Safety Stops and old practices

[ozziworld]

I remember when I was first certified in 1987, Safety Stops (5 min.) were recommended only on deep dives (80 ft.) or more. Not much talk about 3 min safety stops on each dive 9to any depth) like is standard now. Twenty years ago, it was not considered unsafe to simply ascend (at normal rate of ascent) from a a typical dive of 40 to 60 ft. without a 3 min. safety stop.

Is the main reason for this the increased number of divers and the potential for DCS? I was thinking about why this would be implemented when the tables being used by computers are generally more conservative as well.

One factor I thought would be legal and so the addition of safety factors since so many divers are now being certified with varying skill and aptitude.

Or is there an actual scientific and medical basis for the requirement of 3 min safety stops?


I just do the same as everybody now and do the 3 min safety stop. Was just curious as to the actual reasons for doing it.

 

[bubble-head]

That's interesting. I was certified around the same time and if memory serves we were taught 3 minutes at 15 feet when diving at any depth. This was through a PADI instructor. I wonder if different agencies were preaching different safety stop measures?

 

[AzAtty]

http://www.diversalertnetwork.org/news/download/marronifinal1888acapcoraut.pdf

 

[diveprof]

More science, more knowledge. Though the tech folks ahve been aware of the benefits of slow ascents/stops for quite some time. DAN now recommends that you spend a couple of minutes at 1/2 of your max depth in addition to your safety stop. I always do at least 5 min safety stops. On some computers (Aeris, Genesis, etc. you can visually see the benefits of an extended safety stop (8 min plus) as the pixels decrease).

 

[tomboyy]

I remember when I was first certified in 1987, Safety Stops (5 min.) were recommended only on deep dives (80 ft.) or more. Not much talk about 3 min safety stops on each dive 9to any depth) like is standard now. Twenty years ago, it was not considered unsafe to simply ascend (at normal rate of ascent) from a a typical dive of 40 to 60 ft. without a 3 min. safety stop.

Is the main reason for this the increased number of divers and the potential for DCS? I was thinking about why this would be implemented when the tables being used by computers are generally more conservative as well.

One factor I thought would be legal and so the addition of safety factors since so many divers are now being certified with varying skill and aptitude.

Or is there an actual scientific and medical basis for the requirement of 3 min safety stops?


I just do the same as everybody now and do the 3 min safety stop. Was just curious as to the actual reasons for doing it.

I don't know the actual reason, but it seems like that as more time passes, the more rules there are.

 

[don Francisco]

Safety stops are simply a way to increase the statistical safety margin. In theory, if you dive within the NDL and factor other variables such as temp, exertion, etc. you should be able to ascend - at a reasonable rate - directly to the surface with an acceptably low risk of DCS.

What's an acceptable risk in some situations, may not be an acceptable risk for everyday practice. Also, since the dive population is aging, and diving in worse general health, the statistical risk is higher that it might have been 20 or more years ago.

Lastly the advent of dive computers is a double edged sword. On the one hand computers should reduce DCS rates by giving divers the info they need to manage their dive profiles. On the flip side computers take away the safety margin afforded by all that rounding up table users do. By giving you credit for fractional depths, and time not at max depth the computer allows you to dive closer to the NDL than you used to and actually increases your DCS risk.

So think of today's safety stop guidelines as a way to get back some of the margin for error that you used to allow when you were in good health and dove conservatively because you didn't have precise data.

 

[ozziworld]

But were people actually getting bent ? I understand the practices that are recommended and accepted now. I was jsut wondering if it was because of divers actually getting hurt because of the absence of the current recommendations.

I believe the 'old timers' who dove when spgs were not even around may have even more to say about developments in scuba training, gear and practices.

Of course a safety factor is added safety. That's a given. Was wondering if the origins were legal or scientific. Has the military added these safety stops as well? They are subject to the same biology and science as all divers. They are however not subject to legal concerns and liability as a dive ' industry'.

 

[Doc]

I believe the 'old timers' who dove when spgs were not even around may have even more to say about developments in scuba training, gear and practices.

Yeah, but nobody believes us.

We dove US Navy tables and did no 15' safety stops. I aint been right in years

the military... added these safety stops as well? They are subject to the same biology and science as all divers.

Except for that "getting blown up" part, yes, they are.

I agree with DonFransisco above. The 15' safety stop was just a yellow line painted in the water column that hopefully everyone who would otherwise blow past deco stops ("needed" or not), it just gave them a reminder to park it and fizzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz

 

[Gene_Hobbs]

Many of you probably know Donna in DAN Research...

Uguccioni, DM. 1994. Doppler Detection of Silent Venous Gas Emboli in Non-Decompression Diving Involving Safety Stops. MS Thesis. University of North Carolina at Wilmington. RRR ID: 3430

Also worth a read if you have not is the AAUS workshop...

Lang, M.A. and G.H. Egstrom (eds.). 1990. Proceedings of the AAUS Biomechanics of Safe Ascents Workshop. Woods Hole, MA. 220p RRR ID: 4241

 

[Nemrod]

Yeah, but nobody believes us.

We dove US Navy tables and did no 15' safety stops. I aint been right in years



Except for that "getting blown up" part, yes, they are.

I agree with DonFransisco above. The 15' safety stop was just a yellow line painted in the water column that hopefully everyone who would otherwise blow past deco stops ("needed" or not), it just gave them a reminder to park it and fizzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzzz

Yes, we did dive to 130 plus feet and make direct ascents at 60FPM without safety stops. Yes, we dived without a spg. Yes we dived without a BC. Yes we knew what we were doing. Obviously we did not die or suffer any negative consequence.

N