Pony tanks Good or Bad? - POLL

[MikeFerrara]

If we're really going to discuss this, why don't some one submit an equipment configuration (the whole thing) and a dive plan explaining why they feel they need a pony bottle? Then we could discuss other possible options in relation to that dive.

 

[MikeFerrara]

Under the ice, solo diving is safer and far simpler than trying to manage 2 divers and 2 lines under the water at once. A pony provides additional saftey without the weight or bulk of doubles on what are normally relatively short and shallow dives.

I disagree. I ice dive with a buddy and my doubles or a single with an "H" valve. The leash to the surface probably creates the biggest possible use for a buddy.

For solo diving in general an Air 2 offers the same alternate access to the primary air supply if the primary second stage fails and does it without adding another hose or another conventional second stage to get in the way of or be confused with the second stage off a pony. A pony then provides a completely redundant system in case of a first stage failure. In situations where the volume of air provided by doubles is not required, a pony is a very valid option for a solo diver.

What kind of second stage failures are you seeing that don't result in a constant flow of gas. H-valve before air 2

 

[saintsfan]

I dont plan my dives around it but it sure is nice to know its there.I do a bad thing once in a while and dive solo, and that to me makes it invaluable that coupled with my 12 year old son getting certified as of the 18th(final dive).I still use an octo connected to my low pressure inflator hose so i dont have two alternates to secure.by the way when i do solo dive i usually come up in the 5-700 psi range. piece of mind!!!

 

[diver101]

I dont see how anyone could possibly think redundancy is not good. More air is better, period.

 

[DCDivenut]

Without getting into the debate of "bail out vs. allowance for bad technique"
one strike against pony bottles in the increased risk of entanglement. Has anyone looked at developing some sort of shroud/cover so that when a pony is mounted on a tank the connection is covered to lessen the risk?

Disclaimer... I have never dived with a pony and don't know that much about the various mounting systems... just asking...

 

[cornfed]

I dont see how anyone could possibly think redundancy is not good. More air is better, period.

You haven't been following the thread, have you?

 

[Uncle Pug]

I will try this one more time from a different angle.
~~~~
What would happen if you had an equipment problem? Lets say a blown o-ring which let all of your gas to escape. Would a pony bottle be a reasonable thing to have?

You are diving a single tank w/o a pony and have just arrived at your max depth of 120' and plan to work your way back up from there after a minute or two.

You hear bubbles and realize that your second stage to regulator o-ring has failed completely.

You signal to your buddy, point out the problem, call the dive and begin your ascent at 60fpm checking your SPG occassionally. You notice at 60' that you still have plenty of gas left in your 72 so you slow the ascent to 30fpm and make stops at 30', 20', and 10'. Then you make a slow ascent to the surface where you still have over 1000 psi.

Change scenario by adding pony.
Would you go to the pony? At what point?

Additionally:
Does the pony allow you to stay at 120' longer?
Does the pony allow you to go deeper?
Does the pony allow you to go over the NDL?
Does the pony allow you to stay at any point in the dive longer than your back gas would allow you to access the surface?

 

[Big-t-2538]

....why do we carry a octo?

Well....that would be for your buddy....since I reserve enough gas for my buddy and I to get to the surface on any dive I do, I am in essence his pony bottle. On the flip side of the coin...he does the same for me... In the event of some type of gas failure (reg, tank, inflator, etc.) from either of us, the dive is over and we know we can get back to the surface.

Now if you want to start to get deep (let's say beyond 100') and you actually want bottom time other than "went there, saw that" that would be the time we (I say we b/c I dive with my buddy) start looking at doubles.

 

[MikeS]

If we're really going to discuss this, why don't some one submit an equipment configuration (the whole thing) and a dive plan explaining why they feel they need a pony bottle? Then we could discuss other possible options in relation to that dive.

O.K. how's this?

Dive site U352, off-shore NC.
Max depth 115 feet.
Visibility expected 20-100 fsw.
Current expected none to slight.
Water Temperature expected 70 degrees

Equipment configuration:

TX-100 / TX-40 with long hose and bungeed backup
PS HP120 tank (3500 psi), 300 BAR DIN K-valve
Air Integrated Computer (Cobra)
SS BP&W with Pioneer 36 and ACB Weight system
2.5 mm full wetsuit

Bailout Bottle: Stage slung pony AL30 with DS4/TX40 and SPG

Dive Plan:

Descend following the anchor line to wreck and swim around the wreck.
Return to anchor line when first buddy down to 2300 psi (2/3) or at ½ NDL for 120 feet.
Surface, hopefully on the anchor line NLT when the first buddy hits 1200 psi
Ascent rate 30 FSW/min with 1 min stop at 50 fsw and 5 minute stop at 15 fsw.

Hypothetical Scenario 1: On the way back to the anchor line a lp hose bursts resulting in an explosion of bubbles and a rapid loss of back gas.

Option(s) without pony:
Locate buddy as alternate air source, attempt to return to anchor line but start direct ascent when down to 1200 psi.

Option(s) with pony:
Locate buddy as alternate air source, attempt to return to anchor line but start direct ascent when down to 1200 psi.
Switch to pony as alternate air source

Analysis Questions:

Is the rig complication as a result of adding the pony worth having an additional option in an OOA situation?

Is there a better configuration for obtaining the same or similar option?

 

[Genesis]

O.K. how's this?

Dive site U352, off-shore NC.
Max depth 115 feet.
Visibility expected 20-100 fsw.
Current expected none to slight.
Water Temperature expected 70 degrees

Equipment configuration:

TX-100 / TX-40 with long hose and bungeed backup
PS HP120 tank (3500 psi), 300 BAR DIN K-valve
Air Integrated Computer (Cobra)
SS BP&W with Pioneer 36 and ACB Weight system
2.5 mm full wetsuit

Bailout Bottle: Stage slung pony AL30 with DS4/TX40 and SPG

Dive Plan:

Descend following the anchor line to wreck and swim around the wreck.
Return to anchor line when first buddy down to 2300 psi (2/3) or at ½ NDL for 120 feet.
Surface, hopefully on the anchor line NLT when the first buddy hits 1200 psi
Ascent rate 30 FSW/min with 1 min stop at 50 fsw and 5 minute stop at 15 fsw.

Hypothetical Scenario 1: On the way back to the anchor line a lp hose bursts resulting in an explosion of bubbles and a rapid loss of back gas.

I would take the pony on such a dive, assuming no penetration.

If I intended to penetrate, I would take double LP72s.

In hypothetical situation #1 posited, if the LP hose blew I would breathe the backgas until it was exhausted, assuming it still worked at all, then switch to the pony. My buddy is my tertiary backup in this situation. I would prior to the dive compute my expected consumption so I would KNOW when I must bail from the bottom and make a free ascent (no line) in order to do my stops and reach the surface. My "stop protocol" for such a NST dive is 1 minute @ 70', then 1 minute from 50, 40, and 30', with at least 3 minutes @ 20-15 (my computer doesn't show me at "safety stop" below 19'), and then an approximate 3 minute ascent from 20' to the surface, which I time by ascending 1 foot every 10 seconds.

If I was doing that dive on doubles, I would first isolate (protecting half my remaining supply immediately, unless it was instantly obvious which post was the offender), then close the offending post and breathe off the remaining regulator. Again, my buddy is my tertiary backup in that situation.

In either situation I would know when my gas supply mandated an abort from the swim back to the ascent line, and would make a free ascent and shoot a bag once on my stops once that pressure was reached. This would cause the bag to appear close in behind the surface vessel (if not ahead of or abeam of it), which I would have told the captain meant that I was unable to return to the line and was making a free ascent.