Just bought a pony system, need help with answers...

[MikeS]

Karl_in_Calif once bubbled...
RMV 0.75

This seams a bit light to me. While my average relaxed SAC is just over 0.6 cfm, I suspect a situation that requires I switch to my pony will increase task loading and be somewhat stressful increasing the SAC rate. I have found this to be true when practicing in the quarry. Therefore I use 1.2 cfm as a realistic estimate.

Karl_in_Calif once bubbled...

from 185 ft --100 ft = 100 ft / min
from 100 ft -- 60 ft = 60 ft / min
from 60 ft -- 20 ft = 30 ft / min
from 20 ft -- 0 ft = full final usage of tank/bottle

This also seems a bit odd. I have never heard of changing the ascent rate based on depth. While in a way it makes sense since the percentage of change in pressure is less per foot at depth, it seems like a lot of task loading. I think I’ll stick with 30 ft/min.

Karl_in_Calif once bubbled...
I have also often heard the [fallacious] argument that "you need more time to sort things out" etc. In reality, when you switch to your pony, for whatever reason, its time to make like a hockey team and move the puck out of there.

I have to disagree with you here. The reason I carry a pony is for a backup in case of equipment failure. At the very least, after switching to the pony, I’m going to apply the breath, think, breath, think, philosophy. I want to ensure my breathing is under control, assess the situation and decide on an appropriate course of action before starting up. Then there’s my buddy; I want to make sure they understand the situation and what my course of action is. And of course depending on the situation I might swim to an anchor line or float a surface marker. All of these things take some amount of depth. While practicing in the quarry I found a time frame of between a half to a full minute to communicate with my buddy and float a surface marker realistic.

Mike

 

[MechDiver]

Karl_in_Calif once bubbled...


Actually those are standard current TDI protocols.

Your point? That doesn't make 100'/min less stupid at that depth.

MD

 

[cornfed]

Karl_in_Calif once bubbled...

fal·la·cious [ fə láyshəss ]

adjective

1. containing mistaken belief: containing or involving a mistaken belief or idea

2. deceptive: deceptive or liable to mislead people

[Early 16th century. Via Old French fallacieux from Latin fallaciosus , from fallacia (see fallacy).]

fal·la·cious·ly adverb
fal·la·cious·ness noun

Welcome back... any particular reason you felt it was necessary to include this?

 

[Karl_in_Calif]

MikeS once bubbled...
The reason I carry a pony is for a backup in case of equipment failure. At the very least, after switching to the pony, I’m going to apply the breath, think, breath, think, philosophy. I want to ensure my breathing is under control, assess the situation and decide on an appropriate course of action before starting up.

I agree with stop/breathe/think/act for entanglements, or for anything else EXCEPT gas supply failure.

You can easily do your thinking about what you will do in the event of a gas supply failure by thinking in advance, and establishing a protocol.

1) switch to pony, for whatever reason.
2) time to go home, now, not later, now.
3) if your buddy doesnt see you switching to your pony, and beginning your ascent, this is a separate problem, for another day.

 

[Karl_in_Calif]

MechDiver once bubbled...


Your point? That doesn't make 100'/min less stupid at that depth.

MD

Separate issue, comparision of agency protocols and standards.

I am sure Gilliam would stick to his guns. He is not here to argue with you however.

 

[cornfed]

MechDiver once bubbled...
Your point? That doesn't make 100'/min less stupid at that depth.

Mech,

Correct me if I'm wrong, but aren't ascent rates intended to limit pressure changes and hence off gassing rates?

If you play around with the numbers Karl gave, the rate of pressure change is insane! Those ascent rates are way outside the limits of any table or model that I've heard of.

 

[MechDiver]

cornfed once bubbled...


Mech,

Correct me if I'm wrong, but aren't ascent rates intended to limit pressure changes and hence off gassing rates?

If you play around with the numbers Karl gave, the rate of pressure change is insane! Those ascent rates are way outside the limits of any table or model that I've heard of.

IMO you're correct on both counts. Ascent rates may well vary with depth with no problems that I'm aware of. I.E. you can ascend more quickly from 200 ft to 100 ft than from 100' to 60', deco obligations/profiles/personal preference taken into account of course. Essentially, slow is good, particularly when in the offgassing depths.

Also, as 185' is He territory for alot of us, fast ascents are worse than for air. Either way, ascent rates that fast are stupid. As far as Gilliam is concerned, He's the "beer for lunch while diving" guy right?
Not sure what else needs to be said there.

MD

 

[Karl_in_Calif]

MechDiver once bubbled...

As far as Gilliam is concerned, He's the "beer for lunch while diving" guy right?
Not sure what else needs to be said there.

MD

Harrr matey! So run up your own pirate flag, and lets see under whose colors you sail!

Thats what it boils down to.

And pass the beer, I mean, pass the ice water please!

 

[MechDiver]

Karl_in_Calif once bubbled...


Separate issue, comparision of agency protocols and standards.

Ya know, I've read some things here you've posted that I thought were quite good and made sense. Then, you come out with stuff like the 100'/min ascent nonsense. Sad to say, that level of, ahem, "knowledge" appears to be more the norm.

Do you happen to drink more coffee sometimes? Maybe have something different to eat? Play with electric cords?? Watch Star Trek too much?
Just curious

 

[Karl_in_Calif]

MechDiver once bubbled...

Do you happen to drink more coffee sometimes?

Just ice water. Or fruit drinks, like apple juice or OJ. But definitely not OJ before diving; too acidic.

Caffiene is out of the question, for any kind of technical diving, and not a good idea, for NDL diving as well.