copter53
Guest
Dove last night. 60ft started going up. 40ft to 25ft zoomed up by mistake. Stupid on my part. Stayed at 25ft for like ten minutes to make up then took another 5 minutes to get to surface. Whats the rule here?
Making up for a fast ascent.
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What you did is almost exactly what I would have done in similar circumstances... not sure what ZOOM means but you get my drift. I would venture that any "damage" your rapid ascent threatened, was mitigated by the stop you made and the slow ascent to the surface (by the way, A RULE is to make that final leg from the SS to the surface at 3 metres per minute... that's about 10 feet per minute.
DevonDiver
N/A
As Steve said, an extended shallow stop/s once the ascent is arrested is the answer.
As a minimum, I'd double my normal (3min) safety stop... possibly more.
As a minimum, I'd double my normal (3min) safety stop... possibly more.
this is intended to be a question, and is in no way offering advice:
would dropping back down to 40' and starting over with a slow ascent be an option?
It seems to me that there is a delay in bubbles forming during a fast ascent, and dropping back down may prevent formation. Please feel free to correct me if I am way off.
would dropping back down to 40' and starting over with a slow ascent be an option?
It seems to me that there is a delay in bubbles forming during a fast ascent, and dropping back down may prevent formation. Please feel free to correct me if I am way off.
Usually, mate, that would be a tactic employed on a runaway ascent from a little deeper dive. Of course the unknowns are many in this instance including the length of the diver's exposure on the bottom, but a 15-foot rapid ascent in the portion of the water column mentioned here, followed by his action, should be OK.... that said, if you find yourself in a similar situation ever, your suggestion is a very good one as long as you have sufficient gas!
Are we talking 45 feet a minute? 60 feet a minute (the old standard)? Or are we talking balistic missle fast? What was your nitorgen loading? Could you give more information about the dive profile and your nitrogen loading?
Rapid ascent is never a good thing. Keep in mind the between 66 and 33 feet you will see 33% increase in bubble size. Between 33 feet and the surface you you will get a 100% increase (2x) of any bubble. So stopping a rapid ascent as deep as possible is better. But can you un-ring the bell of DCS at that point?
Rapid ascent is never a good thing. Keep in mind the between 66 and 33 feet you will see 33% increase in bubble size. Between 33 feet and the surface you you will get a 100% increase (2x) of any bubble. So stopping a rapid ascent as deep as possible is better. But can you un-ring the bell of DCS at that point?
Why would there be a delay in bubble formation? How much of a delay does a shaken bottle of coke give in forming the bubbles when you releive the pressure of the cap (ascend)?
Nitrogen is held in solution by the pressure, if you ascend slowly the nitrogen comes out of your blood and tissues where it was stored (remembering there are fast, medium and slow storage areas aka tissues at play here) and into the blood possibly as micro bubbles (silent bubbles) and moves to your lungs (a journey that takes approximatly 3 minutes for all your blood to complete, hence the 3 minute safety stop) where it is off gassed. In water re-compression is not recommended for a varity of reasons by any of the BOW certification agencies I am aware of. Returning to depth would be at this point in water recompression as the bubbles (if any) have already formed.
A bottle of coke is a much faster tissue than most of those in the human body so the analogy above is far less than perfect.
There is also the differences in the concepts of omitted decompression versus in water recompression to be considered. An omitted deco procedure is just that - a means to make up the missed deco, while in water recompression suggests in water treatment once you have DCS symptoms. Everyone pretty much agrees the latter is bad as it is hard to do well, requires special equipment and conditions, and if not done properly can make the situation worse. It's generally only used if you are in the middle of no where and a chamber ride is not an option.
However omitted deco procedures are different. Provided you could be back in the water and descend within 5 minutes and were symptom free, the old US Navy omitted decompression procedure was to go back down to 40' for 1/4 of the 10' stop, then ascend to 30' for 1/3 the 10' stop time, then ascend to 20' for 1/2 the 10 ft stop time, then finally ascend to 10' for 1 1/2 times the 10' stop. (the newer US Navy procedure is similar but involves the use of O2 for more effective off gassing.)
To put that in perspective, if you missed a 10' stop for 5 minutes, you'd go to 40 ft for just over a minute, ascend to 30 for a couple more minutes, then go to 20 ft for two and a half minutes (I'd round it up to three minutes), then finally ascend to 10 ft for (rounding up again) an 8 minute stop before making a slow ascent to the surface. Using a 10 ft per minute ascent rate, the whole evolution would take about 20 minutes, so gas could be a factor for a single tank diver.
Either way, the general concept is that you have to go substantially deeper than a missed 10' stop to reduce the size of any bubbles that have formed and then ascend very slowly from there to reflect the reduced off gas efficiency that would accompany any bubble formation that may have occurred.
More to the point however in your case, a procedure DSAT recommends for a missed deco stop in the water, is to re-descend to the stop depth immediately (within 1 minute) then complete the stop plus an additional minute, then complete the deco schedule normally. In the event you can't re-descend, then you'll stay at the next stop for the combined total of both stops and extend the 20' and 10' stops by 1.5 times their normal length.
Given your situation within the NDLs, but violating the required ascent rate, that's pretty much what you did with your slow ascent.
However in your situation, dropping back down from 25' to 40' and starting a slow ascent would have alos been fine, but extending the ascent from 25' to the surface is just as important.
There is also the differences in the concepts of omitted decompression versus in water recompression to be considered. An omitted deco procedure is just that - a means to make up the missed deco, while in water recompression suggests in water treatment once you have DCS symptoms. Everyone pretty much agrees the latter is bad as it is hard to do well, requires special equipment and conditions, and if not done properly can make the situation worse. It's generally only used if you are in the middle of no where and a chamber ride is not an option.
However omitted deco procedures are different. Provided you could be back in the water and descend within 5 minutes and were symptom free, the old US Navy omitted decompression procedure was to go back down to 40' for 1/4 of the 10' stop, then ascend to 30' for 1/3 the 10' stop time, then ascend to 20' for 1/2 the 10 ft stop time, then finally ascend to 10' for 1 1/2 times the 10' stop. (the newer US Navy procedure is similar but involves the use of O2 for more effective off gassing.)
To put that in perspective, if you missed a 10' stop for 5 minutes, you'd go to 40 ft for just over a minute, ascend to 30 for a couple more minutes, then go to 20 ft for two and a half minutes (I'd round it up to three minutes), then finally ascend to 10 ft for (rounding up again) an 8 minute stop before making a slow ascent to the surface. Using a 10 ft per minute ascent rate, the whole evolution would take about 20 minutes, so gas could be a factor for a single tank diver.
Either way, the general concept is that you have to go substantially deeper than a missed 10' stop to reduce the size of any bubbles that have formed and then ascend very slowly from there to reflect the reduced off gas efficiency that would accompany any bubble formation that may have occurred.
More to the point however in your case, a procedure DSAT recommends for a missed deco stop in the water, is to re-descend to the stop depth immediately (within 1 minute) then complete the stop plus an additional minute, then complete the deco schedule normally. In the event you can't re-descend, then you'll stay at the next stop for the combined total of both stops and extend the 20' and 10' stops by 1.5 times their normal length.
Given your situation within the NDLs, but violating the required ascent rate, that's pretty much what you did with your slow ascent.
However in your situation, dropping back down from 25' to 40' and starting a slow ascent would have alos been fine, but extending the ascent from 25' to the surface is just as important.
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sorry, what I meant to say is that it seems to me there is a delay in the damage caused by bubble formation.
I am no expert, and therefore don't have a leg to stand on in this discussion. I always thought of in water recompression as putting someone back in the water that was experiencing dcs symptoms, but in thinking about it, you are right, that my scenario is too.
Would you recommend as the OP did--stay at 25' for an extended period, and then a slow ascent to the surface, and avoid recompression?
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