Deep Stops Recreational Divers

[Steelyeyes]

No, but it can be ignored.

On my G2 you can chose it as an option either way. It's just a 2 minute timer that's easily ignored.

 

[tcpip95]

I’ve only been diving recreational for 9 years. I have to admit that I didn’t understand the term “deep stop”. I took it to mean just doing decompression stops when coming back up from depth, but as I read this thread it sounds like something different; something that “once was, but no longer is”. So I’m not sure how to answer the poll question.

Wife and I each have dive computers. Whenever we go > 60’, the safety freak in me always has us doing at least a 3 minute stop at 20’ whether computer says to or not. Is that what’s meant by a deep stop? (BTW, usually never go greater than ~85’ when diving, and only once was >100’. In those cases we followed computer’s instructions for two stops at 45’ and 20’ IIRC).

 

[rsingler]

No, but it can be ignored.

Actually, PDIS in Uwatec computers can (and IMHO, should) be turned off.

 

[Bob DBF]

All scuba dives are decompression dives.

"No stop" is a much better term than NDL, IMHO.

I don't know how they teach it now, but I learned that No Decompression Limits was because there was no decompression stop or other restrictions (vertual overhead) on your direct ascent to the surface at any time in the dive. We did learn some rudimentary deco theory in case we got in a jam and wound up in deco for any part of a dive.

I think the real issue is that NDL is shortened to No Decompression diving by many. Add to that the amount of time "wasted" discussing deco theory in an OW class, including what NDL actually means. It a chicken and egg kind of question.



EDIT:
The actual term is No Dcompression Limits. This was borrowed from the US Navy back when recreational diving began.
My memory left off the s on limit, it bothered me so I looked it up.



Bob

 

[KenGordon]

I’ve only been diving recreational for 9 years. I have to admit that I didn’t understand the term “deep stop”. I took it to mean just doing decompression stops when coming back up from depth, but as I read this thread it sounds like something different; something that “once was, but no longer is”. So I’m not sure how to answer the poll question.

Wife and I each have dive computers. Whenever we go > 60’, the safety freak in me always has us doing at least a 3 minute stop at 20’ whether computer says to or not. Is that what’s meant by a deep stop? (BTW, usually never go greater than ~85’ when diving, and only once was >100’. In those cases we followed computer’s instructions for two stops at 45’ and 20’ IIRC).

You example going past 85ft and getting a stop at 45ft would be a deep stop. They were a fashionable idea based on some observations by a bloke collecting fish quite deep. Your stops at 20ft are where most non deep stops happen, although yours will be option safety stops rather compulsory decompression stops.

It is not clear cut though, your 45ft stop is deep for a 100ft dive, but probable not for a 200ft one.

 

[MargaritaMike]

When I did my ERD course, then later my Trimix cause. Deep stops where taught.
I habitually did a 'deep stop', but generally I planned my stop at 32m, my gas switch depth. I found that a planned stop at the gas switch depth was advantageous. In that it allowed me to settle, and switch gears to the ascent phase. It also allowed me to double check my ascent schedule (they where all hard written tables).

I still find it very relaxing at the end of the dive to stop 'early' as part of the ascent for a minute or so, make sure I'm on plan.

Even on CCR mixed gas course we effectively did a deep stop. This was because we flushed the loop, purging helium from the loop and filling with travel gas - i.e. a switch to Nitrox. The issue with CCR is that you are off gasing helium back into the loop during the decompression phase.

There was a great presentation at one of the BSAC Diving Officer Conferences about decompression theory, I think it was given by J M Imbert (A long time ago 15 years?). Which, from what I remember, showed, that extending the shallow stop was far more beneficial than extending the deep stop. i.e. for a like for like dive. Again, from what I remember, the deep stop reduced the risk of joint hits, but shallow stops reduced the risk of neurological hits.
The great shame is I don't think the material was ever published, or not so that I could study it.

Please read the title of the thread and the question for the poll: Deep Stops Recreational Divers
Do you conduct a deep stop when you are diving within the recreational limits; If so, at what depth?
What you described is not recreational diving. Yes, you may do it for recreation, but it is typically considered tech diving.
Again, just my 2 cents.
Cheers -

 

[KenGordon]

Actually, PDIS in Uwatec computers can (and IMHO, should) be turned off.

Since the tone of your post shrieks argument I thought I would join in by contradicting the SB love-in position

I find that the deep stops my HelO2 generates on an otherwise no-stop (aka recreational in PADI speak) dive are at depths like 17m or 11m and for one or two minutes. Deeper than that and the dive will probably involve real stops or it will have been a pointless bounce staying within no stop times.

This is quite different to the kind of deep stop introduced by VPM or GF. Those may start at similar depths but are then followed by stops every 3m (or 6 if you choose to stay down longer) which generally get longer at each depth. Thus a deep stop profile might add tens of minutes below the conventional 6 or 9m stop depths.

So, what is the impact of such a ‘recreational’ deep stop? That will depend on the exact profile, but since it is otherwise a no stop dive it is likely to off gas in the fastest couple of compartments and on gas in slow ones, ones in the middle we can’t tell. This is the same as happens in a 6m safety stop.

Fashion has swung against things called “deep stops” in other circumstances. Care should be taken in assuming that the arguments there apply to no stop dives. Worst way the extra risk is equivalent to a 4 minutes longer no stop shallow reef dive.

 

[AfterDark]

I've never read any hard evidence that deep stops are beneficial, only theory. So no deep stops for me.

 

[Gareth J]

Please read the title of the thread and the question for the poll: Deep Stops Recreational Divers
Do you conduct a deep stop when you are diving within the recreational limits; If so, at what depth?
What you described is not recreational diving. Yes, you may do it for recreation, but it is typically considered tech diving.
Again, just my 2 cents.
Cheers -

I would agree Trimix is 'technical diving'.
But other than that, I'm not sure if there is an answer. I use a CCR for 90% of my dives (2018 = 100%). So am I recreational or technical?
Most of my dives have a compulsory stop, not normally mine, but for my OC buddy. - with my agency, dives including compulsory decompression stops are recreational dives. As are dives with Nitrox, as are dives with accelerated decompression.

If you are doing dives where deep stops are planned or added by a dive computer, then is that still a recreational dive, or a technical dive?

My last set of coastal dives in 2018 where the Farne Islands, all shallow dives (less than 25m), my buddy was OC, we need stops at the end of each dive, is that recreational or technical? (The dives where too shallow for deep stops).

Different agencies have different definitions for recreational dives. About the only thing they all agree is the Trimix is technical. Deep stops where (are?) a technical diving tool.

Personally, I don't think I've done a technical dive in the last two years, because none of my dives have included trimix.

 

[Vitesse2l]

Agree with Gareth on this. What's is technical? A nitrox dive in low vis dealing with narcosis and an MOD in an overhead environment or a crystal clear tropical dive incurring a minute of deco?