Faith diving and magic?

[Ayisha]

What I am saying is that we are playing with fire, when we use a computer. they are great devices, they manage the many data points going on in a dive and give us a readout that is easy to understand and use.

...this is back to faith and magic, faith in a computer is like believing in magic for me. I have faith, and I believe but I still question.

I still think that you're not grasping what pretty much everyone is trying to tell you. This isn't about faith in your computer(s). If you or your wife had ended your dives when your computer indicated you should, you would not have gone into deco in the first place. You CHOSE to go into deco, knowing that your wife's computer was going to be "screaming" more than yours. You showed no faith in your computer and did not create or follow any plan of your own either.

Is this questioning of your dive computer(s) about the fact that you did not noticeably get bent even though you had a deco obligation left? We would never know from day to day if that profile will get us bent or not. It might have worked for you and your wife this time, and maybe even other times, but of course there are umpteen factors that affect your susceptability to DCS on any given day. Also, if anything had gone wrong, you would have had even less gas to complete the deco obligation. If you're going to go into deco, you would be well advised to plan those dives appropriately and with the corresponding training and equipment. The people who have been advising you in that area are known to be highly experienced and trained in that regard.

 

[Charlie99]

Originally Posted by SailNaked
...............
figure this on a table, you did a 130ft dive for 59 minutes, 1.5 hour SI, then you did an 80ft dive for 63min, 2.5h SI 80ft 65min, then a 60ft dive for 58min. (all with 5 min safety stops)

I didn't see any problem with applying tables to those three dives, so I presume the question was how to check on the computer before the first and each subsequent dive.

The first dive by itself is well beyond table limits. Add in the 2nd dive and then a 3rd dive and I don't see how you would apply the table to get any reasonable info.

Square profile tables used in the normal method are not compatible with the highly multilevel dives described by the OP.

I am curious about how you would use tables to get any sort of feel for whether the computer calculations are in the right ballpark.

I have my own methods of using tables, but they are non-standard ways of using tables in a way that generates results identical to the PADI wheel.

 

[lowviz]

The first dive by itself is well beyond table limits. Add in the 2nd dive and then a 3rd dive and I don't see how you would apply the table to get any reasonable info.

Square profile tables used in the normal method are not compatible with the highly multilevel dives described by the OP.

I am curious about how you would use tables to get any sort of feel for whether the computer calculations are in the right ballpark.

I have my own methods of using tables, but they are non-standard ways of using tables in a way that generates results identical to the PADI wheel.

Had no problems applying my tables. Tables tell me the first dive is idiotic with respect to NDL but just doable (gas load) with 28% and accelerated deco. Computer (VR3) tells me the same thing, so I'm guessing that it is still working. What would I do in Coz? Plan a reasonable dive and go with the flow. I'm not a hero, I just love to dive.


I still don't get the issue with computers vs. tables. Just different ways of serving up the same information from the algorithm that you "trust". Tables give you less choices is all I can determine.

..............I am curious about how you would use tables to get any sort of feel for whether the computer calculations are in the right ballpark..................

Put your computer in dive plan mode, it knows what your loading is from previous dives. Compare its suggestions to the table of your choice or something like V-Planner.

 

[SailNaked]

Yall are really funny with this faith in your ability to plan. and your belief that it makes you safe. it is like a catholic and a Jew discussing God.

Real fact, the tables and the computers are all based on empirical evidence that they mostly work. they will not work in every situation and they will not keep every one safe every time. believe in whatever superstition you like until they have a gas monitor attached to your body they are not 100% safe.

You can not dive 130ft for 58 minutes unless you are diving multi levels and the average depth is really something under 60 ft. I dont care what you Expensive toy says or how many deco bottles or nitrox you plan it with, we did it on a single tank of air. and it happens in Coz every day.

fact is we went into deco on a 36ft dive. and did 27 minutes of hang time. how many of you plan for that?

I certainly learned something, you should too.:cool2:

 

[DandyDon]

* we did a total of 21 minutes of deco, total dive time about an hour(58m) max depth about 80ft.

fact is we went into deco on a 36ft dive. and did 27 minutes of hang time. how many of you plan for that?

I missed the change along the way here...??

You went into deco because you ignored your high priced computers.

 

[openmindOW]

Thank you for your post, SailNaked. By posting here, you are helping other divers. Thanks.

I will never do unplanned deco on the fly again,

Lesson learned.

Keep diving.

 

[openmindOW]

Let he who is without sin cast the first stone.

Yes. Thank you.

 

[openmindOW]

In general, dive computers aren't really all that reliable ... because the NDL they're going to display is heavily dependent on the algorithm used to make the calculations. I used to own two dive computers ... a Suunto Vytec and an Oceanic Versa Pro. Once just for giggles I decided to dive them strapped side-by-side on my arm on a fairly aggressive dive to about 110 fsw. At one point in the dive, the Suunto was telling me I was skirting NDL while the Oceanic was telling me I had 26 minutes of NDL time remaining.

Interesting.

The bottom line is this ... your no-decompression limit isn't a number, and it isn't based on your dive computer's algorithm ... it's based on your physiology, and on a number of factors that affect your physiology that change on a daily basis (hydration, sleep, stress levels, exertion, and a host of others).

Amen.

I know an experienced recreational diver who got bent while, he says, he was well within the limits of his DataMax computer. He's okay now and is back to diving.

 

[lamont]

Yall are really funny with this faith in your ability to plan. and your belief that it makes you safe. it is like a catholic and a Jew discussing God.

Real fact, the tables and the computers are all based on empirical evidence that they mostly work. they will not work in every situation and they will not keep every one safe every time. believe in whatever superstition you like until they have a gas monitor attached to your body they are not 100% safe.

If you actually are trained to do decompression, you should have been exposed to that concept already in the course you took.

For the record, you are the one that was most recently blindly following their computer because "that's the way they do it in coz and we can't plan dives there" or some logic like that, and who wound up nearly running OOA on a mandatory deco stop their computer called out.

So, yes, you need to plan your dives, which is something you failed to do (and you apparently still refuse to listen to that advice), but yes, we all operate understanding that the algorithms are largely voodoo. One thing to consider is that if you are doing extremely multi-level diving down to 130 like you've posted that you are effectively 'riding the NDL' curve and you are operating at the very limits of the algorithm (not what they were designed for or the data that went into them -- which was typically square profile) and you should bake some additional conservatism into your profiles.

 

[openmindOW]

You can comment, and instruct those that have made mistakes, without making them feel like a fool, even if what they did was foolish ... you DO want others to post their mistakes so we, and they, can learn from them, don't you?

Amen.