Optimal Pony Bottle Size for Failure at 100ft?

[johndiver999]

I am yet to perfect my ascent skills to the level of a tech diver (or do any tech course for that matter) but an idea just occurred to me which I think I will practice on my next dive vacation. Assume 3 sec for inhalation + 3 sec for exhalation with a 1 sec pause interval between each inhalation and exhalation. Then, one will be beginning the next inhalation at t+10 sec each time. So at every alternate inhalation breath, one should be at a -1mtr mark and not exceed it. Therefore on every 3rd inhalation one could glance at the computer to ensure no more than -3mtrs of ascent giving me two breath cycles to look around for situational awareness then enforce a one breath or 10 sec stop if one appears to be exceeding the ascent rate. Maybe switch from 40-80% lung breathing to 20-50% lung breathing depending on estimate of ascent, assuming one is correctly weighted.

Does that sound reasonable to you folks?

Nope, too much task loading and you are voluntarily introducing multiple stressors (or at a minimum complexities) where none is needed. Just come up slow, watch the computer, watch particles in the water, watch tiny bubbles, breathe slowly and efficiently.

If ascending in a very controlled manner is challenging for you, then the last thing you need is to artificially change your breathing.

I often deploy an smb at 30-40 feet, and even though I have had a ton of practice, I will still quite often, get distracted and sink several feet, maybe even 10 as I get it unclipped from my harness and rigged and then released. It is frustrating and embarrassing - even if there are no witnesses. This is a solo, open water ascent with no reference, so that might put things in perspective, but it is not an excuse.

Apparently I am so worried about floating up (while fiddling with the smb) that I subconsciously alter my lung volume and begin to sink - when that is not my desire. Sinking a little and resuming the ascent, is certainly more desirable than floating up too fast and losing control, but it is still not desirable.

So when I say, "trying to do some convoluted breathing pattern and counting etc. - does not sound like a good strategy, I am speaking from my own challenges.

 

[johndiver999]

You're not making any sense here. If you're out in open ocean (regardless of currents or visibility) then you need some kind of ascent line. So you're either going to be coming up the anchor line or sending up a marker buoy or staying within sight of the structure (like an oil rig or whatever). Use that to control your ascent speed while maintaining situational awareness and occasionally glance at your depth gauge. This is simple and easy.

High density kelp forest canopy doesn't exist at 130ft/39m deep dive sites. Giant kelp (Macrocystis pyrifera) only grows down to about 100ft/30m and only reaches high density (like a solid surface canopy) down to about 60ft/18m. If you're in a kelp forest then you can use a convenient stalk as a natural ascent line. No problem.

Frankly based on your comments I think you're unclear on the basics and are literally in over your head. Let me suggest that take a pause on any deep diving and seek out additional training in dive planning and failure management before you hurt yourself.

I make open water ascents from the bottom to 30 feet or so, with no visual (or physical) guideline - many dozens of times each year. I pretty much NEVER have a guideline.

Are you really suggesting that all ascents, even emergency ones, need to be aided by some type of visual or physical guideline?

I'm a little confused, because you normally make sense (in a somewhat overly conservative manner), but this seems to be way off base?

 

[Nick_Radov]

I make open water ascents from the bottom to 30 feet or so, with no visual (or physical) guideline - many dozens of times each year. I pretty much NEVER have a guideline.

Are you really suggesting that all ascents, even emergency ones, need to be aided by some type of visual or physical guideline?

I'm a little confused, because you normally make sense (in a somewhat overly conservative manner), but this seems to be way off base?

I was responding to a comment about dives to 130ft/39m out in the open ocean. Not 30ft dives from shore or in protected areas.

In a dire emergency during a recreational dive then go straight to the surface however you can. But a lot of divers including some "tech" divers struggle with making a controlled free ascent from 130ft with no visual reference regardless of tricks with little bubbles or whatever. Some of them ascend way too fast at first, then dump too much gas and sink again, rinse and repeat. I've seen it happen. And once they finally reach the surface they might end up out of sight of the boat, or get run over by another boat. Hence the importance of having something to use as a visual guide or handhold if at all possible.

The trouble with trying to explain this stuff online is if you post a clear, concise statement then some readers miss the previous context and try to pick it apart to find exceptions where it doesn't apply. Or if you pedantically restate all of the context in every comment to avoid any possible misinterpretation then readers get lost in the minutiae and miss the key points. Can't win, I guess. (Not criticizing you specifically, it just gets a little frustrating.)

 

[scubadada]

With experience, I have come to recognize my ascent rate, whether that uses bubble rise, I'm not really sure, I think not. This does not seem to be dependent on landmarks. My usual, leisurely, horizontal ascent rate is almost always about 20 ft/min. 30 ft/min seems fast. 60 ft/min seems very, very fast. I never look at my ascent rate and only check my depth when getting close to the safety stop, or a deco stop. It's interesting watching other divers with their eyes fixed on their computers, they generally end up somewhere near my depth. If I was to need to use my pony for an ascent, I'm pretty sure I could do it with a reasonable ascent.

 

[Diver-Drex]

Of course you can ascend without a reference. But there are several reasons for shooting a bag for an up line. Taking a minute to send one up aids your ascent rate, let’s the surface know where you are, helps prevent vertigo…

If you are prepared - training, planning and equipment, switching to contingent air and surfacing in a controlled manner should not be an emergency. Handling situations in a deliberate, thought out in advance and rehearsed manner results in better and more consistent results than panic.

 

[scubadada]

Of course you can ascend without a reference. But there are several reasons for shooting a bag for an up line. Taking a minute to send one up aids your ascent rate, let’s the surface know where you are, helps prevent vertigo…

If you are prepared - training, planning and equipment, switching to contingent air and surfacing in a controlled manner should not be an emergency. Handling situations in a deliberate, thought out in advance and rehearsed manner results in better and more consistent results than panic.

Of course, I often send up an SMB when I am solo diving in Palm Beach.

 

[johndiver999]

I was responding to a comment about dives to 130ft/39m out in the open ocean. Not 30ft dives from shore or in protected areas.

In a dire emergency during a recreational dive then go straight to the surface however you can. But a lot of divers including some "tech" divers struggle with making a controlled free ascent from 130ft with no visual reference regardless of tricks with little bubbles or whatever. Some of them ascend way too fast at first, then dump too much gas and sink again, rinse and repeat. I've seen it happen. And once they finally reach the surface they might end up out of sight of the boat, or get run over by another boat. Hence the importance of having something to use as a visual guide or handhold if at all possible.

The trouble with trying to explain this stuff online is if you post a clear, concise statement then some readers miss the previous context and try to pick it apart to find exceptions where it doesn't apply. Or if you pedantically restate all of the context in every comment to avoid any possible misinterpretation then readers get lost in the minutiae and miss the key points. Can't win, I guess. (Not criticizing you specifically, it just gets a little frustrating.)

thanks, I generally make open water ascents with no reference lines from 130 feet a few times each week. The reference to 30 feet is the depth where I often deploy an smb, to hang under.

I agree that shooting an smb from depth has its advantages, but in a dire emergency and when coming up on a pony, it is probably better to concentrate on ascending rather than futzing with a marker at depth. Doing it from a safety stop depth, makes a lot more sense to me - in a gas limited emergency.

I believe you that some tech divers can not make a decent ascent without a guide, but that is a skills problem not a gear problem. In my mind, anyone diving 100 feet should be able to ascend from 100 feet safely without any aids. I do admit it is tougher at night.

But.. if people really think they need to shoot an smb from depth in an emergency, then it definitely does make sense to carry a bunch more redundant gas.

 

[Tassie_Rohan]

I’m a big fan of a variable accent rate.

Rather than watch computer ascent warnings, which always seem to be too sensitive/noisy, I follow a simple ‘half depth’ formula:

I aim to be at half my current depth in 1-2 minutes time.

i.e. if I am at 40 m at 20 minutes into the dive, then aim to be at:

• 20 m at 22 min (10-20 m/min ascent rate),
• 10 m at 23 min (10 m/min),
• 5 m at 24 min (5 m/min)
• 3 m at 25 min (2.5 m/min)

(then 1.5m at 26min, 0.75m at 27, 0.37m at 28, 0.18m at 29, 0.09m at 30, 0.04m at 31, 0.02m at 32, 0.01m at 33, 0.005m at 34, 0.0025m at 35, etc… )

As my computer doesn’t display how many seconds are remaining in the current minute I round the first time/depth to the next minute. Sometimes I allow 2 minutes per ½ depth if feeling conservative/slow/lazy.

I find this really easy and simple to follow and it provides guidance on a variable ascent rate in line with current thoughts on deco: Many divers ascend too slowly at depth, and too quickly in the shallows.

Oh - and to answer the OP's question: following my formula you will need to carry an infinite amount of air to approach a surface you will never reach. Glad to be of help.

Cheers
Rohan.

 

[lowwall]

(then 1.5m at 26min, 0.75m at 27, 0.37m at 28, 0.18m at 29, 0.09m at 30, 0.04m at 31, 0.02m at 32, 0.01m at 33, 0.005m at 34, 0.0025m at 35, etc… )

Alert your nearest philosophy department if you ever manage to surface.

Zeno's Dichotomy Paradox

 

[-JD-]

Oh - and to answer the OP's question: following my formula you will need to carry an infinite amount of air to approach a surface you will never reach. Glad to be of help.

Not really. One heck of a lot of air, yes, but not infinite. Death from old age will kick in at some point.