Average Depth Diving?

[Thalassamania]

I honestly dont mean to insult anyone, but sadly the internet is an imperfect means of communication so maybe it can seem that way.

Too true, too true. But it's been fun ... I managed to get the flame police on my butt for the first time. Touchy, touchy are they ... God forbid if I ever really tried to be nasty<G>.

 

[DivesWithTurtles]

... You can make things as complex as you want on land because you have plenty of time and resources to figure out complex problems (and you aren't narcd

But in water you need something simple, reliable and flexible. ...

(I know this doesn't really add anything of substance to this discussion, but...) Sounds kinda like a dive computer to me.

 

[DivesWithTurtles]

Because there is (as far as I know and I am not an expert -- as we all know) research that shows that even if you ascend slowly enough not to exceed an M-value, you can still generate bubbles which can then be hard to get rid of.

The DIR model combines an ascent profile that tries to reduce the generation of these bubbles in the initial part of the ascent before reverting back to a more conventional profile for the shallower depths.

(Clearly, I'm much less of an expert than you.)

I agree with your first paragraph completely.

A few DIR-F students here have mentioned having been taught a 30 second travel - 30 second stop (very slow) linear ascent profile on rec no-deco dives. That is a different "DIR model" than the "DIR model" that you are referring to here, yes?

Has/have the DIR model(s) ascent profile that tries to reduce the generation of these bubbles in the initial part of the ascent been subject to any research to see if it indeed accomplishes that goal?

 

[MXGratefulDiver]

How many of you involved in this discussion think that your computer really can keep you safe? Does it know anything about your physiology? Your eating/drinking/sleeping habits? Your age and/or physical conditioning?

Use one if you need it ... don't if you don't. "Safe" is more about understanding why you're diving the profile you choose to dive ... and in your ability to carry it out according to plan.

I've known several people ... one very experienced diver, recently ... who got bent even though according to their computer they did everything right. We all take our chances ... and through experience, we learn how to do what works well for us to minimize the risks.

That's about all you can ever expect to accomplish ...

... Bob (Grateful Diver)

 

[limeyx]

(Clearly, I'm much less of an expert than you.)

I agree with your first paragraph completely.

A few DIR-F students here have mentioned having been taught a 30 second travel - 30 second stop (very slow) linear ascent profile on rec no-deco dives. That is a different "DIR model" than the "DIR model" that you are referring to here, yes?

Has/have the DIR model(s) ascent profile that tries to reduce the generation of these bubbles in the initial part of the ascent been subject to any research to see if it indeed accomplishes that goal?

The ascent profile is essentially the same. I usually do (for rec dives)
1 min stop at a depth. Since I dont have a "seconds counter" on my watch, I move at each minute interval and count the travel time to the next stop as stop time, so it works out about the same.

The WKPP divers have subjected themselves to doppler tests on some of their big dives. I believe other people have done so on 2-300 feet or so dives.

The DIR ascent model is also (loosely) based on output from deco planners in various forms.

A number of people on our very own scubaboard have reported feeling much better when diving if they introduce a "deep stop" in their profile oh, say at about 1/2 the max depth of their dive. Which is oddly where DIR divers (rec dives) start their stops.

One difference is that in DIR, once you start stopping (pardon my English), then stops come every 10 feet, whereas other deep stop models then have the diver ascend more quickly after the deep stops.

I'm honestly not sure how you would measure bubble growth in water except to do a bunch of dives and see how the end results vary (doppler and fatigue). Interesting to note that other agencies are now promoting deep stops!

 

[limeyx]

How many of you involved in this discussion think that your computer really can keep you safe? Does it know anything about your physiology? Your eating/drinking/sleeping habits? Your age and/or physical conditioning?

Use one if you need it ... don't if you don't. "Safe" is more about understanding why you're diving the profile you choose to dive ... and in your ability to carry it out according to plan.

I've known several people ... one very experienced diver, recently ... who got bent even though according to their computer they did everything right. We all take our chances ... and through experience, we learn how to do what works well for us to minimize the risks.

That's about all you can ever expect to accomplish ...

... Bob (Grateful Diver)

yes, this especially applies to a dive I did on Monday.
We were diving with a lady who has had a major surgery (a long time ago) and gets skin bends if she follows standard DIR deco ascents.

So we simply padded the deco by an extra 5 mins as that's what she has emperically figured out works for her at those depths/times. She came out of the water fine.

If she were the kind of person to follow a computer, I am not sure she would have had the tools to modify her profiles very well.

 

[limeyx]

(Clearly, I'm much less of an expert than you.)

I agree with your first paragraph completely.

A few DIR-F students here have mentioned having been taught a 30 second travel - 30 second stop (very slow) linear ascent profile on rec no-deco dives. That is a different "DIR model" than the "DIR model" that you are referring to here, yes?

Has/have the DIR model(s) ascent profile that tries to reduce the generation of these bubbles in the initial part of the ascent been subject to any research to see if it indeed accomplishes that goal?

There are some interesting articles here:

http://www.gue.com/Research/Exercise/index.html

Some may be a bit dated, and how much is experimentation compared to "hard fact" is open to interpretation -- but where do you think the original data that computers use comes from? The same kind of experimentations!

 

[Thalassamania]

but where do you think the original data that computers use comes from? The same kind of experimentations!

Actually I know where they came from, since one my housemate was one of the EDGE developers. The problems facing the first computer builders had nothing to do with decompression models, that was all "well known" and accepted. The problems were stable transducers, temperature corrections, battery voltage corrections, temperature induced battery voltage drop, current consumption, not enough memory, code that was too big, efficient display drivers, waterproof packaging, non-volatile memory, etc. There were all these technical problems that needed to be solved, no one was worried about the model, that was set.

 

[limeyx]

Actually I know where they came from, since one my housemate was one of the EDGE developers. The problems facing the first computer builders had nothing to do with decompression models, that was all "well known" and accepted. The problems were stable transducers, temperature corrections, battery voltage corrections, temperature induced battery voltage drop, current consumption, not enough memory, code that was too big, efficient display drivers, waterproof packaging, non-volatile memory, etc. There were all these technical problems that needed to be solved, no one was worried about the model, that was set.

What does that have to do with decompression? My point was that the deco algorithms built into computers are not "magic" they too are best guess based on data collected, experimenation and attempts to model how things really work.

From what people seem to be saying it's as though computers are perfect and can make no mistakes and anyone else that doesn't use the exact same output as a computer or existing deco program is just picking stuff out of the air.

 

[DivesWithTurtles]

There are some interesting articles here:

http://www.gue.com/Research/Exercise/index.html

Some may be a bit dated, and how much is experimentation compared to "hard fact" is open to interpretation -- ...

Thanks for the link. Looks like there may be some interesting articles there. I'll read up.