Ascent Rate (SSI vs PADI)

[Diver0001]

My gf is getting certified through PADI and I looked over the Open Water Diver Manual and compared some of the teachings to SSI, the agency that I was certified with.

To my surprise, the PADI course is much more laid-back and less conservative in comparison to SSI. For example, the PADI manual rate of ascent is double SSI or 60ft/min. SSI is 30/min.

What the book says is in relation to the the RDP. The PADI RDP was tested with an 18m/min ascent rate and therefore the advice PADI gives in the version of the OW book that teaches tables is to not exceed that ascent rate. The book also points out that "slower is fine" although sadly they fail to define how much "slower" is ok, and what the general "best practice" is at this point in time.

IN ADDITION....

Not everyone dives with the tables. If you learn to dive with a computer then the PADI materials that teach you to dive with computer will tell you:

a) read the user's manual for your computer carefully and follow the manufacturer's instructions.
b) ascend in accordance to the manufacturer's advice, which in most cases conforms to the industry best practice of 10m/min.

In other words, what I'm trying to say here is that PADI's advice is relevant and specific to the tools the diver is being taught to use. Different books have different advice. SSI, if I'm reading you correctly, just provides a "one size fits all" answer, which happens to be a perfectly ok approach since it works.

I wouldn't say that one way or the other is more or less "conservative" or "laid back". In both cases, the information is correct and accurate. However, in the case of the PADI materials it is important for the student to be aware of the context in which it is being said. If I understand correctly, SSI avoids the context discussion by giving a general rule; PADI does not and therefore gives specific rules for each tool. Which way is better? Flip a coin. You'll be diving safely either way.

As for teaching it, I am a PADI instructor and when I teach OW I teach 18m/min as MAXIMUM and 10m/min as OPTIMAL when using the tables because I know it's the best practice throughout the industry and that the 10m/min ascent rate does not conflict with using tables. I also teach students various strategies for tightly controlling their ascent rate, which is something that isn't defined well in the book. This is the added value an instructor can have when teaching students how to translate theory (don't exceed a certain ascent rate) into practice (HOW to not exceed a certain ascent rate). Regardless of agency this is the reason you have an instructor and don't just learn diving by reading the book.

R..

 

[Hawkwood]

To continue to belabour the point with respect to PADI and ascent rates;

The PADI OW Manual states: "Ascend slowly - no faster than your dive computer's maximum rate. The maximum ascent rate is 18 metres/60 feet per minute, but most dive computers require a slower rated of 10 metres/30 feet per minute...."

One of the answers to a Knowledge Review Question: "ascending at 18 m/60 ft per minute (or slower if specified by my computer)"

So, we are not teaching that it is an "absolute" that you ascend at 60 feet per minute.

 

[T.C.]

To my surprise, the PADI course is much more laid-back and less conservative in comparison to SSI. For example, the PADI manual rate of ascent is double SSI or 60ft/min. SSI is 30/min.

As is the Navy's.

When I discussed this with a PADI Professional, he said that PADI maintains the 60'/min rate because if PADI lowers it, knowing that 30'/min is safer, would be to admit possible liability and expose them to lawsuits.

Somehow, that just makes sense.

Slower is better. I prefer to ascend at -15 feet per minute.

 

[nv]

I never said I had to do 60 just wondering why the other agencies default to 30


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[Colliam7]

To my surprise, the PADI course is much more laid-back and less conservative in comparison to SSI. For example, the PADI manual rate of ascent is double SSI or 60ft/min. SSI is 30/min.

'No faster than' means just that - you should go no faster than that rate (and the scanned passage even says that); you can always go slower. If you GF actually took the current PADI OW course you would have also read in the manual:

Furthermore, many computers, to my knowledge, would consider 60ft/min a fast ascent and will probably lock you out of further dives.

Really? Which specific computers / algorithms are those - that 'lock you out' of further dives? Some / many may give you an alarm - to let you know that you are ascending faster than might be optimal. But, any computer that would 'lock you out' of further dives because you exceed an ascent rate of 30 FPM is a useless POS and not worth having.

 

[T.C.]

I never said I had to do 60 just wondering why the other agencies default to 30


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I think you mean my post? We were discussing speed limits. Sorry for the confusion.

 

[nv]

No confusion - some genius above kept focusing on the fact that I am using 60 as the default ascent rate and that it can't be altered, when I never suggested that.

Whereby my question is why has padi adopted the 60 while the rest are at 30.

Just so you all know just as I can go slower than 60, I can also exceed it.

I am looking for a supported reason to why they have adopted that 60 and placed it in their material.


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---------- Post added April 22nd, 2014 at 08:18 PM ----------

No confusion - some genius above kept focusing on the fact that I am using 60 as the default ascent rate and that it can't be altered, when I never suggested that.

Whereby my question is why has padi adopted the 60 while the rest are at 30.

Just so you all know just as I can go slower than 60, I can also exceed it.

I am looking for a supported reason to why they have adopted that 60 and placed it in their material.


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[LeadTurn_SD]

No confusion - some genius above kept focusing on the fact that I am using 60 as the default ascent rate and that it can't be altered, when I never suggested that.

Whereby my question is why has padi adopted the 60 while the rest are at 30.

Just so you all know just as I can go slower than 60, I can also exceed it.

I am looking for a supported reason to why they have adopted that 60 and placed it in their material.

Answered by Diver0001 in his post. The PADI RDP is based on the 60' per minute ascent rate, and was extensively tested and validated.

However, a 30' per minute ascent rate was later determined to show lower incidence of asymptomatic bubble formation on doppler ultrasound testing, thus the recommendation to ascend at 30' per minute.

It is a good recommendation.

And again, in recreation diving the ascent rates are "no faster than" ascent rates.

Is 60' per minute too fast?? Divers around the world ascended at 60' per minute (or faster!!) without apparent problems, but the doppler findings were compelling. 30' per minute makes great sense (except on deep dives, but that is not the topic here).

I am from the 60' per minute generation. Were were taught the "slower than your smallest bubbles" ascent rule. From depths approaching 200 feet, we would ascend considerably faster than 60' per minute, then slam on the brakes, and slowly ascend to our deco stop(s).

Use the ascent rate specified by the tables / algorithm / computer / training you use. But 30' per minute, at least near the end of a recreational dive, makes great sense to me.

Best wishes.

 

[nv]

Answered by Diver0001 in his post. The PADI RDP is based on 60' per minute was extensively tested and validated.

However, 30' per minute was later determined to show lower incidence of asymptomatic bubble formation on doppler ultrasound testing, thus the recommendation to recommend 30' per minute. It is a good recommendation.

Is 60' per minute too fast?? Divers around the world ascended at 60' per minute (or faster!!) without apparent problems, but the doppler findings were compelling. 30' per minute makes great sense (except on deep dives, but that is not the topic here).

I am from the 60' per minute generation. Were were taught the "slower than your smallest bubbles" ascent rule. From depths approaching 200 feet, we would ascend considerably faster than 60' per minute, then slam on the brakes, and slowly ascend to our deco stop(s).

Use the ascent rate specified by the tables / algorithm / computer / training you use. But 30' per minute, at least near the end of a recreational dive, makes great sense to me.

Best wishes.

Finally a productive post. You aren't the only one, but thank you


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[T.C.]

Whereby my question is why has padi adopted the 60 while the rest are at 30.I am looking for a supported reason to why they have adopted that 60 and placed it in their material.

That's what it used to be. Why haven't they changed it to reflect the new US Navy standards? As I said; my thought are that PADI maintains the 60'/min rate because if PADI lowers it, knowing that 30'/min is safer, would be to admit possible liability and expose them to lawsuits.