Beyond 130 feet: always a deco dive?

[Blackwood]

For me it is. It's not worth gearing up for a few minutes of bottom time.

 

[TSandM]

To do dives below 130 feet, you take some kind of technical training. What the actual classes are called depends on the agency, but it might be Advanced Nitrox/Decompression, or Tech 1, or Tech 45/45, or something else. These classes hone your in-water skills, teach you to handle problems underwater (because you can't surface with a deco obligation) and teach you to do dive planning and gas planning for technical dives. Your equipment changes, because you really should have redundant systems if you're going to go deep enough that you can't surface if something fails, and your gas requirements are so much higher, both for you and for your buddy, if something happens to his. It's many levels of complexity beyond simple, single-tank diving, and the costs and the risks are much higher.

 

[DiveNav]

1. A: At what depth does breathing 100% O2 become deadly?....

It depends ...... How long do you stay at that depth?

 

[DevonDiver]

...and how's your respiration rate?
...and what did you eat last night?
...and what color is your dog?

We have 'safe limits' for O2Tox, based on PPO2. Just limits... where you are statistically not likely to die. Go to a higher PPO2 and you become more statistically likely to die. And so forth... There's a bunch of variables, including time and CO2 retention...and (hypothetically) certain medications etc...

Roll the dice to determine where you stand in the statistics sweep-stake on any given day.

 

[scubadada]

I occasionally venture a little past 130 feet on air. Though my NDLs are short, 9 minutes at 140 feet, 8 minutes at 150 feet (Oceanic DSAT), a multilevel dive generally ends up being of average duration. I take all my dives seriously and plan them ahead of time.

Good diving, Craig

 

[captain]

130 feet is not some magic number. It was the depth the Navy considered the deepest depth at which scuba divers would have enough time both air supply wise and decompression time wise to do a useful amount of work. It has nothing to do with PO2 or nitrogen narcosis or decompression. The early training agencies simply adopted it as part of their training courses without any explaination how it came about.

 

[DivemasterDennis]

Posts like this one bother me, because they imply a diver or divers are trying to learn what they can get away with. So a truthful response, which is that you can do a no decompression dive to deeper than 130 feet ( but not much deeper and not for very long without HUGE risk factors), becomes "mind poison." The list of risk factors and things to know listed in this thread before doing such a dive as a planned dive only scratch the surface of what a diver should know and plan for deep diving with appropriate training, equipment, and support. So if we read the original post to say, hey, can I dive deeper than 130 feet without training for, preparing for and being equipped for a deep decompression dive? the answer is NO!! And the way I put the question and answer is the way I think it should be put and answered.
DivemasterDennis

 

[Tigerman]

...and how's your respiration rate?
...and what did you eat last night?
...and what color is your dog?

We have 'safe limits' for O2Tox, based on PPO2. Just limits... where you are statistically not likely to die. Go to a higher PPO2 and you become more statistically likely to die. And so forth... There's a bunch of variables, including time and CO2 retention...and (hypothetically) certain medications etc...

Roll the dice to determine where you stand in the statistics sweep-stake on any given day.

Even the limits change over time and to some extent between agencies. If youve used 1.6/1.8 for 20 years, will you lower it to 1.4/1.6 because the agency youre with change their standards?
(Outside of a training setting that is)

 

[mstachowsky]

But that wasn't the point of my post. I'm sensing that what I'm asking and what has been answered are very different questions. Let me rephrase:

WHY do some divers who are only trained recreationally go deeper than 130 feet? I realize now from the answers that the answer is "because they are being foolish and trying to push their limits".

The question I did NOT ask was: "LAWLZ! I am teh OW certified this weekendz, guyz can I go to 200 ft? Do u thnk I need a wetsuit?"

See the difference?

 

[Tigerman]

But that wasn't the point of my post. I'm sensing that what I'm asking and what has been answered are very different questions. Let me rephrase:

WHY do some divers who are only trained recreationally go deeper than 130 feet? I realize now from the answers that the answer is "because they are being foolish and trying to push their limits".
....

Sounds just about right to me..