Which is it- 60fpm or 30fpm for ascent??

[the sharkman]

I have always heard the 60 ft/min rule, but my computer would freak out if I did that. I like the fact that my computer is very conservative (Vyper) and normally I watch it to keep from ascending any faster than 30 ft/ min.

:guitar:

 

[MonkSeal]

Relative depresure is what can cause the problems. So, it means that ascent speed has to be adjusted to actual depth. However, the best practice is to stay within limit of 9m/min (30ft/min) up to 5m and then (after last stop) to slow down (3m/min or less).

 

[Ber Rabbit]

Once I was told that the 60 fpm ascent rate was based on Navy divers using surface supplied air. Something about 60 fpm was the speed of the winch they used to bring them up

I remember when NAUI changed from 60 fpm to 30 fpm and was told that was based on research. NAUI has now added another "rule" called the "Rule of Halves" I believe. If you dive deeper than 40 feet when you ascend you should do a 1 minute stop at half of your deepest depth then a 3 minute stop at 15 feet.

EX:
Ascent from 90 foot dive has a 1 minute stop at 45 feet and a 3 minute stop at 15 feet.
Ber

 

[Big-t-2538]

When did they come out with that?

And did you dive yesterday? IF so...I hope you enjoyed it?

 

[The Chairman]

can be found here:
Rule of Halves
Well worth the read!

 

[TheDarknessLord]

you can use 30 fpm at deep diving, it is a good speed! you need a lot of time to get out your gases from your tissues, at least 2 min. from one stop deco to another one.
I guess that you and your son are OW, so, I can tell you that for PADI 60 fpm is good enough!

 

[Scuba Chip]

You can easily demonstrate the need for slow ascent rates, right at home. Take two bottles of room temperature soda pop or beer (personally I would rather not waste good beer), preferably bottles that are NOT twist-off caps, but twist-offs will work. Open one bottle very quickly, and notice the amount of CO2 that comes out of solution. Next, open the 2nd bottle, but do it ever so slowly. You will notice much more foaming (more bubbling) from the bottle that is opened quickly. This visual presentation beats any verbal discussion, for demonstrating the need for slow ascent rates. Try it. It works, and makes a lasting impression on any divers present

 

[mdr231]

I've also recently read about the new "rule of halves"
from NAUI. However, PADI is still teaching a 60fpm
ascent rate (at least as of 5 weeks ago!) with recommended,
though optional, 3 minute stop at 15 ft. They do
qualify it as a maximum rate, but there was no
recommendation in the class to take it any slower.

Thanks for all this good information!
Michael

 

[Dr Deco]

Dear Readers:

Slow Opening/Slow Ascents

The soda pop demonstration is a very good one for slow ascents and the effects of Boyle’s Law on micronuclei. When the bottle is opened quickly, the microbubbles expand, the internal pressure from surface tension is reduced and dissolved nitrogen can enter the microbubble. When the bottle is opened slowly, the microbubbles do not “spring” to a larger size, but rather remain small with a high internal “Laplace Pressure.”

Many people believe that they are decompressing the liquid in a soda bottle when it is open slowly. Decompression in the sense that it is used in barophysiology usually refers to the elimination of dissolved gas from tissues to the lungs through the blood stream. Clearly, in the slow opening of a pop bottle, there is no really exchange of gas to the atmosphere. All of the dissolved gas (carbon dioxide, in the case of carbonated beverages) really remains in the bottle.

Dr Deco :doctor:

Please note the next class in Decompression Physiology :grad:
http://wrigley.usc.edu/hyperbaric/advdeco.htm

 

[ColdH20diving]

mdr231 once bubbled...
I've also recently read about the new "rule of halves"
from NAUI. However, PADI is still teaching a 60fpm
ascent rate (at least as of 5 weeks ago!) with recommended,
though optional, 3 minute stop at 15 ft. They do
qualify it as a maximum rate, but there was no
recommendation in the class to take it any slower.

Thanks for all this good information!
Michael

The PADI instructor I work suggests the 30ft per minute ascent rate with the max being 60ft per minute.