So why is it a bad idea to go back to do a safety stop if you blow it?

[TSandM]

The biggest reason for not descending to do a stop, if you have blown your ascent, is that, if you DO become symptomatic while in the water, you may never make it out. If you become paralyzed while you are doing your omitted deco, you may not even make it to the surface to let anyone know. If you are developing DCS, you are far better on the surface, boat or shore, where you can be put on oxygen and transport to a chamber can rapidly be arranged.

People who do high-risk diving in very remote places sometimes set up protocols for doing omitted decompression; they involve additional gas supplies, full face masks, and support divers.

The first answer put it succinctly: If you don't develop symptoms, you're fine on the boat; if you do develop symptoms, you're safer on the boat. And an ounce of prevention is worth a pound of cure, which is why folks should practice emergency procedures like air-sharing and master buoyancy control while task-loaded.

 

[waterpirate]

Agree that there is a huge differance between missed safety stops, and blown deco. My suggestion would be to advocate the use of o2 on boat/on surface rather than re-enter the water in the case of missed safety stop. In the case of blown deco it's all about location and severity of the situation.
Eric

 

[ianr33]

Agree that there is a huge differance between missed safety stops, and blown deco. My suggestion would be to advocate the use of o2 on boat/on surface rather than re-enter the water in the case of missed safety stop. In the case of blown deco it's all about location and severity of the situation.
Eric

Why would you go on O2 if you missed a totally OPTIONAL stop?

 

[MXGratefulDiver]

Why would you go on O2 if you missed a totally OPTIONAL stop?

I would ... as a precaution ... if it were available and there was no risk of needing it for subsequent divers at the time.

Oxygen is cheap insurance ...

... Bob (Grateful Diver)

 

[danvolker]

What's the technical reason for not going back down to finish a safety stop if you happen to blow it? Say you ascended way too fast from 130ft, or even greater, and blew through safety stops. Why is it a bad idea to immediately go back down and do more safety stops, assuming nothing is stopping you from being able to go back down and do them?

I disagree with alot of these responses, and the mainstream agency position.

However, there are few good reasons for blowing your stop to the surface from a 130 foot dive.....
let's pretend for a second you had your inflator fail and fully inflate your BC while you were holding your $10,000 camera/lens and housing, and with one hand, you were not able to quickly disconnect in time to stop your freight train to the surface ascent..... Or some other similar situation.

The reality is, if you ARE not a moron without skills, you will be safe to swim back down to 30 feet, better to 50, and then do a slow normal ascent, with a long stop. This will only be true if you do this IMMEDIATELY after surfacing...you cant wait 2 or 3 minutes.

From a sudden freight train ride up, your blood will NOT fiz or hypersaturate instantly--you "should have" one to 2 minutes. If you instantly disconnect the inflator, dump your bc and go quickly ( but without big exertion of course--let the dumped bc get you down fast) down to 50 or 60 feet, you should be able to complete the dive as if nothing major had happened. I'd still run a very slow ascent 50 for 2 minutes..then 40 for a minute, then 30 for a minute, and 20 same, and then hold 10 for 3 to 5. You should be fine.

A diver who waited 5 minutes--had to get on the boat to get another tank....would likely already be fizzing like a coke bottle just opened. They would be unlikely to benefit from the return to depth unless they could go down on their air, then at 20 feet switch to pure 100% O2, which they could do for 10 minutes at 20 feet, then surface on the 02 and stay on it aboard the boat till the tank empties.

Since divers without good skills can't be trusted to dive with a 100% O2 tank ( because they can't sink lowwer than 30 feet without it gwetting dangerous for toxicity) , this option is open only to tech divers with the right skills, or GUE fundies divers

 

[ScubaFeenD]

From what I understand, 100% O2 on a boat is far better than some 21%-36% mix that a rec diver would be breathing even if it is at 15'.

 

[MXGratefulDiver]

Since divers without good skills can't be trusted to dive with a 100% O2 tank ( because they can't sink lowwer than 30 feet without it gwetting dangerous for toxicity) , this option is open only to tech divers with the right skills, or GUE fundies divers

I'd take issue with the assumption that recreationally-trained divers couldn't be trusted to hold a stop as you described ... anyone who has taken my AOW class will have demonstrated that ability before they'd be able to complete the class. In fact, they'll be holding stops as appropriate to do designated tasks like taking compass headings, air sharing, or shooting a bag. Any recreational diver is perfectly capable of learning these skills without taking GUE Fundies or tech classes.

I think it would be more appropriate to state that unless you've been trained in the proper use of oxygen for in-water decompression, it'd be a good idea not to ...

... Bob (Grateful Diver)

 

[danvolker]

Bob,
If one of the OPen water certified spearfisherman I dive with on charter boats in Palm beach, had an incident as described, where they got blown to the surface, my solution would be to jump in with them and monitor the oxygen for the deco.....but any of these spearfishing ow certified divers would have the skills to hold the stop and follow the directions....
As to a course on this, c'mon You tell them to breathe it down to 20 feet, stay there at least 10 minutes, if they have pains stills, go on air for the next ten, then back to O2 for ten more, then surface on O2 and stay on it. simple instructions--if they cant just follow these, they are not smart enough to dive....They dont need a course on it.
Your students Bob, are likely to be much better than the "average" student, and that is where I have to make comments as I did, about a recreationally trained diver.
Here in Palm Beach, there is a large range of instructor talent, as their is everywhere. The students that just went through a "Groupon" class, absolutely should not be expected to have the skills to hold the stop at 20 feet.

 

[danvolker]

From what I understand, 100% O2 on a boat is far better than some 21%-36% mix that a rec diver would be breathing even if it is at 15'.

You are correct ScubaFeend
Even 80-20 is pointless on the boat...they would need 100% O2 on the boat, or at 20 feet. The Gradient of 80-20 (oxygen at 80%) is "insufficient" to be effective at removing the bubles, and the typical 34 or 36 percent niytrox even more useless for this.

 

[captain]

Take the safety stop with this cravat. Tens of thousands of NDL dives were done in the past with no safety stops and the then 60 feet per minute accent rate.
Just like now sometimes divers exceed the 30 feet per minute accent rate divers sometimes exceeded the 60 feet per minute accent rate. The safety stop was instituted to slow down the divers that exceeded the 60 FPM rate. The accent rate was change to 30 FPM but the safety stop was never eliminated.