'deep stop' experiences

[Wibble]

Fatigue after a dive could have numerous implications. Perhaps you weren’t using Nitrox. Perhaps you weren’t hydrated the night before? Perhaps your fitness level is wanting? If you have accidentally exceeded the No Decompression Limit while at 100 ft, you may want to consider deco ratio on the fly (risk mitigated) by ascending to 40 ft and remain there for 3-minutes, then ascend to 30 ft and remain there for 3-minutes, then complete your Safety Stop for 3-minutes at 16 ft. Discontinue diving for 3-hours minimum.

As ever there’s a slither of truth but wrapped in a mess of words.

For other divers, follow the planning you were taught. If that training included "deep stops" then it’s time to get an update as things have moved on.

The one empirical factor seems to be a slow ascent for the last 6m/20ft, at least for decompression dives.

 

[kaylee_ann]

Obedience to authority is not a moral necessity. To even remotely suggest something like this is based on years of experience. Make observation of PADI DSAT tables.

it's not obeying authority. more like listening and learning from those much more knowledgable about certain topics than we are.

 

[Alaskan Scuba Dude]

That’s a lot to remember, can I just follow my computer or should I put your post on a piece of parchment and bring it with me whenever I go diving?

I’m certain there are many on this forum that could have a cordial conversation with a tombstone. Long before I knew about George Jujitsu’s Ratio Deco on the fly, we were compromising our extended No Decompression Limits by stopping at 12 meters for a few minutes before ascending to 9 meters then to 6 meters to clear the Nitrogen bubbles. It’s apparent that ScubaBoard’s resident John Atlas was so immersed in carrying the Scuba world on his shoulders that he hadn’t seen the correlation between Buhlmann and DSAT algorithms for recreational divers. Anyone who has accidentally exceeded their NDL knows that the recreational dive computer becomes temporarily invalid. The other solution is to off-gas on O2, once onboard the boat, and that isn’t going to happen unless you bring your own gas.

 

[Soeren]

After the DAN report from 2020 - where 58% of 40.000 known cases of DCS are dived inside the tables !!! - Deep Stop has bee an huge discussion.
As far as I see the problem with som computers, then Deep Stop is: "Bottom Time" not included in the calculation - and therefore it becomes an unproven extension of the "Bottom Time", because some slow tissue types still absorbs nitrogen on a Deep Stop. This according to the information I have been able to find. Deep Stop as far as I can find is based on an "not proven feeling" that became a sales parameters for new computers back in the days.
I have therefore chosen to turn off this function and now use the new updated algorithms that came in 2020 also e.g. Suunto Fused™ RGBM 2.
If anyone has knowledge that anything else is proof, I would very much like a link to the articles. Thanks.

 

[beester]

Since we are talking about "experiences" and not scientific data I think I (and everybody else) can chime in. The data from the last decade suggests that the deep stops practiced before did not provide the safety cushion that was communicated at that time and used by several models (RGBM and VPM, but also Buhlmann adjusted with GF's).

My technical dive data is not very big. I've done about 200 tx dives and about another 100 deeper dives before I dived tx on air. Range until 110m depth and exposures up to 4 hours of deco. Most of the deeper, longer exposure dives have been with GUE, using the "standard" 20/85 GF. That means that from a dive at let's say 90m you start your deep/deco stops at 60m more or less, so very deep.

I've never had a hit on any deep dives, using above method. However the data is of course limited (just 20 dives in the 90m range), so I could be just lucky.

Most technical diving I've done is in the 45-70m range with typical exposures of max 100 min. (so 1 hour of deco). In this range I've used above gradient but also more conservative ones on deepstop level (GF 50/70), both with success without any side effects that I know of.

Shallower but longer exposure (30-45m depth) I'll significantly increase conservatism and also reduce deepstops. Going even to a 50/60. The focus not being on the deepstops ( a 20/x vs a 50/x will only change the deco profile from first stop at 18m to 15m) but on longer deco at shallow depths. I'm quite afraid of slow tissues and have seen some nasty hits on relatively shallow but longer dives.

Luckily I haven't had a hit myself. Which is strange because I'm a reasonably fat **** (although I do run a lot).

Just came back from a week of diving (and will go on another expedition in 3 weeks). All diving the JJ rebreather in 50-75m range dives with bottom times up to 50 min and exposures up to 2 hours... running them on 50/70 because my buddy asked.

So all in all... I can't say a lot, so far (touch of wood) both methods (deepstops or not/less) work for me.

 

[EFX]

Anyone who has accidentally exceeded their NDL knows that the recreational dive computer becomes temporarily invalid.

It does? Invalid for what?

 

[Centrals]

Anyone who has accidentally exceeded their NDL knows that the recreational dive computer becomes temporarily invalid. The other solution is to off-gas on O2, once onboard the boat, and that isn’t going to happen unless you bring your own gas.

This is absolutely BS.
AFAIK all computers are capable to calculate simple decompression obligation. My 25yrs old Uwatec Aladin certainly would have no issue with that.
Most dive boat, if not all, that I have been on has supply of O2 for emergency use.

There is NO need to bring O2 on board.
You are just FULL of non-sense.

 

[boulderjohn]

It’s apparent that ScubaBoard’s resident John Atlas was so immersed in carrying the Scuba world on his shoulders that he hadn’t seen the correlation between Buhlmann and DSAT algorithms for recreational divers.

I assume you are talking about me, but I haven't the faintest idea what you are talking about here.

 

[boulderjohn]

Long before I knew about George Jujitsu’s Ratio Deco on the fly, we were compromising our extended No Decompression Limits by stopping at 12 meters for a few minutes before ascending to 9 meters then to 6 meters to clear the Nitrogen bubbles.

I am trying to cut through this gibberish, but I don't know what "compromising our No Decompression Limits" means. I also don't see how this relates to Ratio Deco, which is not even used on NDL dives. It is similar to Min Deco procedures, but that is not what that is all about either.

 

[boulderjohn]

Anyone who has accidentally exceeded their NDL knows that the recreational dive computer becomes temporarily invalid.

And finally, as others have already pointed out, all computers made in the last quarter century can provide decompression guidance to divers who accidentally exceed their NDLs.