I dont know how right or wrong this sounds but the 3 min safety stop has been around for as long s i can remember. I see tht is is of some use when the tables were very liberal tables, and as such if you were not a navy diver it would e a good idea to stop at 20 for 3 in. For deco purposes the rule could possibly just go away. However keeping it makes one stop at 20 if for nothing else to adjsut the bouyancy and make a concerted search for trafic above. As per my exposure i dont recall recreational diving being deeper than 60 ft being common. Of course it is now 100 ft dives are very common place. I do see to frequently new divers bolting from bottom depth to 20 ft for the 3 min. So it definately had a purpose there. As far as the deep stop go's i think it is appropriate now that so many are doing 100 ft dives. for most the second half depth stop is 20 ft. A couple of yers ago i started to gain an understanding of ration deco and how it compared to other methods including the 1/2 depth stops process. and they all work out about the same as far as results go. The deep stop for me allows me to get my bouyancy in check if needed before heading shallower and the full wet suit starting its greatest gain in lift.i may go to that 1/2 depth at 50-60 ftm till i get to 50' or so and then cut it way back to 15-30ish. Although what i do may not be usefull by somes perspective it has established a routine that can be nothng less than benificial if not a break even.
Two safety stops?
- Thread starter billt4sf
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Bob DBF
Contributor
I may have been doing a deep stop inadverdantly over the years for a completely different reason. When doing an open water ascent, I would stop at 50 or 60' to go over the dive without the help of narcosis and make sure the dive plan I had was the same one I just did. At a time when it was 60fpm to the surface it was mighty handy to know if you went into deco inadverdantly before you broke the surface. Also it was a good time to check the J-valve to see how much air you might have.
When I got my computer in 2005 it started training me to acend @ 30fpm from 60' to the surface, and in 2009 I started doing safety stops when diving with my daughter. Since most of my diving is shore, the upslope has kept me pretty much within these parameters and the new divers I have been buddying with follow these procedures so I do too.
Bob
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Even a blind pig gets an acorn once in a while.
When I got my computer in 2005 it started training me to acend @ 30fpm from 60' to the surface, and in 2009 I started doing safety stops when diving with my daughter. Since most of my diving is shore, the upslope has kept me pretty much within these parameters and the new divers I have been buddying with follow these procedures so I do too.
Bob
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Even a blind pig gets an acorn once in a while.
I did this 20+/- stop in the late 60's. We were taught to do that. Mostly i believe to make a last assesment that it was clear to go to the surface with out getting run over.
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dumpsterDiver
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I cant speek to any agency requirements, Only to the exposure i got. ascend stop look and listen and then surface, but then again we also had to tow a flag on an innertube. As i said before i believe the purpose for the stop has changed over the years but has been there for a long time. Perhaps this is under the ospisis of instructor ability to teach beyond the core content of the agency. Heck we even covered spear fishing regulations. At the time i took my owfd course from ymca deco was not an issue because the ndl could not be reached with a 72 cuft tank. A lot of attention was given t0 the J valve though.
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In my Naui class 1972, there was lots on being able to do free ascent, how to ditch and don, and many skills to present day DM level performance...but zero on a stop....you ascended at the speed of the small bubbles. That was it.
Bob DBF
Contributor
Sounds like the instructor repurposed the kids street crossing mantra, my hat is off to him for a nice peice of work.
I looked in my books from '63 and '80 and didn't find that evolution. Actually, they only said look around, listen and put your arm up if you couldn't see the surface so you would know something was there before you cracked your head. I guess they figured the instructor could provide any helpfull techniques.
If you had two tanks or a set of doubles, all bets were off.
Bob
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Ayisha
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The safety stop was a later invention, but I believe the deep stop was around near the beginning of commercial diving, then was abandoned as unnecessary for recreational divers. Then in the early to mid-2000's, a one minute deep stop (or maybe now it's differentiated for recreational divers as a half-depth stop) started being advocated by DAN and others.
Then in late 2008, the UHMS (Undersea Hyperbaric Medical Society) started advocating increasing the deep stop to 2 - 3 minutes, and discussed this at the 2009 conference in Toronto. DAN, who appeared to recommend 1 minute deep stops, seemed not so sure in it's articles about increasing the time to 2 - 3 minutes, and quite certainly not for technical dives.
That's off the top of my head, I could be slightly off, but I believe that was how things came about to current day recommendations...
Then in late 2008, the UHMS (Undersea Hyperbaric Medical Society) started advocating increasing the deep stop to 2 - 3 minutes, and discussed this at the 2009 conference in Toronto. DAN, who appeared to recommend 1 minute deep stops, seemed not so sure in it's articles about increasing the time to 2 - 3 minutes, and quite certainly not for technical dives.
That's off the top of my head, I could be slightly off, but I believe that was how things came about to current day recommendations...
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To this day, my largest concern on a recreational dive, is the top ten feet.....where I get quiet( so to speak), listen for props and doppler shift if I hear any, and then decide if it is smart to surface....if there is a lot of boat traffic, my 6 feet to surface will be at rocket speed but with wing empty of air, and I will be spinning 360 as I go, and spin-scanning the horizon 360 when I ht the surface...if a boat "was coming", I would be on my way back down at max speed. Since 72, I have had one boat go right over me--one near accident, this by a moron private boater that was supposed to be picking me up--and was running without looking ahead of himself....He was going about 12 mph.... I was so shocked he did not see me and was going to run over me, I actually waited longer than I should have...and actually "pushed off" with my feet/fins on the bottom of his bow..and was rocketing down at emergency speed to 12 feet or so in an instant...that was as close a call as I would ever want to have....Moral of that story is use professional Charter boat captains and boats, not some yahoo that dives and has a boat
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