Optimal Pony Bottle Size for Failure at 100ft?

[Pearlman]

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?

 

[OMyMyOHellYes]

No . . . but IMHO better repeated pauses -under control- than constantly looking at your computer's ascent rate indicator all the way up from 130'/39m, making sure it reads no more than 30fpm (better to just stop and hold for 10 seconds, and then move up taking 10 seconds to ascend 10'/3m -->essentially again, an overall rate of 30fpm/9mpm. . .

It has been reported that you can just follow the bubbles...

That requires no reference to a computer or depth gauge+watch. Still see no need to stop along the way.

 

[lowwall]

It has been reported that you can just follow the bubbles...

The little bubbles.

 

[Nick_Radov]

Staring exclusively/continuously/obliviously with no situational awareness -at your computer's ascent rate indicator in currents, poor visibility, low ambient light/night dive, and a high density kelp forest canopy (throw in some monofilament fishing line too) like we can have here at SoCal offshore divesites at Catalina/Channel Islands National Park? (Or Poor Knights Islands where you are?)

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.

 

[rsingler]

Will let me play mediator here...
@SpaceX Aquanaut, by his profile, is a very experienced technical diver. So I think some of the criticisms here may be a little over the top.

I found myself in similar circumstances a decade ago, where I took a position and felt the need to defend it.

If one accepts the possibility that SpaceX dives to significant depth off surge'y oil platforms, then SMB's that might get entangled might not be a good choice. But similarly, that same surge might want to keep someone a bit further away from the legs to avoid getting barnacle rash. So visual indicators may be lacking, especially at night.

My own conclusion is that the technique described is a bit of Normalization of Deviance, where a solution that seemed logical in the circumstances, and works most of the time, gradually deviates further and further from "standard" practice.

I think it ran up against a wall when the constraints of a limited pony supply were imposed. Things were exacerbated by an erroneous computation that ended up being 10 fpm ascent rate instead of 30 fpm.

If his average is 30fpm on a no-stop dive, then I have no argument with it, and an AL19 or AL40 will work. But me, I have no problem with maintaining a fairly stable ascent rate with occasional glances at my computer.

Tomaytoe, tomahto.

 

[Nick_Radov]

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?

No, that sounds overly complex and unlikely to work in a real dive when you're task loaded and managing an equipment failure. By all means practice your buoyancy control and ascent skills. And be mindful of your breathing. But there's no point in trying to link a particular breathing rate to a target ascent rate. Don't tie yourself in knots trying to over think the basics.

 

[rongoodman]

Does that sound reasonable to you folks?

It sounds way too complicated to me.

 

[Celt]

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?

You could practice using your exhaust, you can’t use the crown as it’s creating an upward flow. Use single bubbles below the crown between 2.5 and 5mm. 2.5mm is rising at about 30fpm and 5mm about 45fpm. I used to keep pace between the crown and these bubbles at approximately 60fpm now I stick with the smaller bubbles. In an emergency I’d travel with the crown but don’t do that it’s dodgy.
P.S I’m talking about salt water

 

[lowwall]

Use single bubbles below the crown between 2.5 and 5mm. 2.5mm is rising at about 30fpm and 5mm about 45fpm.

Don't forget your calipers!

Seriously though, this is good advice. Follow the little bubbles with an occasional check of your computer to make sure you are on track.