Ascending faster than 60ft/minute

[akbpilot]

If what you report is true, then it's instructors making up for an agency short coming.

Not having experience with different diving agencies, I can't comment on any others, but I would hope any instructor would make up for any shortcomings in any agency. I realize that's probably not the case, but that's what I would hope for.

The closest I can come to a training comparison is my basic flight training. My first instructor went through everything in the syllabus methodicaly, checking all the boxes, dotting all the "i's" and crossing all the "t's". At that point he could have signed me off the take the FAA flight check, and I would have been a "Pilot". Instead he said, " Now that we have all that crap out of the way, let's go learn to fly." Another 20 hours of real world.

That's kind of the way I feel about my dive training, learned what was in the book, learned some real world too.

 

[Walter]

I would hope any instructor would make up for any shortcomings in any agency.

I would hope so as well, but an even better concept would be to eliminate the agency shortcomings. Giving an example of an agency shortcoming, then repeating that grossly untrue mantra makes absolutely no sense.

 

[Walter]

Take a bottle of Cola and open it... Those bubbles you see are exactly what can happen in your blood if you go too fast! Now ask yourself what happens if those bubbles go somewhere and get blocked (and you are still surfacing)...

Just take it slow...

Not just the blood, but in all the tissues.

 

[Fireman Ken]

Slower is better, especially as you get up to the last 33 feet from a deep dive (within 1 atmostphere of the surface). As other replies have said, fast ascent is a big contributing factor to DCS (the bends). The good news is that there are many factors that bring on DCS. The bad news is these factors effect different divers differently. Dive tables and computers are based on models; some better tested empirically than others. Ascent rates is one DCS factor that you, the diver have control over. The deeper you go and the more N2 that gets aborbed into your tissue compartments, the more important slow ascents become in terms of off-loading N2.

The reason I like shooting liftbags when I ascend from a technical dive is that the bag drastically slows me down on my ascent. Anchor lines and sloping underwater topography are also helpful, if present. The golden rule to remember is don't ascend any faster than your smallest bubbles. This is good, sound advice and must be practiced on the most elementary of dives.

My two cents.

Ken C

 

[bfisher]

Fast ascents increase the risk of the bends (DCS).

Are you sure you mean the "Bend"? I am under the impression that rising too fast can cause Lung Overexpansion----air embolism.

 

[TSandM]

Ascending too fast with a closed glottis can cause lung overexpansion -- pneumothorax or air embolism.

Ascending too fast, period, can cause decompression sickness from excessive bubbling (aka the bends).

 

[Thalassamania]

Not to be a stickler for exactness, but given that the topic is one that can affect people's lives ...

Ascending too fast with a closed glottis can cause lung overexpansion -- pneumothorax or air embolism.

NO! The speed is irrelevant. AGE is caused by introducing air into the arterial circulation, usually by way of a torn alveolar sac in the lung.

Ascending too fast, period, can cause decompression sickness from excessive bubbling (aka the bends).

YES! ... well sort of. Removing the pressure so fast that the critical super saturation ratio is exceeded and thus bubbling occurs causes DCS. But the converse, (e.g., ascending very slowly helps avoid DCS) may not always be true.

To quote from the DAN article I referenced in my earlier post:

What is interesting, and not necessarily intuitive, is that an in-water stop with a relatively rapid ascent rate appears to be more effective at eliminating inert gas than a very slow ascent rate.

… various empirical strategies have emerged, including - quite recently - the 15- to 20-foot safety stop. It would seem from this discussion, that for deep dives, the shallow stop may be "too little too late" and that an additional deep stop may indeed be necessary to reduce the incidence of DCS in the fast tissues. This would bring us closer to the original 2:1 model of Haldane, which appears more appropriate for the kind of deep, short diving that recreational divers tend to do.

Clearly, the best decompression schedule is … an ascent rate of 33 feet (10 meters) per minute, and two stops at 45 feet (13.5 meters) and 9 feet (2.7 meters) respectively, this profile had the lowest bubble score of 1.76.

The secret of the deep stop rests in the paradigm shift of "beating the bubble" versus "treating the bubble." The former utilizes the deep stop to ensure that the fast tissue critical gas super saturation is not exceeded and stops bubbles from forming in the first place. The long ascent to the 20-foot stop, as is currently done, involves "treating the bubble"; we know this produces 30 percent asymptomatic or so-called "silent bubbles" on the surface, which may be indicators of decompression stress or even potential DCS.

 

[cgvmer]

In the current PADI "Go Dive" (OW book) on page 120 it states "Swim up slowly, at a rate no faster than 18metres/60 feet per minute (slower is fine) while breathing normally"

The copyright was 1999-2004

I started my course in Aug 2005

 

[Charlie99]

Not to be a stickler for exactness, but given that the topic is one that can affect people's lives ...
NO! The speed is irrelevant. AGE is caused by introducing air into the arterial circulation, usually by way of a torn alveolar sac in the lung.

And what's the most common way to get a tron alveolar sac in the lung? Ummmm. How about rapid ascent with closed glottis.

 

[Thalassamania]

Once again, speed is not a relevant factor.

Dives who suffer from an AGE are, likely as not, to be wearing a mask. Does that mean that wearing a mask is a common way to getting an AGE?

The speed of the ascent is only of interest because AGE tends to be associated with panic ascents; and panic ascents are more likely to be performed with a closed glottis.