Safety stops

[CIMI Diver]

I am curious, would doing your 15' safety stop breathing pure O2 decrease you chance getting hit with DCI.

 

[Rick Murchison]

I am curious, would doing your 15' safety stop breathing pure O2 decrease you chance getting hit with DCI.

The short answer is "yes."
But then on a recreational profile you'd be taking your chances of DCS from "all but non-existent" to "less than all but non-existent"
Rick

 

[clarktenk]

I am curious, would doing your 15' safety stop breathing pure O2 decrease you chance getting hit with DCI.

If you are following a recreational profile why would you need to? Would it increase your margin of safety? Yes it would as well as work towards minimizing your requird surface interval.

The reality of your question though is that this type of diving starts to delve into the technical range and does require some proper training on deco procedures for your safety.

You are on the right line of thinking though and I would reccomend you start looking into doubles, back plate and wing. You don't have to be technically trained to start diving doubles but I would reccomend finding soemone that knows what they are talking about to mentor you as to the proper gear configuraion and why it is setup that way.

good luck

 

[BlueDevil]

A better (or at least more convenient) option for recreational diving is to do a deep safety stop, followed by your normal safety step. NAUI suggest 1-2 min at half your maximum depth. The DAN Europe website has some interesting research that supports this approach

 

[wedivebc]

Carrying a gas that is toxic below 20ft has other risks involved and the safety you may or may not receive from it's use is far outweighed by the risk involved from breathing pure O2 at depth. This is not a decision to be taken lightly.

 

[Dr Deco]

Hello CIMI diver:

Dr D. was away from the JSC office for a while on NASA business. We were discussing decompression on the Moon. This is definitely cool!

The short answer is “Yes.” That has been said already.

However, there are ways to improve your chances such as slow ascents, minimal straining when reboarding the dive boat, in addition to limiting the nitrogen dose.

There is much truth that adding another “something” simply adds complexity. NASA is always watching to avoid the addition of complexity. When something is difficult, one often does not do themself a favor by increasing the complexity.

It is a good question, though.

Dr Deco :doctor:

 

[Zero]

Hello CIMI diver:

Dr D. was away from the JSC office for a while on NASA business. We were discussing decompression on the Moon. This is definitely cool!

.... Hey Dr. D. why don't you help NASA solve that foam wrinkle, so some of us can continue with our research on the ISS!

Cheers,

Zero

 

[DA Aquamaster]

In terms feeling better after multiday repetetive dives near or in excess of the NDL's (with appropriate deco stops), I have found that slower ascent rates and deep stops do as good as or better job than even a nitrox mix or pure 02 for accellerated deco. I'll also second the concern that having a high 02 percentage gas along creates additional risk and complexity and should not be done without both proper training and good reason.

If both conditions are met, in light of the advantages of deep stops, you might conclude that 50% is a better choice as you could use it for the entire ascent starting with any deep stop at 70' or less. It would also serve as a redundant bail out gas at any depth less than or equal to 70 ft, so it would do double duty for you in many cases.

On a recreational dive (without any deco gas) I will normally do a deep stop at about 1/2 max depth and then ascend slowly, and often in steps, from there to a 3 minute safety stop at 20 ft.

In terms of your overall dive profile, doing the deep stuff first with a slow and gradual ascent to the surface over the course of the rest of the dive would be perfect. So I try to recreate that curve as much as possible within the limits of a given dive site.

 

[DA Aquamaster]

.... Hey Dr. D. why don't you help NASA solve that foam wrinkle, so some of us can continue with our research on the ISS!

Excuse the highjack... It's ironic that Dr. D used the NASA avoid "complexity" argument.

After all, we had the world's premier heavy lift vehicle series that was not only extemely capable but also comparatively simple and inexpensive, particularly given the existing infastrucure and economy of scale that could have been eveloped. But none the less we dropped the Saturn V/Saturn IB/Apollo CSM systems in favor of the extremely complex and inefficent space shuttle. As a result of our poor judgement in not at least keeping the Saturn program alive along side the shuttle, we not only lost the ability to put a man on the moon but we sacrificed the ability to put an extremely large and heavy payload into earth orbit as well as the and the ability to make numerous launches in rapid succession. And with the cost of replacing the external tank and the even higher cost and complexity of refurbishing the shuttle's reuseable components between flights, we didn't even save any money.

We would have been better off developing a partially resuseable manned spaceflight system based on the Saturn/Apollo system. It was suggested at the time that the Saturn first stage's overly robust F-1 main engine could have been reused for at least five flights which would have made a recovery system for the first stage a very attractive and economical prospect.

The ultimate irony is that the leading proposal for NASA's next manned vehicle looks a lot like an Apollo CSM perched on top of a conventional booster design and is probably about where we would have been 20 years ago if we had not gone high tech and put all our eggs in the shuttle basket. Given that this proposed vehicle will not be in service for another 7 years, I figure we have lost about 27 years of progress due to shuttle development.

To be fair, it was not entirely NASA's decision to kill the Apollo Saturn and go only with the shuttle program and much of what happened was due to budget cuts, but the people, adminstrators and politicians who brought that about did us a grave disservice.

 

[Dr Deco]

Hello Aquamaster:

My recent comment on “lack of complexity” was based on recent experience of mine at a NASA conference on Lunar Exploration and Surface EVA. As far as the other parts of NASA are concerned, there is often too much complexity.

Yes indeed, you have pointed out that “the emperor is not wearing any clothes.” What you have written about the Shuttle is correct. [While I am still a NASA employee, and accepting their money, I will not get into “NASA bashing.”]:14:

I would point out, as you did, that many decisions concerning space operations come from Congress and not NASA Headquarters.

Dr Deco :doctor: