Do Dive computer get you bent more than tables?

[sharpenu]

I don't think that the agencies are to blame. The problem lies with diver inexperience. That is why young drivers cause a disproportionate number of auto accidents. Same in diving or any other activity. The safest thing to do is dive often. More diving=more experience=less accidents.

 

[Lance Gothic]

Brothers & Sisters of the U/W Realm,

Here, here to your collective insight!

Remember that there are variables. For those of us that are endowed with a low % of body fat we may use less rigid tables. All right then, some of us are higher on the 'pleasingly plump' side and it takes those little compressed gases a bit longer to come out of saturation.

You must take personal physical condition into account at all times. Even healthy divers get "bent".

It behooves each of us to make a strong series of controlled immersions and ascents to set our personal limits. A coordinated LDS project, club effort with medical personnel present and PLANNING should be the keystone here.
Prior to the dive we need to discuss our dive plan with our buddy, team +/or group. Plan the dive & Dive the plan!

In aviation there's what's known as "Get-home-itis". This is described as the urgent need to terminate the safe conduct of a flight prior to the safe termination of any flight. Missed go-arounds have caused accidents which could have been avoided through a firm resolve to safely operate the aircraft as opposed to just getting the whole mess down on the ground.

Are you prepared for the onset effects of bends? Do you recognize them? What can be done at the dive site to resolve the issue? Is re-immersion preferential or is there a chamber nearby?

Enjoy the immersion - do not deny the ascent.

Regards,
Lance Gothic
Shibumi

 

[devjr]

"Gethomitus", that's what happened alright, but I think that's about as far as the aviation analogy goes. Dr Deco has convinced me that bends onset hinges on too many variables to allow the weeding out of "susceptibles" through testing, controlled or otherwise. Except, that is, for the odd example of congenital weakness where bubble scanning, PFO diagnosis, and wretched screams of "pain" might be indicative. Interestingly, it's been done before, called "witch ducking" I believe(laughing).

 

[Aquamore]

Whilst performing my duties as a UK Joint Services Military Diving Supervisor (SADS), I have on occasions witnessed what I would call "The Polaris Ascent".

A group of Civilian divers were practicing a CBL (Controlled Bouyant Lift) where the rescuer inflates his Buddies Vest/Bouyancy device to bring him to the surface in a controlled manner at the correct rate.

Possibly due to the age and/or inexperience of the divers they would frequently break the surface at an alarming rate. (You get suspicious that they have come up to fast when their bodies are fully visible down to the knees.

This is where the 'Aviation Analogy' comes into play again..... these guys should be wearing Altometers and not depth guages.

I believe that anyone who has problems ascending in the correct manner should practice coming up on a 56 pound weighted Shot line so that if they do start ascending out of control (despite all the training in the pool they should have had), they can at least grab hold of the Shot-line to stop their ascent.

As I said earlier, tables and computers don't bend divers - unsafe diving practices do!

Aquamore
Dive Safely (Ascent or Descent)

 

[Dr Deco]

Dear Readers:

One must always remember that the major determinant of DCS is gas loading. No matter how many ladders you climb or how many scuba tanks you lift, you cannot get the bends if you are not over saturated.

Next in line comes some individual variability that has yet to be determined. This has been known for decades but the reason(s) are difficult to pin down. [In the recently published study (January, 2002) of Dervay and Powell (aka Dr Deco) in Aviation Space and Environmental Medicine , test subjects performed exercise and than were depressurized to altitude. Ten of the twenty never produced gas bubbles even when the exercise was done just five minutes before depressurization. Why? I would love to know too.]

Following that comes controllable variables such as exercise (musculoskeletal stress), physical fitness (often measured by maximum oxygen uptake while exercising), fast ascents (bubble dynamics problems), and hydration level (probably determining the body’s surfactant concentration and thus surface tension).

The dive computers are not putting one on the “edge” since that concept is not physically real. DCS is not an all-or-none response. There is not a sharp bends/no-bends point for a group of divers.

Divers must remember that increased gas loads increase the possibility of DCS and there is not a true, safe limit. Probably the day will come when we will know more about this strange disorder - - but that day has not yet come.

Dr Deco :box:

 

[Aquamore]

Where as I am totally in concurrence with your stated points, I would also be interested to hear your views after considering the following.

Do you agree that 'undeserved hits, can also be the product of divers staying withing the limits of the Tables (or Computers algorythm) but there may have been extra gas saturation due to our old friend Adiabatic compression (i.e. pressure changes due to several short ascents followed by descents which the tables and computers do not make allowances for) like a bicycle pump compressing already compressed gas into the tissues? This does not allow the gas to be dissapated quick enough before the next compression cycle comes along, the effect is cumulative.

Another classic case of this is were divers do considerable length decompression stops, at say a depth 6 Metres, on a static shot line and there is 3 metre swell of the ocean. So at one moment there is 1.9 bar of pressure above their heads and in the next moment 1.3 bar of pressure.

This delta of a changing 0.6 bars of pressure (over half of the earths total Atmospheric pressure at sea level) is not accounted for, (not even in Professor Buehlman of Zurichs tables), and I doubt if a computer algorythm has been produced to take this into consideration as there is no table I am aware of that can calculate Adiabatic compression in real time.

I believe not all fast tissues and slow tissues absorb gas at the same rate in every diver and you have already clearly indicated individuality (fitness), weight and age play a role here.

I am suggesting that the dissipation of gasses in the slower tissues at the end of a long dive is also different for each diver so the constant bicycle effect of Adiabatic compression from numerous changes in ambient pressure can also take their tole?

I hope you can understand my point here as I am not very good when it comes to serious discussion. Sorry.

Aquamore

 

[blacknet]

Aquamore,

No one deserves to get bent (well other than that dir loudmouth spokesperson).

Ed

 

[Lost Yooper]

Thanks to him, I don't get bent anymore .



Mike

 

[blacknet]

Hello,

Uhm anymore? Exactly how many times have you been bent anyway? oh and btw prison doesn't count (Just kidding)

Ed

 

[Aquamore]

.... and I would like to hear what Dr Deco' opinion is about this anomaly.

Free Speech for all!

Aquamore