "NDL" several times in this thread. Can someone explain to me how you can dive and have NO deco
Later,
John

Consider it short-hand for No Decompression “stop” Limits.

 

[DaleC]

If you are referring to the notion that every dive is a decompression dive then the corrected statement would be: No (actual vs theoretical) decompression limits. Within the ND limits there has not been enough N saturation to require stops to off gas. In the case of DCIEM tables this was verified by running hundreds of dives and monitoring various time/depth responses. When DCS occurred they rolled back the limit until they had a zero DCS response.

Yes you have some N in your system, but not enough to manifest as DCS. As you approach the limits (on the PADI tables for example) the suggested safety stops become mandatory.

 

[DepthCharge]

Consider it short-hand for No Decompression “stop” Limits.

Thanks,
Was wondering if people really understood what is going on, not ment to insult people.
Later,
John

---------- Post added June 26th, 2014 at 07:31 PM ----------

If you are referring to the notion that every dive is a decompression dive then the corrected statement would be: Yes you have some N in your system, but not enough to manifest as DCS. As you approach the limits (on the PADI tables for example) the suggested safety stops become mandatory.

Ohhhhhhhhh I wouldn't say that. You can get bent on any dive.
Later,
John

 

[MXGratefulDiver]

Ohhhhhhhhh I wouldn't say that. You can get bent on any dive.

Sure you can ... you just have to try harder on some dives than on others.

While we're on the subject of nomenclature, another term I dislike is "undeserved hit". It's misleading ... because if you got bent, it's because you exceeded your body's tolerance for elevated offgassing rates. You may not understand why ... you may have followed all the dictates of whatever computer or table you were using ... but the fact that you got bent means it was deserved.

In all dives we take risks we can never completely eliminate. Best we can do is try to understand what the risks are and decide what's "safe enough". Developing an understanding of why your computer is giving you the data it is giving you is a good start. And watching your ascent rate all the way to the surface is another. Perhaps the most common mistake divers make is to religiously watch their ascent up to the safety stop, wait patiently for three minutes, give each other the thumbs up ... and then surface about five seconds later.

It won't much matter what you set your computer to in that case ... and yet people do it all the time ...

... Bob (Grateful Diver)

 

[jffknapp]

Try to not view newer computers as more conservative. Think of them as more modern with algorithms based off more recent research. Your Suunto may leave you with less NDL on repetitive dives but thats not necessarily a bad thing.

Older dive computer, even dive tables are based off research done in the mid last century. Newer algos from the 80s & 90s and across the board seem to be more conservative. Leads me to believe that the older stuff might have been a little to on the edge for most divers. Especially those older divers, who aren't in college shape and arent up to date on modern safe diving practices or personal skills.




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[Dr. Lecter]

Try to not view newer computers as more conservative. Think of them as more modern with algorithms based off more recent research. Your Suunto may leave you with less NDL on repetitive dives but thats not necessarily a bad thing.

Older dive computer, even dive tables are based off research done in the mid last century. Newer algos from the 80s & 90s and across the board seem to be more conservative. Leads me to believe that the older stuff might have been a little to on the edge for most divers. Especially those older divers, who aren't in college shape and arent up to date on modern safe diving practices or personal skills.




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Ha. Let's not confuse up-to-date research and resulting algorithm implementations generally with Suunto's interesting approach to dive computing specifically.

 

[DaleC]

Ohhhhhhhhh I wouldn't say that. You can get bent on any dive.
Later,
John

Ah, I see... It was a rhetorical question. And I thought you were inquiring in earnest. May I suggest wearing a PFD at all times as you can also drown in a mud puddle.

Do you use V planner for a 10 foot, 10 minute dive or do you accept that the risk does not equal the effort? If the answer is the latter you understand NDL's. These are the limits in which the effort of doing decompression stops does not equal the risk of incurring DCS.

 

[padudle]

I think many of the responders here give dive computers too much credit.

Also, there is a lot of promotional information published about new algorithms and the new computers based on them.

It is not unusual for a diver to test his/her new dive computer next to their old computer, at least for a few dives. The new computers based on the new algorithms generally give less bottom time. Following those new computers will result in lower incidence of DCS.

 

[miketsp]

I've come across several DMs at high intensity dive locations who do some fine tuning of their DCs by upping the % while diving air.
But this is something quite different from the average diver. These guys are diving known and proven site profiles, 5 or 6 times per day every day for years. They know what is safe and what isn't and they're calibrating their DC against established practice to let them know if they've deviated.
This also brings in the factor of conditioning like when the old navy tables were based purely on fit young divers, these guys are also off the curve of the typical rec diver.
So is it safe for them, probably. Would I do it, heck no.

 

[rhwestfall]

Look at the changes dive practices have gone through. Remember 60/60, 100/25? How about 60'/min ascent?

Point is, we think we know more now, and those changes are for better handling the masses.

I find it funny that there are complaints about computers "cheating" you dive time. I learned dive planning using tables and square profiles before there were PDC's.... Run a series of dives with that, and see how it goes for you...