Deep safety stop question

[Bowzer]

What is the "approved method" of doing a deep safety stop? I have read a lot of conflicting info. The latest Diver Training article seems to be deliberately vague about specifics. I have heard anything over 40 feet or 60 feet. I have heard come 1/2 way to the surface from the deepest point of the dive, come 1/2 way from the deepest to the final safety stop depth. I have heard hang times of 1 to 5 minutes. I have heard that you should deduct your deep stop time from the final stop time, I have heard that you shouldn't deduct your deep stop hang time.
Can anyone provide some clarification?

 

[sea2summit]

Need to dive tables that lay it out for you don't just arbitrarily throw in a deep stop. V-planner does a great job and you can input your safety needs to adjust it on consivative levels. Pretty complicated but a lot of the research indicates that some sort of deep stop is benificial to deco.

 

[Divin'Papaw]

FWIW ... In both my deep and wreck courses I was tought to do a deep stop at 1/2 the max depth for 1 minute on all dives deeper than 80.

 

[diver 85]

Safety stops are in reality optional but very good, cheap insurance......I do a 3 min./15' one on all dives deeper than 40'......deeper dives(greater than 90') I do a onehalf max depth stop for one min...... now saying all this, these are for NDL multi- level stairstep ascending dive profiles.......straight down & straight up deep dives are a different story, much more care is needed in a s-l-o-w ascent rate with 1 min/10' stops taken @ 40', 30', & 20'......

 

[RoyN]

I do one all the time because sometimes I see very interesting stuff and sometimes stuff I shouldn't have seen.

 

[Rick Inman]

Here's something worth reading: http://dir-diver.com/en/knowledge/min_deco_table.html

 

[Bowzer]

As I suspected, there doesn't seem to be a standard answer. NAUI's 1 min at 1/2 the max depth and deduct it from the 20 foot stop, DUI has lots of stops

dive to 100 feet

depth * NAUI * DIR
50 * 1 * 1-2
40 * - * 1
30 * - * 1
20 * 3(2) * 3
10 * - * 3
total * 4(3) * 9-10

It would be nice to follow this and see what shakes out in the future. DAN has published a study but I am not sure how it relates to recreational diving. I don't recall seeing recommendations specific to and usable directly by recreational divers.

If there is indeed a Dr. Decompression, perhaps she will weigh in?

bty, can anyonr tell me how to preserve formatting , the <pre> tag doesn't seem to work here.

 

[DandyDon]

If there is indeed a Dr. Decompression, perhaps she will weigh in?

Lmao - yes, Dr.Deco is real, but he has a real life, too. We are fortunate to have him visit when he can.

 

[nereas]

As I suspected, there doesn't seem to be a standard answer. NAUI's 1 min at 1/2 the max depth and deduct it from the 20 foot stop, DUI has lots of stops

dive to 100 feet

depth * NAUI * DIR
50 * 1 * 1-2
40 * - * 1
30 * - * 1
20 * 3(2) * 3
10 * - * 3
total * 4(3) * 9-10

It would be nice to follow this and see what shakes out in the future. DAN has published a study but I am not sure how it relates to recreational diving. I don't recall seeing recommendations specific to and usable directly by recreational divers.

If there is indeed a Dr. Decompression, perhaps she will weigh in?

bty, can anyonr tell me how to preserve formatting , the <pre> tag doesn't seem to work here.

I suspect that you are ready to buy your own copy of V-Planner (not expensive, only around $100 cheap!) and play with it yourself.

You will see that most dives to not require a deep stop. A deep stop is normally 1/2 the depth of your MOD (max depth) of your dive.

If you plug the deep stop into your dive profile on V-Planner, you will see that it makes no difference to your NDL dive. You will also see that the safety stop is completely optional as well, for any given single dive.

But once you start adding on several repetitive dives to the V-Planner dive plan, then under certain circumstances you will end up with a required stop.

There is no really hard and fast rule. Each different combination of repetitive dives results in different requirements.

Having said all that, I myself always do a 1 minute deep stop at 1/2 of my MOD. Then my next 1 min stop is at 1/2 the distance to the surface. And finally, my 3 min stop is at 15 fsw. Even though V-Planner says that in most cases these stops are purely optional, even with the most conservative features selected with the software. This gives me 5 mins of decompression on every NDL dive. (The modern in-vogue word is off-gassing.)

And yes, there is really a Dr Deco. He is a Ph.D. A genius of sorts, whose math and theory is really hard to follow. I hope you catch his attention, because I will enjoy reading his fascinating reply.

 

[TSandM]

Isn't V-planner essentially pure Buehlmann, and therefore it runs you up shallow before you start deco? You'd have to have a signficant obligation before V-planner would come up with a deep stop.

It's more of a bubble model idea to stop deep. Running you up shallow and then holding you there longer is a way to push the gradient (imagine the pressure pushing nitrogen out of the body). Stopping deeper is done to control bubble formation.

At least that's how I conceptualize it simply. If I'm wrong about V-planner, forgive me. I don't own it.