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

[danvolker]

The idea of blowing the stop from 130 feet as the OP "fabricated" for this discussion, and to go back down---is NOT a safety stop discussion, it is a decompression discussion...and all stops on ascent are deco stops, as you know well... for all of us...Calling them "safety stops" I imagine was to take the dangerous or techy sound out it
In any event, this deco discussion is exactly on point for the OP discussion, and in the context of possibilities for a fairly new diver, this is actually something they SHOULD be reading and trying to figure out their own way of handling if such an issue occurs for them.

 

[captain]

The idea of blowing the stop from 130 feet as the OP "fabricated" for this discussion, and to go back down---is NOT a safety stop discussion, it is a decompression discussion...and all stops on ascent are deco stops, as you know well... for all of us...Calling them "safety stops" I imagine was to take the dangerous or techy sound out it
In any event, this deco discussion is exactly on point for the OP discussion, and in the context of possibilities for a fairly new diver, this is actually something they SHOULD be reading and trying to figure out their own way of handling if such an issue occurs for them.

A new diver trying to figure it out his own way from reading a bunch of techies on here is more dangerous than the missed "safety stop" on an NDL dive.

 

[danvolker]

A new diver trying to figure it out his own way from reading a bunch of techies on here is more dangerous than the missed "safety stop" on an NDL dive.

Agreed..but you are using a typical dive scenario, and the OP came up with a severely different profile that "could" happen to a diver with 50 to 100 dives ( meaning they might find there way onto a 130 foot dive--not saying they should).

I do not think that "with-holding" information is the right way to handle this.
The way I see it, a relatively new diver that has decided to do 130 foot deep dives, better be reading and understanding more than just the core ideas from the Basic Open Water cert.
You can tell them they should not be doing this yet, without more training, but that is not answering the OP question.
If they are smart, they will read lots of info like this, then have "one on one" discussions with a good instructor.

 

[JazzeD]

The OP did not give a BT so I was assuming less than 10 min as he was speaking about safety stop and not deco.
Then your saturation level is so that you do not have a ceiling. So no deco stop just safety stop is suggested but not needed. But would be good to decompress more for a second dive.
If diving more than 10 min BT then a deco stop must be done.
So if safety stop is missed, to answer the question it is not suggested to go back down as like already said in this tread, that lost of other stuff can go wrong.
But you can just increase you SIT time to assist you in your second dive.
If diving with a computer and not entering DECO when a safety stop is missed it will not give any errors or warning.
If entering deco and ascending too quick and hitting the ceiling, you computer will also moan and going back down below and doing stop is a must if conditions allow it.
All of the above calculation is of course on normal air "21%".

 

[captain]

Agreed..but you are using a typical dive scenario, and the OP came up with a severely different profile that "could" happen to a diver with 50 to 100 dives ( meaning they might find there way onto a 130 foot dive--not saying they should).

I do not think that "with-holding" information is the right way to handle this.
The way I see it, a relatively new diver that has decided to do 130 foot deep dives, better be reading and understanding more than just the core ideas from the Basic Open Water cert.
You can tell them they should not be doing this yet, without more training, but that is not answering the OP question.
If they are smart, they will read lots of info like this, then have "one on one" discussions with a good instructor.

It's not about withholding information. it's about presenting information in an inappropriate way and place.

Why is it a severely different profile. If he had chosen 80 feet as his example would the advise be any different, I don't think so.
This is the "basic scuba forum" he got good answers why it 's not a good idea or even much less necessary to go back down to do a missed "safety stop" that is not required to begin with on an NDL dive.
His scenario says way too fast, what does he consider way too fast. He might consider 60 FPM way too fast but actually it is not on an NDL dive.
It might be way too fast by today's standards but it once was the standard and even if you exceeded it that in itself was no guarantee of getting a DCS hit just like following all of today's standards is no guarantee of not getting one.
Muddying up his head with a bunch of tech deco which even all the tech people can't agree on just isn't needed.

 

[danvolker]

It,s not about withholding information. it's about presenting information in an inappropriate way and place.
Why is it a severely different profile. If he had chose 80 feet as his example would the advise be any different, I don't think so.
This is the "basic scuba forum" he got a good answers why it 's not a good idea or even much less necessary to go back down to do a missed "safety stop" that is not required to begin with on an NDL dive. His scenario says way too fast, what does he consider way too fast. He might consider 60 FPM way too fast but actually it is not on an NDL dive.
It might be way too fast by today's standards but it once was the standard and even if you exceeded it that in itself was no guarantee of getting a DCS hit just like following all of today's standards is no guarantee of not getting one.
Muddying up his head with a bunch of tech deco which even all the tech people can't agree on just isn't needed.

Hey, you are forgetting he said he wanted "technical reasons"....That's Carte Blanche for these postings

 

[boulderjohn]

Why is it a severely different profile. If he had chosen 80 feet as his example would the advise be any different, I don't think so.
This is the "basic scuba forum" he got good answers why it 's not a good idea or even much less necessary to go back down to do a missed "safety stop" that is not required to begin with on an NDL dive.

The big difference is that if we are talking PADI, a safety stop is "required" for dives over 100 feet. It is certainly required for 130 foot dives. It is not required for an 80 foot dive unless the diver approaches NDLs. a "required safety stop" sure sounds like a deco stop.

The diver wanted to know if there is a reason not to go down for a safety stop. My point was that if some agencies say that it is a good idea to descend for omitted deco--and they would call a missed stop on a 130 foot dive omitted deco--then it is possible that it is not such a bad idea for a safety stop as well.

 

[divermike1011]

From Rev 6 US Navy Dive Tables:


20‑4.4.2.1 In-Water Recompression Using Air. In-water recompression using air is always less preferable than in-water recompression using oxygen.
 Follow Air Treatment Table 1A as closely as possible.

Use either a full face mask or, preferably, a surface-supplied helmet UBA.

Never recompress a diver in the water using a SCUBA with a mouth piece unless it is the only breathing source available.

Maintain constant communication.

Keep at least one diver with the patient at all times.

Plan carefully for shifting UBAs or cylinders.

Have an ample number of tenders topside.

If the depth is too shallow for full treatment according to Air Treatment Table 1A:

Recompress the patient to the maximum available depth.

Remain at maximum depth for 30 minutes.

Decompress according to Air Treatment Table 1A. Do not use stops shorter than those of Air Treatment Table 1A.
20‑4.4.2.2 In-Water Recompression Using Oxygen. If 100 percent oxygen is available to the diver using an oxygen rebreather, an ORCA, or other device, the following in-water recompression procedure should be used instead of Air Treatment Table 1A:
CHAPTER 20—Diagnosis and Treatment of Decompression Sickness and Arterial Gas Embolism 20-13

Put the stricken diver on the UBA and have the diver purge the apparatus at least three times with oxygen.

Descend to a depth of 30 feet with a standby diver.

Remain at 30 feet, at rest, for 60 minutes for Type I symptoms and 90 minutes for Type II symptoms. Ascend to 20 feet even if symptoms are still present.

Decompress to the surface by taking 60-minute stops at 20 feet and 10 feet.

After surfacing, continue breathing 100 percent oxygen for an additional 3 hours.

If symptoms persist or recur on the surface, arrange for transport to a recompression facility regardless of the delay.
20‑4.4.2.3 Symptoms After In-Water Recompression. The occurrence of Type II symptoms after in-water recompression is an ominous sign and could progress to severe, debilitating decompression sickness. It should be considered life-threatening. Operational considerations and remoteness of the dive site will dictate the speed with which the diver can be evacuated to a recompression facility.

 

[boulderjohn]

I was not talking about in water recompression in my response. I was talking about omitted decompression stops. there is a big difference.

Omitted Decompression: I missed a stop for some reason or other and I have the ability to drop down immediately and do that stop. I have no symptoms of decompression sickness, and I am trying to keep it that way. It is the same preventative measure as a routine deco stop or safety stop.

In-water Recompression: I have surfaced, with or without missing any stops. I may have even completely removed all my gear. I begin to show definite signs of DCS. A decision is made to return me to the water to use the water pressure as a replacement for a recompression chamber.

The two are very different. I view the first as close to routine, and I view the second as a very serious matter that should only be attempted by people who know what their doing, have the right equipment, and are far removed from competent medical care.

 

[ScubaFeenD]

I was not talking about in water decompression in my response. I was talking about omitted decompression stops. there is a big difference.

Omitted Decompression: I missed a stop for some reason or other and I have the ability to drop down immediately and do that stop. I have no symptoms of decompression sickness, and I am trying to keep it that way. It is the same preventative measure as a routine deco stop or safety stop.

In-water Decompression: I have surfaced, with or without missing any stops. I may have even completely removed all my gear. I begin to show definite signs of DCS. A decision is made to return me to the water to use the water pressure as a replacement for a recompression chamber.

The two are very different. I view the first as close to routine, and I view the second as a very serious matter that should only be attempted by people who know what their doing, have the right equipment, and are far removed from competent medical care.

Isnt it In-water Recompression?