Blow-n-go emergency ascent question

[Deac in the Wake]

We've been pondering this a while and figured this is the place to ask- and it's as close to finding out as we're interested in.

Assume that you're down non-deco (say 40-50 feet) and you find you're out of air- not low, but out (for whatever reason). Assume you've been down for 50-60 minutes at said depth.

Your dive buddy isn't close enough to intervene so you drop weights and head straight for the surface. After a few minutes at the surface (say 5 minutes), either your buddy or another diver swims to you.

Assuming they have sufficient air, is there any benefit to getting their octo and descending to 15 feet for a safety stop?

Let's say you emergency ascend right next to the boat and another diver immediately gets with you as you surface. Should you proceed to exit onto the boat or is there anything gained by securing another air source and returning down the safety line/bar to 15 feet?

 

[Jafo123]

I would get on the boat and tell someone what happened so they can have the Oxygen standing buy and can keep an eye on you. Maybe do a assement to make sure your OK.

 

[Doc Intrepid]

The good doctor will have more in-depth answer (no pun intended), however, primary issues you might encounter would be caused by bubbles forming in your blood (because they cannot offgas rapidly enough).

To avoid said issues, these bubbles would need to be driven back into solution.

To force the bubbles back into solution, you would need to go much deeper than 15'.

In - water recompression is not a recommended procedure.

Ergo, you would gain very little from descending to 15' after surfacing.

Getting on the boat, remaining calm and not real active, and going on oxygen, would all be approaches that may be wise.

The idea is to prevent the bubbles from forming in the first place, not to deal with them after they form. (If you want to get technical we can talk about seed bubbles, filtration, and different variables that determine rates of decompression - e.g. there are approaches that may be described as 'dealing with (micro) bubbles', but the above represents an over-simplified and general response.)

FWIW. YMMV.

Doc

 

[TSandM]

Your likelihood of DCS is low, but if it does occur, it is best not to be in the water when it happens. Should you, for example, begin to become paralyzed, it is better to be already on the boat than to be in the water with someone who probably has never handled a rescue, and now has an incapacitated diver to manage.

 

[dpbishop]

Second what TSandM said. I know of a very experienced diver in San Diego who died as a result of just that; grabbed a new tank, went down to decompress and never surfaced.

 

[fisheater]

It worked every time on Sea Hunt.

Not so much in the real world. All the training agencies that I'm aware of, say that in-water recompression is a major no-no.

Evaluate, oxygenate and evacuate.

 

[Dr Deco]

Hello In the Wake:

If you are below the NDL, and you are in your example, there is no need for a safety stop. In a case of missed decompression, it is best to simply stay on the boat and breathe oxygen if it is available. Tables have generous limits and you should not have a problem.

Depending on how much deco was missed, it might be wise to notify someone and head for shore. This should not be a problem that presents itself in recreational (ie, NDL) diving.

Bad Choice

There was a case in Southern California a few years ago where a diver believed that she was in need of a few minutes of deco time in the water. She hastily reentered the water and in the midst of her haste, she drowned. Very sad - and needless.

Dr Deco :doctor:

 

[Saturation]

Hello In the Wake:

If you are below the NDL, and you are in your example, there is no need for a safety stop. In a case of missed decompression, it is best to simply stay on the boat and breathe oxygen if it is available. Tables have generous limits and you should not have a problem.

Depending on how much deco was missed, it might be wise to notify someone and head for shore. This should not be a problem that presents itself in recreational (ie, NDL) diving.

Bad Choice

There was a case in Southern California a few years ago where a diver believed that she was in need of a few minutes of deco time in the water. She hastily reentered the water and in the midst of her haste, she drowned. Very sad - and needless.

Dr Deco :doctor:

Hi Dr D:

I concur with your advise, especially on recreational dives. On the accident in S. Ca, I haven't heard of any recently, but the most infamous one was made public, the case of Mia Tegner, from Scripps. Is this it?

 

[eponym]

Good consensus. Scuba-doc.com has a powerpoint piece on accident management which recommends all of the following be avaiable for a safe in-water recompression:

full-face mask; oxygen breathing system; adequate supplies of oxygen;
cradle, chair or platform that can be lowered to the desired depth;
warm, calm water without current and dangerous marine animals​

While one could call this list overkill, I wouldn't want to manage a possibly hit diver recompression with anything less. Just keeping a reg in your mouth can be a problem when symptoms develop.

-Bryan

 

[DARREN PROUTY]

This did happen to me three months ago after ninth dive on live aboard boat in s. Cal. I felt fine for 10 min. Till i had back pain and paralized from waist down. Crew put me on oxygen and felt better. Coast gaurd then flew me to ucla for a 6 hour chamber expirience. My left leg is still numb can you say wake up call i did