Adding to a safety stop

[Rooster59]

Hi,

Looking at the deco tables, if you just go over the NDL, it looks like you have a 2 or 3 min stop at 10ft.

I'm in good physical condition, but my age is 56. I've never had any issues with DCS, and I never get real close or go over the NDL. Recreational diving only.

My question is: If I do my 3 min safety stop, at 15-20ft, and then hang at 10 for another 2, am I doing anything meaningful to reduce any chance of DCS similar to an increased "safety factor", or am I just wasting time? I usually have plenty of air left.

Thanks!

 

[Stoo]

"Decompression" is, as you are presumably aware, a well-tested theory, not "fact". Those safety stops are tacked on to reduce the likelihood of a hit. At "your age" (which is younger than my age, so I figure I can say that...) it certainly won't do any harm, and it will further reduce the odds of getting bent. As I commented at a presentation that our own "Doppler" on here made a a few weeks ago... nobody ever died (or got bent) by extending their safety stops.

I don't know what your typical dive is like, but I always figure that the point of "diving", is to dive. When I am someplace warm and sunny, I pretty much hang out in the shallows until I'v sucked my tank "dry". I want to spend as much time in the water as I can. At home, deco stops/safety stops are typically in the mid water column, on an anchor line, in freezing cold water, with nothing to look at other than the bottom of the boat. Even then, I will add several minutes on to my shallowest stop.

If you have other risk factors such as obesity, dehydration, skeleto-muscular injuries, hyper-tension or are dehydrated, tired or otherwise "off", suggest you not consider those extra minutes as "extra" at all. Because you just might save yourself a trip to the chamber!

 

[WarrenZ]

You might also read into deep stops. ~1-2 min stop at half the max depth basically a pause during ascent to off gas a little.

 

[doctormike]

You might also read into deep stops. ~1-2 min stop at half the max depth basically a pause during ascent to off gas a little.

Or on gas a little...

 

[TSandM]

The answer is that you are likely continuing to offgas at that depth, while reaping the benefits of a little compression to control bubble growth. Above 20 feet, you're not doing any harm by sitting, so long as you have gas and the water conditions don't make staying there physically stressful. I will quite often putter around below the boat until the requested time is reached (as I rarely hit min gas) and I've seen some delightful things doing that.

 

[supergaijin]

Short answer: Yes

 

[Steve_C]

If the ocean is calm and the viz is good, I often spend some time hanging out near the hang bar at the end of a dive. Seen a lot of stuff that way. Everything from a big lonely remora which thought I looked like a fat cobia to a 7 ft sand tiger that was lurking high over a wreck. I just make sure that I go up with the last diver to not hold up the boat. [Sometimes my buddy hangs with me. Sometimes they go on up. We have agreed signals for this. I am usually diving in solo configuration such as pony etc and crew, captain, and many of the divers know me]

 

[Lorenzoid]

Another way to look at it is that there are probably all kinds of combinations of depth/time you could add as stops on your ascent even though you are in no-stop territory according to your computer or tables, i.e., so-called "safety stops," but the goal for most of us is to find that sweet spot that strikes an optimal balance of benefit and burden. The problem with that is that there isn't enough data to know what's optimal, and moreover, just how burdensome it is to spend 10 more minutes looking at stuff just under the boat or on a shallow coral head next to the boat is in the eye of the beholder. My understanding is that DAN recommends the 3-minute stop at 15-20 feet as striking a very good balance for the average diver. (If I recall, there's a table somewhere connected with a study that was done to test different combinations of "safety stop" depth and time.) I would think that adding another two minutes at 10 feet as you do would add to the safety margin, but whether it adds enough (you use the word "meaningful") to make it worth the effort (however minor the effort may be) might be difficult to quantify. If it doesn't bother you in the least, then I'd say keep doing it!

 

[Kharon]

You might also read into deep stops. ~1-2 min stop at half the max depth basically a pause during ascent to off gas a little.

Some indications that deep NDL stops increase the chance of DCS. Personally I prefer a long, slow, continuous shallow ascent path (shallow horizontal to vertical) to 15' and then hang around there for 3-5 minutes, from what ever my deepest was. Nothing to back this up. It just works for me/fits my diving style/diving objectives.

 

[Stoo]

Some indications that deep NDL stops increase the chance of DCS. Personally I prefer a long, slow, continuous shallow ascent path (shallow horizontal to vertical) to 15' and then hang around there for 3-5 minutes, from what ever my deepest was. Nothing to back this up. It just works for me/fits my diving style/diving objectives.

There is recent research reported by DAN to support this. In a nutshell... for "recreational" no-deco dives, deep stops may cause more harm than good. A preferred method is, as Kharon suggests, a nice slow and steady ascent rate. For deco dives, it's another story and deep stops might well be desirable.

Since the OP was asking about safety stops and no-deco dives, then deep stops probably are NOT the way to go... especially since the dive itself isn't all that deep presumably.