Missed Safety Stop. Go Back Down?

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I thought that bubbles form fast (mostly during ascent - where pressure changes are fast - or soon after it), while symptoms can take long time to appear. Well I am obviously wrong. Anyway I'd stay well within NDL for the time being.
Thanks anyway


If you have bubbles formed when you are on the surface, going down makes the bubbles shrink.
 
If you have bubbles formed when you are on the surface, going down makes the bubbles shrink.
Well it does but by going down you also keep adding nitrogen to your blood (assuming you breath air of course - we are at the basic scuba section anyway) and the rate of adding nitrogen (breathing air) is usually far greater than the rate any already formed bubbles would shrink - I think.
Anyway I have reached the limit of my very limited knowledge on the topic. I just follow hopping to learn something new.
Thanks
 
Well it does but by going down you also keep adding nitrogen to your blood (assuming you breath air of course - we are at the basic scuba section anyway) and the rate of adding nitrogen (breathing air) is usually far greater than the rate any already formed bubbles would shrink - I think.
Anyway I have reached the limit of my very limited knowledge on the topic. I just follow hopping to learn something new.
Thanks


If you add more nitrogen is up to a combination of two things, 1. how much nitrogen do you have absorbed. 2. pp of nitrogen in the gas you breath.

If you are on the end of a dive close to NDL you probably have a higher concentration of nitrogen in your body than air at 1.5 atm (5 meter ~ 15 feet) so you still off-gas.
 
Personally, I've yet to see a diver complete a full safety stop.
Wow. As a diver who just doesn't miss a full five-minute safety stop, this alarms me. Just wow.

The OP doesn't suggest why the safety stop was missed. I've blown off 2 minutes of deco for another diver due to two aggressive bulls. Other than that, most of the safety stops I've seen that were missed were due to the diver being out of control. If someone accidentally bops to the surface, they should bop on down and do a 5-minute safety stop as long as they have plenty of gas and there are no other mitigating circumstances. Five minutes of deco will prevent subclinical DCS such as post dive fatigue. Heck, I try to grab as much time floating on the line after my five-minute safety stop before I exert myself going up the ladder. I would love five minutes there, though I rarely get more than a minute or two.

However, if I'm on the boat, I'm not going back in to complete a safety stop. I've done it once for fifteen minutes of deco, but I had to surface to help two injured divers get on their boat. It was a shore dive for me, so I swam back. Yeah, it's a long and embarrassing story, and that's as much as I'm going to reveal.
 
Wow. As a diver who just doesn't miss a full five-minute safety stop, this alarms me. Just wow.

The OP doesn't suggest why the safety stop was missed. I've blown off 2 minutes of deco for another diver due to two aggressive bulls. Other than that, most of the safety stops I've seen that were missed were due to the diver being out of control. If someone accidentally bops to the surface, they should bop on down and do a 5-minute safety stop as long as they have plenty of gas and there are no other mitigating circumstances. Five minutes of deco will prevent subclinical DCS such as post dive fatigue. Heck, I try to grab as much time floating on the line after my five-minute safety stop before I exert myself going up the ladder. I would love five minutes there, though I rarely get more than a minute or two.

However, if I'm on the boat, I'm not going back in to complete a safety stop. I've done it once for fifteen minutes of deco, but I had to surface to help two injured divers get on their boat. It was a shore dive for me, so I swam back. Yeah, it's a long and embarrassing story, and that's as much as I'm going to reveal.

I really dislike it when they come up from below and get under you. They have a tendency of getting you out of the water too quickly sometimes.

13064675_10208125042378115_4232594462699263595_o.jpg
 
If you are on the end of a dive close to NDL you probably have a higher concentration of nitrogen in your body than air at 1.5 atm (5 meter ~ 15 feet) so you still off-gas.

Indeed. My mistake. Cheers
 
I really dislike it when they come up from below and get under you. They have a tendency of getting you out of the water too quickly sometimes.

View attachment 452968
We weren't even spearing. @Marvel @Scuba_Jenny and a few others were on our safety stop. Jenny had a Suunto and had incurred a few minutes of deco. The boat parked on top of us and I believe the sharks were attracted to the shadow thinking they were bottom fishing. They kept rising and circling and we had enough. Time to get out of there.
 
Well it does but by going down you also keep adding nitrogen to your blood
Different tissues in the body on-gas and off-gas at different rates. At 15 feet after a recreational dive, only the very slowest tissues will still on-gas, and those tissues will have so little nitrogen in them at that point that it won't matter. The net effect is off-gassing.
 
Are we all aware of the fact that the DAN video being questioned talked about the scenario where you blow your safety stop, reach the surface, and then descend immediately? It is not talking about reaching the surface, getting back on the boat, looking at your computer, and saying, "You know, I missed a safety stop. I think I will go back into the water and do it now."

That is an entirely different animal.

My computer's manual says if you miss a mandatory deco stop and descend back to stop depth within 2 minutes, it won't trigger a missed deco lock-out. It says nothing about how you spend the 2 minutes. You'd probably be in a bit of a rush, but could potentially get on board, look at the computer, jump back in and get back down in under 2 minutes.

Edit: sounds suspiciously like the kind of rush Mia Tegner was in.
 
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I( somehow missed these comments earlier--reading too quickly I guess.
Personally, I've yet to see a diver complete a full safety stop. Can you believe it? I was shocked after getting certified. The safety pause is what I see in the real world.
Your real world is extremely different from mine. In my two decades of diving, I don't believe I have ever seen a recreational diver consciously stop for a safety stop and not do it all. It might have happened, but if so, I was certainly not aware of it. I am talking about thousands and thousands of divers observed.

Steve, I dive the Florida Gulf Coast. Perhaps my experience is unique because we have a lot of private spearfishing and divers want to get out of the water.
Okay--that explains it.

The spearfishermen in the Gulf Coast have a reputation for being a different breed of diver, although I did not expect that their characteristic behaviors extended to the Florida edge. I thought it was more of a Louisiana thing.

ScubaBoard has a general policy of not deleting threads. It nearly never happens. One of the only times I remember us doing it was in a thread about Gulf Coast spearfishing.

It began discussing a fatality. Two divers had been on a boat fishing all day, enjoying beers as they did. As dusk approached, they decided to go after the fish on scuba, using spears. They put on AL 80s (it was not clear if they were completely or only partially full) and went into the water by an oil rig. One of them decided to go alone after the big groupers that hang out at 200 feet. It was getting pretty dark when he decided to head on down alone. He never returned.

As you might guess, some people participating in the discussion thought the diver had taken some unnecessary risks.

The thread was then flooded with comments by new SB members, all Gulf Coast spearfishers. They insisted that there was absolutely nothing wrong with the dive plan. That's how people dive. Diving is dangerous. Sometimes you die when you dive, even when doing nothing wrong--as was true in this case. In their arguments, they referred to standard diving practices that were standard only to them--nobody else knew what they were talking about. The thread got quite belligerent, so much so that we deleted the whole thing rather than simply shut it down. We thought the many posts advocating dive practices most people consider to be unsafe were violations of one of our ToS--we do not allow the promotion of unsafe practices.

I am not saying all Gulf Coast spearfishers follow different rules from the rest of the world, but some clearly do.
 

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