Alternate Gas Backup Computer

[NothingClever]

While I appreciate all the input from everyone, I believe many of you are over thinking things a bit. Our goal here is to reduce the risk of an "undeserved" DCS hit.

I think your intentions are prudent and noble but your technique doesn’t seem grounded in any vetted recreational / technical training or commercial procedures. If we were diving together, I think I’d proffer that you’re complicating things unnecessarily.

Why not set a rule that you always ascend two or three minutes short of reaching your ABT? Set both computers for the same gas and keep it simple. If things do get complicated underwater, you want to reduce things that require extra thought.

If you WERE to get a hit and go to a chamber, I think you‘d have a hard time convincing a trained medical provider of your method.

You’re a great candidate for an advanced nitrox and decompression procedures course. Not so you can become a technical diver but because you‘re intending to be a smarter diver and take a more detailed approach to mitigating risk. You’d probably enjoy the academic aspect of the course and appreciate that it enlightens you to dive physiology and where the boundaries really are.

 

[elan]

Like many said above just set the computer for more conservatism and proper gas. If you want to come out cleaner extend your safety stop and slow down the accent rate. What I often do after a deeper rec dives (if there it time available) - I do a 5 min deco stop at 20 ft then slow 6min accent to the surface. I frequently get frowned upon by various guys but then I feel fresh after the dive and they want to go take a nap
That helps a lot when I need to take a long drive home. To take it to another extreme if you are trained for that you can take an O2 with you and do your last 20 ft on O2. Some people do that but it might be too much and onlymakes sense when diving deeper repetitively. But then you are getting into a technical domain.

 

[scubadada]

I think it has been mentioned, if you end up with a Shearwater, you can use SurfGF to end your dive with whatever value you choose for your safety.

There have been numerous examples posted on SB, illustrating how your GF increases significantly during final ascent.

 

[arew+4]

Not to beat a dead horse, but here is some recent "old hearsay" from DAN;

 

[Still Kicking]

Since you are intent on the plan....

Going back to your original question: why do you care about the algorithm if the backup computer is only tracking your MOD and O2 exposure?

 

[Wibble]

Not to beat a dead horse, but here is some recent "old hearsay" from DAN;
View attachment 693272View attachment 693273

Is that a paper or is it official policy?

Seems the former as it's rather radical for the latter.


Question: why do you think you're more likely to get a DCS hit than other people? Is there anything to make you suspect you're more susceptible, such as a known PFO (hole in the heart) or have you had a previous hit?

You're talking about shallow recreational diving within the non-decompression limits (NDL). As long as you're well within the limit, you should be absolutely fine, as in there's a very small risk. There is always a risk to diving, just as there's always a risk that you'll crash your car, have a heart attack, have a piano fall on your head. Life's just that time between birth and death.

Everyone above -- and that's a minor miracle in itself! -- have basically said that you should set your computer to the correct gasses and tweak the "conservatism" setting to make it even less risky.

People make these recommendations with hundreds and thousands of dives way way beyond NDLs and haven't suffered by following the accepted practice. There's always a chance of an "undeserved bend", but they're rare and generally (not always) have something triggering it such as a PFO.



For more reading, I suggest the book Deco For Divers by Mark Powell. I make this purely on the basis of more knowledge and understanding helps mitigate fear and doubt (meant in a non-confrontational way).

 

[arew+4]

Since you are intent on the plan....

Going back to your original question: why do you care about the algorithm if the backup computer is only tracking your MOD and O2 exposure?

Say I was to use a Zoop as the Nitrox computer and An oceanic in DSAT as air computer, in Bonaire where one tens to do many shallow dives a day the could the Zoop end up getting violated?

 

[arew+4]

Is that a paper or is it official policy?

Seems the former as it's rather radical for the latter.

An article just published in a special safety issue of Alert Diver, the DAN puplication.

 

[Wibble]

An article just published in a special safety issue of Alert Diver, the DAN puplication.

If that 'article' is someone's personal opinion it has a lot less weight than if it's official DAN policy. Similarly there's some people who's reputation within the diving community precedes them; an article by them will carry far more weight.

What are the references cited by that paper?

 

[arew+4]

Look I'm not trying to convince you or anyone else, this just came in the mail the other day. I figured I would post it as a counterpoint to the overwhelming unanimous consensus of the "Board" that seems to indicate that I'm some sort of heretical idiot, or at best a misguided simpleton.