Any downside to extending the safety stop?

[pickens_46929]

So I will add my $0.02 here... lots of people have hit on or focused on the DCS aspect of it.

I'll add "provided you can do the additional time comfortably"....

If you're cold, have a headache from perhaps C02 retention, feel tired, have to pee and forgot to hook up your pee valve, are just "done" with the dive or too hot (yes it can happen)... then you're not comfortable and you should do your safety stop and surface.

Don't feel you have to hang out longer just to see how much of your tank you can suck down.

Again, you can call the dive for any reason and anytime - even at 15 ft.

 

[KeithG]

Doing this on a live aboard can seriously impact your freshly baked chocolate chip cookie ration as all of the air hogs will already be on board bellying up to the food trough.

 

[Kevrumbo]

Assuming that you have no issue with getting low on gas, that you won't be separated from your buddy or dive group, and so forth, is there any disadvantage from a DCI perspective to extending the safety stop at 15 feet from 3 minutes to a longer period?

Will going from 3 minutes to 5 minutes or 8 minutes, say, make any meaningful reduction in residual nitrogen?

Thanks in advance.

Originally Posted by Mike Boswell
When we were diving the wrecks in Chuuk last year, our DM (Cindy) explained to us that we would be doing regular decompression stops on every dive - 3 minutes at 30 feet and 10 minutes at 15 feet, as an added safety precaution, even though our dives were within NDLs. I remember thinking this was being overly cautious: Boy, was I wrong!

For an interesting read about diving in exotic locations, see Alert Diver | Bent in Chuuk

I know this extra conservative profile is standard procedure for the recreational divers on the Truk liveaboard Thorfinn, and continues to be applied by Cindy and Rob -former Thorfinn Dive Guides- & now the managers at the Truk Stop Hotel dive-ops.

With regard to the wreck dives in Truk, you tend to load & saturate the slow tissues in general on repetitive dives over a week's time (note that the slow tissues are responsible for most type one DCS pain only events), so it's good practice to extend out that shallow "safety stop" on backgas Air, Eanx30 or 32. (A more efficient method is to extend that safety/deco stop at 6m by a switch off backgas to 100% Oxygen, but that requires Advanced Nitrox & Decompression Procedures certification, something way beyond the OP above).

 

[Adam Grose]

As long as you have enough air to STAY at the stop depth for 5 min.


Gcullen94 wrote: "There is NO disadvantage in adding time to a safety stop. I am having trouble finding it but DAN did a report that 5 minutes is a good time because it takes about 5 minutes for your blood to be circulated though your body, this causes much more offgasing than a 3 minute stop. I honestly don't see a reason however to extend a "safety stop" to 8 minutes. I commonly hang out at 20 for 2 and 10 for 3, with about a 30 second transition from 20-10 and 10 to surface. Above around 30 feet your body stops on gassing significant amounts of nitrogen."

 

[clownfishsydney]

Doing this on a live aboard can seriously impact your freshly baked chocolate chip cookie ration as all of the air hogs will already be on board bellying up to the food trough.

Not when everyone on the boat is doing the same. Our club chartered a whole boat in 2012 in Indonesia. Every single dive by every person had "safety stops" of at least 15 minutes. I do not think we did a single dive under 70 minutes apart from night dives which had a maximum limit of 60 minutes (for safety reasons).

In Australia the standard has been five minutes for at least the past 20 years as far as I remember. On my boat, you do less than five and you do not get invited back.

 

[bansiphansalkar]

Except that you collected a bit more Nitrogen in your system & may slightly affect you next dive NDL ..... Don't know of any other disadvantage.




Bansi

 

[miketsp]

Interesting that everyone focused on the physiological aspects. I agree that's the main issue on a daytime dive but most places where I go night diving the recommendation is to minimize the stop or eliminate it altogether and if you have to do a stop it's done with lights out to not attract sea life. This can vary from needle fish to much bigger and more aggressive species.

 

[AfterDark]

Except that you collected a bit more Nitrogen in your system & may slightly affect you next dive NDL ..... Don't know of any other disadvantage. Bansi

At 15FSW?? No effect, not even a little. The body is releasing nitrogen at that depth not absorbing it. I don't even take my PDC if I'm diving above 30FSW and I don't do a SS for a dive above 30FSW; the whole dive was a SS.

 

[Ricky B]

Interesting that everyone focused on the physiological aspects. I agree that's the main issue on a daytime dive but most places where I go night diving the recommendation is to minimize the stop or eliminate it altogether and if you have to do a stop it's done with lights out to not attract sea life. This can vary from needle fish to much bigger and more aggressive species.

As the original poster, I can say that my intent was indeed to ask about the physiological aspects. But what you don't think about is sometimes more important than what you do think about. So you made a good point about using a light on the safety stop on a night dive. I hadn't even considered the issue.

 

[faze]

Research in the US has shown that the type of safety stop has quite a significant impact on bubble presence and formation post dive. The optimum was found to be 1 min at 6 metres and 4 min at 3 metres.

Results were staggering in that this stop resulted in all bubbles being gone within 45 minutes and that upon surfacing, this group had less bubbles in their system than a group that did 2 mins at three metres had an hour later!

(Even more staggering was that the group that did no safety stop had more bubbles in their system after two hours than the initial group had upon surfacing!)

Dive profile was 30 metres for 25 mins.

Another interesting observation was that the slower tissue types are often still on gassing on your safety stop.

[source: Deco for Divers – Mark Powell]