Alert diver article on Deep Stops

[Sloth]

For the experienced diver it is a big worry. Most of the other factors are uncontrollable or unknowable. Maybe I WILL totally panic underwater, but I try to prepare myself to prevent it.

I've seen a lot of people get bent and a few get permanently disabled. When you see that and maybe been bent yourself a few times, this crap becomes a big deal. It is for the most part preventable and when it does occur it is very important to have oxygen available. To say that it is so unlikely that it is unimportant is unwise. The risk is not that high, but the consequences are too severe to ignore.

A recreational diver would be better severed working on in water comfort and buoyancy control to insure they don't have an in water accident and not sweating over whether deep stops or what computer computes the safest schedule in order to avoid DCS.

Were all the people you've seen with serious DCS hits diving recreational or are you talking about tech diving?

The only DCS hit I've ever seen a recreational diver have was from an inner hit assumed to be caused by PFO.

 

[dumpsterDiver]

Actually the bad bends I have seen were both recreational, no deco dives. One guy might also have had a stroke, but the other guy swears he didn't do anything wrong or different and he had thousands of dives.

A recreational diver should know how to control buoyancy and should not need to be "working on it". Practicing in water comfort does NOT ensure that an accident will not occur; where do you come up with this stuff?

 

[Sloth]

A recreational diver should know how to control buoyancy and should not need to be "working on it".

We may have a different definition of buoyancy control but probably not. The majority of tourist divers I saw while living in Hawaii had virtually no buoyancy control. So sad :depressed:

 

[deepstops]

Deepstops been very very good to me (I feel better no matter what the profile is).

 

[halocline]

I think part of the issue raised in the article was that simply adding a deep stop onto all recreational NDL dives is probably too broad a recommendation. A couple of the panelists said something about the need to design computer models that incorporated deep stops in a way (meaning in specific dive profiles) where they would be most effective.

Comparing two identical profiles, one with a deep stop and one without, means that the time spent at the deep stop will either come out of bottom time, or adds a minute to the entire profile. Either way it's hard to know if benefits derived from this practice would be due to the deep stop or to the added minute of decompression. (At least that's what one of the panelists seemed to be implying) I suspect a "fairer" comparison would be to have one profile include a one minute deep stop and three minute safety stop, while the other includes no deep stop and a four minute safety stop. That way the profiles could be otherwise identical, including total bottom time and total dive time.

It is an interesting topic.

 

[ROMO DIVER]

First of all I think that the argument that there is "nothing to back it" should be taken with a grain of salt. People swore that the earth was flat not too long ago due simply to the fact that no one had "proven" otherwise. As for "evidence based medicine" this is one of the biggest problems with healthcare today. If we only do what has been done before and never allow any deviation we will never fully address any medical situation.

The previous posts concerning the ongassing/offgassing of fast vs. slow tissues benefiting from deep stops are right on. One thing I have not read but believe is worth mentioning is the rate of change in pressure gradients during ascent. The pressure gradient change is what dictates the amount of nitrogen that can be offgassed and not the rate of ascent. You can ascend faster at deeper depths and slower as you get shallower and still offgass at the same rate. If you were to incorporate deep stops into an alogarithm I think that it should be dictated by pressure gradient change and not strictly by depth.

 

[diverrex]

Did anybody else notice in the same edition in the article on diving at the Flower Garden Banks National Marine Santuary the sidebar states: "Liveaboard crews caution divers to make slow ascents, a one minute saftey stop at half their maximum depth and a three-to five-minute stop at 15 feet."

And also in the same edition the Dan Was There For Me feature by Eric Hanauer about getting bent in Baja on his dive to 120 without having exceeded NDL where he details his ascent as "... we started slowly up the anchor line, hand over hand. A one-minute safety stop at 60 feet was followed by another hand-over-hand ascent to 20 feet, where we made a three-minute safety stop."

Ironic.

 

[Sloth]

Did anybody else notice in the same edition in the article on diving at the Flower Garden Banks National Marine Santuary the sidebar states: "Liveaboard crews caution divers to make slow ascents, a one minute saftey stop at half their maximum depth and a three-to five-minute stop at 15 feet."

And also in the same edition the Dan Was There For Me feature by Eric Hanauer about getting bent in Baja on his dive to 120 without having exceeded NDL where he details his ascent as "... we started slowly up the anchor line, hand over hand. A one-minute safety stop at 60 feet was followed by another hand-over-hand ascent to 20 feet, where we made a three-minute safety stop."

Ironic.

In the "DAN was there for me" was no NDL mean the dive ended at the beginning of ascent and at that point he was NDL or did he have a computer that showed it as a clean dive?

Just as in deco dives if you dont get off the bottom fast enough you will accrue more nitrogen loading then you've accounted for.

If slowly up the anchor lines means 10ft per min from 120 then yeah that has nothing to do with deep stops. If hand over hand means slowly off the bottom then his issues started at depth not during his deep stop.

 

[diverrex]

In the "DAN was there for me" was no NDL mean the dive ended at the beginning of ascent and at that point he was NDL or did he have a computer that showed it as a clean dive?

Just as in deco dives if you dont get off the bottom fast enough you will accrue more nitrogen loading then you've accounted for.

If slowly up the anchor lines means 10ft per min from 120 then yeah that has nothing to do with deep stops. If hand over hand means slowly off the bottom then his issues started at depth not during his deep stop.

The article is not clear. It does say "...when our computers showed we were nearing no-decompression limits, we started slowly up the anchor line, hand over hand....Both of our computers had cleared well before we reached 30 feet."

To me that might read that he was close to but not at NDL just before ascent but since he mentions "cleared well before we reached 30 feet" that may mean he hit NDL sometime during the slow ascent.


The main point of his experience is he and his wife did identical dives, he was bent, his wife not. He either never hit NDL or at least cleared prior to a safety stop. He did a slow ascent, deep stop and safety stop, with a computer showing he was clear but still became bent. DCS is not completely predictable and affects people differently. He does say "we were nearing no-decompression" so they clearly pushed close. He ends the article by saying his deep diving days are over and he is diving more conservative now. A good practice to follow for an unpredictable issue.

 

[Blackwood]

The article is not clear. It does say "...when our computers showed we were nearing no-decompression limits, we started slowly up the anchor line, hand over hand....Both of our computers had cleared well before we reached 30 feet."

To me that might read that he was close to but not at NDL just before ascent but since he mentions "cleared well before we reached 30 feet" that may mean he hit NDL sometime during the slow ascent.


The main point of his experience is he and his wife did identical dives, he was bent, his wife not. He either never hit NDL or at least cleared prior to a safety stop. He did a slow ascent, deep stop and safety stop, with a computer showing he was clear but still became bent. DCS is not completely predictable and affects people differently. He does say "we were nearing no-decompression" so they clearly pushed close. He ends the article by saying his deep diving days are over and he is diving more conservative now. A good practice to follow for an unpredictable issue.

He also had a wicked hit that took multiple chamber rides and later therapy to treat.

I don't suspect that his problems stemmed from that single profile. That just happened to be his most recent dive, so it's the one he's talking about. I seems likely that the dive in question was simply the straw that broke the camel's back.