PADI vs BSAC

[Janos]

And note the forum

Arising out of Gledders thread, I thought I'd compare the PADI RDP to BSAC 88s. I know that 88s have a reputation for being aggressive, and to be fair, I dive a lot more conservatively than either of the PADI or BSAC tables. However I thought that a side-by-side comparison of no-stop times might be useful. I've assumed a 15m/min ascent rate for BSAC tables. Obviously this is quite high, and if you have a slower ascent rate then the no-stop times (for the BSAC tables) are reduced.

.. . Padi BSAC
20m 44 -
21m - 36
22m 36 -
24m - 28
25m 28 -
27m - 22
30m 19 18
33m - 15
35m 13 -
36m - 12
39m - 10
40m 8 -
42m 7 9

So pretty much the same. Although PADI are every so slightly more agressive above 30m and BSAC are a bit more aggressive below.

Janos

[Clare Gledhill]

Janos - you and I have discussed this off the boards and I'm sorry that the other thread appeared to turn into a bash the BSAC 88 tables debate.

I had to learn how to use the PADI wheel last week (don't ask) and was stunned at how aggressive it appeared to be.

I personally don't want to follow such profiles but it has to be said that loads of divers have followed both of these tables and survived hundreds of 1,000s of dives.

TBH it's the ascent rate which frightens me the most. Mind you, Al Frase and I faff so much that we are lucky to get going at all sometimes

[Janos]

Originally Posted by Gledders

Janos - you and I have discussed this off the boards and I'm sorry that the other thread appeared to turn into a bash the BSAC 88 tables debate.

Nah, don't worry about it. I have thicker skin than that! I didn't take it as a bash BSAC at all. It's more that these things have a habit of getting repeated and repeated and then suddenly they're gospel.

Janos (who's hugely in favour of 6m/min ascent rates.)

[Alun]

I've never dived with anyone who has (deliberately) ascended anywhere near that fast. In fact, one woman in our club who has been a bsac diver for the last 20 odd years, was taught to "...never ascend faster than your smallest exhaust bubbles"

I've only dived with a stinger computer and the ascent rate alarm starts going mental if you go up any faster than a crawl.

[dlegros]

Originally Posted by Alun

I've never dived with anyone who has (deliberately) ascended anywhere near that fast. In fact, one woman in our club who has been a bsac diver for the last 20 odd years, was taught to "...never ascend faster than your smallest exhaust bubbles"

I've only dived with a stinger computer and the ascent rate alarm starts going mental if you go up any faster than a crawl.

On the Vyper, the audible alarm kicks in with a spontaneous ascent rate of 12m/min or a sustained rate of 10m/min

Dom

[Fathoms Down]

Originally Posted by Gledders

I had to learn how to use the PADI wheel last week (don't ask) and was stunned at how aggressive it appeared to be.

Try this some time... Plan a multi level dive on the wheel and then run the dive and compare the timings with a Vytec/Vyper (known to be quite conservative computers). You will probably find that there isn't more than one minute's difference between the two.

Does this make the wheel aggressive? No, it just makes it as aggressive as a dive computer. Its just a case of keeping things in perspective and remembering what no-stop diving is all about.

[Mal Bridgeman]

Hi

I can't resist a debate comparing PADI and BSAC without wanting to put the SSI oar into the debate.

Firstly a bit about the PADI tables....which were created as a consequence of a 3 year study and have remained unchanged since then AFAIK. It produced a table which was very suited to the American deep/quick, followed by a shallow/longer style of diving using a "faster" controlling compartment of 60 mins so that in most cases the repetitive dive is done going in as an A diver.

The PADI tables do have a number of caveats though....under certain circumstances, the recommended safety stop becomes compulsory and if certain limits are reached then a min surface interval comes into play.

If diving in cold conditions then the recommendation is to dive as though the depth is 4m deeper than you actually dive.....which makes them look less agressive.

SSI tables are as follows:
7.5m 245mins
9.0m 205mins
10.5m 160mins
12.0m 130mins
15.0m 70mins
18.0m 50mins
21.0m 40mins
24.0m 30mins
27.0m 25mins
30.0m 20mins
33.0m 15mins
36.0m 10mins
39.0m 5mins

These are based on the US Navy Tables with the Doppler limits applied and have a 9m/min ascent rate and optional safety stop regardless of proximity to the table limits....of course it's recommended but never mandatory.

Best Regards
Mal

[Janos]

Originally Posted by Mal Bridgeman

I can't resist a debate comparing PADI and BSAC without wanting to put the SSI oar into the debate.

Feel free mate. I only chose PADI and BSAC because I'm an Advanced Diver with both agencies and have the tables at home.

Originally Posted by Mal Bridgeman

Firstly a bit about the PADI tables....which were created as a consequence of a 3 year study and have remained unchanged since then AFAIK. It produced a table which was very suited to the American deep/quick, followed by a shallow/longer style of diving using a "faster" controlling compartment of 60 mins so that in most cases the repetitive dive is done going in as an A diver.

Anecdotally at least, I think that was the reasoning behind the BSAC tables as well - when they were written dive times were shorter than today because of air and temperature considerations.

Originally Posted by Mal Bridgeman

SSI tables are as follows:
7.5m 245mins
9.0m 205mins
10.5m 160mins
12.0m 130mins
15.0m 70mins
18.0m 50mins
21.0m 40mins
24.0m 30mins
27.0m 25mins
30.0m 20mins
33.0m 15mins
36.0m 10mins
39.0m 5mins

So not a million miles away from 88s. Slightly more bottom time above 30m, and quite a few minutes less at the very deep depths. But it's nice to see the slower ascent times.

Janos

[Moray]

oi! agency bashing and I missed it!

The 9m/min ascent rate is viewed by padi as the fastest safe ascent rate, (equal to Alun's mate's rate of exhalation bubbles. The bubbles are the guide should all other equipment fail.) In other words, not any faster than this, but slower is better.

And good to know that some people (janos e.g.) dive more conservatively than the limits given. Why push it?

my $0.02
moray

[Paul Oliver]

The "No faster then your smallest bubbles" is the fast limit and another useful guide (after all there are some divers out there NOT using computers SHOCK, HORROR )

Its something that is easy to note in an emergency or panicky moment.

I use it as a guide during AAS and CBL lifts - works for me

Edit- In fact yesterday it was the first indicator i noticed that my buddy was dragging me up a bit quick. He was behind me on a released shot line and went up a bit rapid, past me holding the shot line.