Pony Tips

[Wallowa]

I also have no idea what a safety stop tank is - one option is a drop tank that is there for anyone on the safety stop that is low on gas. However that is not solo diving equipment.

A safety stop is simply a chance to off gas even if you don't need to. You most certainly do not need another tank in order to do so. There is as much gas as you can breathe just above your head.

Chrisch,

Not complicated....or so it seems to me....yes, safety stops are just that, to enhance the removal of nitrogen from tissues and blood with a stop in ascent; not required but beneficial....to further improve that removal of XS nitrogen you use higher %s of oxygen in the breathing gas at a safety stop to take advantage of the 'oxygen window'....as I dive air [21%] and within NDL, my safety stops are to assure that I have removed as much XS nitrogen as possible and reduced or eliminate as many microbubbles as possible before surfacing....extra critical because I often dive above 7,000 ft ABSL...I will be using EAN in the future on my safety stop and since I dive 21% I will need a small bottle of EAN for the safety stop.


As for other posts with vitriolic comments, none of us are the "smartest person in the room".....to each their own. Keep it civil and informative.

DSO

 

[LI-er]

yes, safety stops are just that, to enhance the removal of nitrogen from tissues and blood with a stop in ascent; not required but beneficial....to further improve that removal of XS nitrogen
DSO

Nobody in this thread was looking for an explanation of a safety stop, no clue why you went to the trouble of stating what is obvious to all certified divers, as it's something learned in the basic open water course.

 

[Wallowa]

Nobody in this thread was looking for an explanation of a safety stop, no clue why you went to the trouble of stating what is obvious to all certified divers, as it's something learned in the basic open water course.

I was responding to Chrisch's question of why I need a 'separate tank' [see his post] with EAN since I dive 21%.....I thought that post would have been obvious....obviously it was not obvious to you....no big deal, but why critic my post? Lets exchange information without sniping.

Using EAN on a safety stop if dive gas was 21% requires another tank with EAN at that stop or a second stage with EAN from a surface platform. My request was what % EAN [or 100% 02] folks on this forum were using at their safety stops. If basic scuba classes now address EAN at safety stops when diving air I missed that.

 

[inquis]

My request was what % EAN [or 100% 02] folks on this forum were using at their safety stops.

I'd guess every single diver on this forum is using their back-gas at their safety stop, so typically 36% or 32%. I believe you're substantially overthinking this, as the nitrogen off-gassing during a 5 minute safety stop after an NDL dive is hardly anything, even with the maximum possible gradient using O2 [ETA: which brings its own set of dangers].

You will gain much greater benefit from diving Nitrox during the entire dive (same bottom time as if you were on air). Not absorbing the gas in the first place is vastly smarter than a poor attempt to get rid of it in the final moments.

 

[Wallowa]

I'd guess every single diver on this forum is using their back-gas at their safety stop, so typically 36% or 32%. I believe you're substantially overthinking this, as the nitrogen off-gassing during a 5 minute safety stop after an NDL dive is hardly anything, even with the maximum possible gradient using O2.

You will gain much greater benefit from diving Nitrox during the entire dive (same bottom time as if you were on air). Not absorbing the gas in the first place is vastly smarter than a poor attempt to get rid of it in the final moments.

Thanks good input and appreciated. I am after any improved reduction of microbubbles/decompression stress; even if very small ['hardly anything'] I want, no need, such a reduction due to previous injuries, age, decades of deep dives and current dive profiles to NDL. Unlike others on this forum who use 36% or 32% 'back-gas' even though EAN certified and having dived it in 80s, I currently only dive 21%.

My dive depths preclude using EAN and getting an EAN fill where I live would involve a 9 hour drive. I have a compressor for 21% fills and no intent or ability to mix my own EAN.

Yes, I concur dive shallower, use EAN as primary/safety stop gas and give a buffer from NDL would be another way to accomplish bubble reduction and possibly elimination. But, other than backing off NDL the other options do not fit why and how I dive.

My proposal to use EAN at safety stop when diving 21% is not a new concept and has been recognized as benefit for a long time. But I do not say or recommend that anyone else do what I plan on doing. You have mentioned other means to accomplish my objective and I do appreciate that perspective and suggestions. Again, let each diver decide how they conduct their dives.

Will add a perspective. You mentioned using EAN on safety stop as a "poor attempt to get rid of it in the final moment"; I understand what you said and meant, but consider that any reduction of tissue or blood nitrogen gradient that is above Pp pressure at surface benefits the diver and reduces the chance of asymptomatic injury. The final moment, surfacing, is the crucial decompression moment.

Thanks again, exchange was helpful for me.

 

[rongoodman]

If I was going to the bother of slinging a separate bottle for the safety stop I’d just fill it with O2.

 

[Wallowa]

If I was going to the bother of slinging a separate bottle for the safety stop I’d just fill it with O2.

Good suggestion. What bottle/valve/reg do you suggest? Thanks....

 

[LI-er]

If basic scuba classes now address EAN at safety stops when diving air I missed that.

You didn't miss it. Scuba classes don't address breathing EAN out of a dedicated bottle at safety stops because the concept is absurd.

 

[Wallowa]

You didn't miss it. Scuba classes don't address breathing EAN out of a dedicated bottle at safety stops because the concept is ridiculous.

Come on please quit with the insults and bloviations.

 

[chrisch]

Come on please quit with the insults and bloviations.

I don't think anyone is trying to insult you, it is simply that the use of anything other than back gas on a safety stop is totally unheard of and upon examination seems pointless.

Your goal of reducing the risk of DCI is perfectly valid, however the effectiveness of a very short exposure to a much reduced nitrogen gas is much less that the inconvenience and stress of having to carry that gas and with it a seperate tank and regulator.

If you want to give it a go by all means do so. Firstly the seperate tank will work as a bailout, so you need to match the gas mixture to the maximum planned depth if you wish to gain that benefit. Pure O2 will be best for clearing nitrogen but is useless as a bailout unless the dive is very shallow. EAN 32 or similar is more intelligent but then as pointed out above is a better choice for the whole dive.

For a safety stop only perhaps the best option is a small self contained system like the Spare Air. Anything larger and it seems to me you are loading on more nitrogen by dragging the tank around than your are off gassing on the stop. Hence the pony option is probably counterproductive.