Set conservative mode or not?

[DreaminOfSand&Salt]

I am starting to see that there are (considering we are not air hogs?) times when it would be advantageous to be more liberal (a few dives) and times to be more conservative (numerous deeper dives) - I Think my question has been answered - realizing that I should still compare the planning from my computer to the Tables.

We don't know if we are air hogs yet or not - at 15' in the pool we are both staying down around 55 min and finishing with 17 to 1800 PSI - gonna try to use some of the air planning equations tonight to see how the numbers come out at depth.

The vt3 is Pelagic DSAT and when set to the conservative mode it moves NDLs to the next 3000' elevation.
I think it is a fairly aggressive algo.? - the main reason for my question.

Thanks for all the input and keep em coming if you can think of anything else.

I will check the bottom times on plan mode this evening and compare to tables and post here for opinions.

 

[The Chairman]

I would be curious as to what the difference in the numbers would be when your computer is set on conservative vs the most liberal setting.

The difference is substantial. Some PDCs are inherently more conservative than others. Suunto came out of cold Scandinavian waters and is far more conservative than an Oceanic. If both of those are on a dive together, the Suunto will be the controlling PDC. By the second or third dive, the difference could very well be the Oceanic giving you three times the bottom time as the Suunto. Since my HelO2 has a negative conservancy possibility, I set that so that I can dive with other PDCs. Of course, I am diving in the relatively warm waters of the Keys. Were I to venture into colder waters, that would be adjusted accordingly.

It's important to note that tables and PDCs rely on the same algorithms. When you plan using your PDC, you'll get pretty near the same figures as a table, since the PDC assumes a square profile for planning. Unlike tables, PDCs track your actual N2 exposure allowing you to ride the NDL. Because of this, I recommend that every diver using a PDC execute a full five minute safety stop rather than the traditional three. You'll feel better and you'll go a long way to reducing your chances of DCS even further.

 

[flots am]

Now for the question for the Elite T3 - should we as new divers switch the conservative mode on?

The dive computers all use slightly different algorithms to model nitrogen loading and there's no way to know how well or if it happens to match your personal physiology using it's default settings, without trying it.

Do some dives with it set at whatever "normal" is and take note of how you feel after the dives and that evening. Then set it to a "more conservative" setting and see if you feel any better/less tired.

Unless you're really pushing the time/depth limits, any of the settings are likely to be reasonably safe, although making it more conservative will probably leave you feeling better and reduce the risk of DCS.

Regardless of how you set the computer, a slow ascent up to your safety stop, a nice long safety stop and a very slow final ascent to the surface (maybe take a minute for the last 15') will make you feel a whole lot better after the dive than anything you can set on the computer.

flots.

 

[Lorenzoid]

The "extra-conservativeness" settings that most computers provide can be used if you feel you might be pushing ANY of the factors that are commonly believed to predispose one to or otherwise contribute to an increased likelihood of DCS--not just cold (temperature) and repetitive dives--such as dehydration, obesity, age, smoking, injuries, and dives on which you anticipate you might over-exert yourself or dive a sawtooth profile. So if you're a fat old guy who smokes and broke his arm a few months ago and just got off the plane a bit dehydrated a few hours before that first dive, you might consider setting your computer to add extra conservativeness. But if you're a normal, healthy diver, planning to do very normal dives, I believe most people opt to just leave the extra-conservativeness settings turned off (usually the default setting). As others have said, under normal conditions all you generally need to do is employ the normal safety precautions you were taught, such as sticking to the planned depth/time, ascent rate, and safety stop.

 

[NAM001]

I RUN mY PREDATOR AT ITS DEFAULT SETTING OF 30/85. pERHAPS there is info as to what the liberal and conservative settings are for various manufactures models. that way we can commpare apples to apples.

I would be curious as to what the difference in the numbers would be when your computer is set on conservative vs the most liberal setting. I'm assuming your computer allows you to plan your dive. If you care to do it, why not check how much bottom time your computer allows at both setting say at a max of 60ft. vs 80ft. vs 100ft. and report back. I'm just wondering how much of a difference it would be. And before people go ASC, I'm not telling you to go to 100ft. Just curious about the numbers.

 

[DreaminOfSand&Salt]

I ran the 60,80, & 100 depths with on and off - compared to table:

PDC conservative on 43min 25min 15min
PDC conservative off 57min 30min 19min
Table 50min 30min 20min

Thanks again for all the advice
Brian

 

[diverrex]

The purpose of a computer is to give you a reasonable running approximation of where the edge of the cliff is. Deliberately setting the computer to be more aggressive or less aggressive other than on the sort of grounds that NetDoc indicated is just feeding yourself bad data. If you want to be conservative - be conservative and stay well within what your computer tells you.

Setting your computer to be more conservative and saying "well, I'll just stay inside that" has a small problem and a big problem. The small problem is that it encourages atrophy of the brain. The big problem is that if you break your NDL on an uber conservative setting, you likely have no real sense of where you are in terms of a particular well-known creek (or if in fact you are really in that creek at all...).

(In my opinion. YMMV.)

I agree with that logic. Keep it in the normal mode and then you use whatever conservatism you want in how you deal with the info, for example never go below 5 minutes left in NDL time or whatever makes you feel good about doing.

If your computer was set to conservative and it went into deco and you missed your deco stop did you really miss a stop or were you somewhere in between the normal NDL limits and the conservative deco limits?

 

[BDSC]

Looking at those numbers, I would definitely turn the conservative mode OFF!

 

[fnfalman]

As a long time Elite T3 owner, let me clarify something about this "conservative mode". It isn't like some of the computers with two separate algorithms with the Haldanean/DSAT algorithm being the liberal and then switch to RGBM or Buhlmann for more conservative algorithm.

You turn on this "conservative mode" in the Elite T3 by purposely selecting a higher altitude. That means that you'll be diving at sea level bu the computer is running it as though you're diving at 2000-ft or 4000-ft altitude depending on which level you set it on.

I'd say leave the computer as is and stay well away from the no decompression limit time instead of until the last minute.

 

[Hatul]

You really need to compare the NDL with other computers rather than tables. The Aeris uses the DSAT algorithm which is considered one of the more liberal ones.

Another approach rather than setting personal conservative, is to always surface with the nitrogen loading graph in the green zone.