Why is PADI so conservative?

[Riger]

starting out in any sport it is good to be conservative

after 100 dives, there's not much difference between diving to 60 feet or 120 feet

however, on your first few dives, you are still unsure of how narcosis will affect you at depth, unsure of your skills, and unsure of the environment. the deeper you go, the faster you go through air, so the faster emergencies get out of control.

it's a good thing to progress slowly and give yourself "artificial" limits to begin with as your experience and confidence grows. those limits can be imposed by the agency or be self-imposed.

Good advice, I agree.

 

[Teamcasa]

It's not so much that PADI is conservative but more like dive operations and insurance companies are. They are the ones that enforce PADI's recommendations.

I too agree with Andy on this.

 

[DevonDiver]

after 100 dives, there's not much difference between diving to 60 feet or 120 feet

Except for...

1. Inert Gas Narcosis (Nitrogen partial pressure rises from 2.21 to 2.84)

2. Increased Air Consumption (2.8x SAC to 3.6x SAC)

3. Decreased No-Stop times.

4. Increased breathing resistance (2.8x air density to 3.6x air density)

5. Emergency ascent to the surface time doubles (1min to 2 min @18mpm or 2min to 4min @9mpm).

Of course...none of these factors is particularly tangible unless something goes wrong...

..and then you learn how the increased narcosis will kick into effect as your breathing rate increases dues to stress...and how the increased breathing rate will suck down your gas seemingly exponentially...and how your delayed reaction times and perceptual narrowing mean you over-stay your no-stop time...and how you can't complete any (emergency) decompression because your tank is nearly empty...and how faaaaaaaaaaar it is to the surface when you realise that ACTUALLY you ARE completely out of your depth....and about to become a statistic.

There doesn't seem to be any difference between 60ft and 120ft.

 

[Diver0001]

he said that with ssi it isint this way at all,

I'm not 100% sure but I'm pretty sure that he lied to you about that. SSI is more or less a PADI clone and as far as I know it only differs enough to avoid getting sued by PADI.

he said that the way he done it was to have a check dive then to see the skills of the diver and then make the decision as to what dives they are able to do

This may be true but it's independent of the recommendations of the training agency.

whats the differance between diving to 18m and to 30m

Well... I guess you could say that the difference is how fast things can get pear shaped and how pear shaped they can get. For example, if you lose your bearings at 18 metres and have to swim a long way back to a sloping shoreline using a compass then you might have 30-40 minutes to do that before you get over your NDL and the problems start to snowball. At 30 metres, you might have 5-10 minutes to get your self sorted. That's why people say your skills need to be a bit better when you start diving deep. Being deep isn't such a problem in and of itself. But being deep when things start going wrong puts you straight into time pressure. And I would say that this is the main difference.

R..

 

[Indian Valley Scuba]

Nice analysis & summary, Andy.

Back to the original question, I concur.

In general, open water diver training courses are developed with a couple of factors in mind. First of all is safety, but from an agency's point of view, so is marketability. You could, of course, design that "Uber-diver" training program that might take 6 months to complete and require 100 dives for certification, and of course, the graduates would cleary be more educated, more experienced, and hopefully more competant than a diver graduating from a four week or even a long weekend course. But, how could you sell this? You have to keep the reality of the market in mind when building a "product" for sale, so for open water divers, - you can only learn so much in an open water course of any agency, and that is why there is a myriad of continuing education programs offered in the industry.

Let's get wet first, have some fun, be safe, and find out how cool diving really is. Then we can get serious about advancing our skills, education and experience, especially when we can see how they will be applied. That last part is key to any educational program - if the participant sees the need and value, they learn a lot better than someone who merely attends.

 

[DevonDiver]

whats the differance between diving to 18m and to 30m,

Just consider one issue...Air Consumption.

If you had an air consumption at the surface of 20 litres per minute.

At 18m, this would mean you consumed 56 litres per minute.

At 30m, you would consume 80 litres per minute.

If you use a 12 litre tank @ 200 bar, you have 2400 litres of air.

This means you have a maximum (forgetting reserves) of 42.3 minutes at 18m and 30 minutes at 30m.

However, if you had a problem and began to hyperventilate due to stress, your breathing rate could easily rise by a factor of 4 (and that is a conservative estimation).

This would mean that..

Your air consumption on the surface would rise to 80 litres per minute.

Your air consumption at 18m would be 224 litres per minute.

Your air consumption at 30m would be 320 litres per minute.

Now, your 12 litre tank @ 200 bar would last you only 7.5 minutes at 30m.

...and that is assuming your tank was full at the time of the crisis.

If your tank was at 100bar when the ***** hit the fan, you would only have 3 minutes and 45 seconds of air.

Now...remember...you have a problem to deal with..the one that stressed you in the first place.... and the increased carbon dioxide retention starts to rapidly bring narcosis problems (slowing down your thinking)...your awareness becomes minimal...you get 'tunnel vision' on the problem that your fuzzy narcosis muddled head is trying to deal with....you don't check your air...

next thing you know...you have a 30m cesa to the surface....

...except you are already panicked, CO2 ridden, confused, out-of-breath...AND LOADED WITH NITROGEN......

Do you reckon you would get up?

If you did get up....do you reckon your ascent would be slow enough to keep you out of a recompression chamber?

If you're unsure....then perhaps the time has come to start treating deep diving with a minimum of respect...and understand why the agencies recommend you get the training, knowledge and experience to safely enjoy diving at those depths...

 

[RJP]

whats the difference between diving to 18m and to 30m?

If you don't know the answer to that question, you shouldn't be diving at all.

 

[Diver0001]

If you don't know the answer to that question, you shouldn't be diving at all.

I don't like these kinds of answers at all. If everyone reacted to trying new things like this we'd still be relying on lightning to give us fire.

R..

 

[D_B]

Yep, that's not very helpful ...
RJP ... please see DevonDiver's post on how to post a helpful post in basic scuba discussions

 

[H2Andy]

There doesn't seem to be any difference between 60ft and 120ft.

stop showing off your vast knowledge and try to help the original poster

after 100 dives, as i said, all those factors are negligible and there isn't much difference between a dive between 60 and 120 feet (that was my statement)

while you are learning, those differences can be a big deal, hence the arbitrary limits agencies place on their various certs

....then perhaps the time has come to start treating deep diving with a minimum of respect...

this is very disrespectful to the poster and very arrogant of you

what gives you the right to decide that the poster doesn't treat deep diving "with a minimum of respect?"

all he did was ask a question, and a good one, so get off his case