Pony Bottle / Stage Bottle / Decompression Bottle. What's the difference?

[johndiver999]

Sorry, I do not understand what your point is. The purpose of carrying the pony is if you lose your gas supply. A 13 will barely suffice, if all goes well. That 13 is not for someone else, it is for me. Yes, you can give it to an OOG diver, but then you have no backup if you lose your gas, or the dip tube clogs, or whatever. So are you saying that if I leave the bottom with 1000, I can be at the surface with 500? But if someone is OOG, I must leave the bottom at 1500 so we each have 500? Or are you saying that you'll use that last 500 to get the OOG diver to the surface and get back on the boat with zero? Or what?

The scenario you describe above involves two simultaneous failures/problems. The buddy looses all gas supply and then the donor with the pony bottle ALSO has a total failure of a scuba unit.

It is my understanding that in recreational diving, we generally will assume ONE failure in a buddy team - and then implement a plan to get the team to the surface. For example, a buddy team without a pony will be in trouble if BOTH divers loose their gas supply. So this simultaneous failure is outside of the recreational emergency planning scenarios that I am familiar with.

If we are talking about recreational diving, I think we need to be somewhat consistent in our assumptions.

Also the statement (by others?) that a 13 cu-ft tank will require a super fast ascent from recreational depth is clearly incorrect. The math proves that point. The assumption that a diver would need to swim horizontally to acquire an ascent line/anchor line and also perform a safety stop seems rather extreme. Recreational divers are assumed to go directly to the surface when an emergency occurs. If that option is not available (in an emergency) then the diving activity should probably not be considered recreational.

It is unclear to me why some people want to diverge from recreational assumptions, when the scenarios involve recreational diving?

 

[tbone1004]

The assumption that a diver would need to swim horizontally to acquire an ascent line/anchor line and also perform a safety stop seems rather extreme. Recreational divers are assumed to go directly to the surface when an emergency occurs. If that option is not available (in an emergency) then the diving activity should probably not be considered recreational.

It is unclear to me why some people want to diverge from recreational assumptions, when the scenarios involve recreational diving?

wreck diving in current. Common in recreational diving up in this neck of the woods. U352 is a good example. 110ft to the sand, wreck is 218ft long. If the boat is tied into the bow, and you have an issue at the stern and you try to make a direct ascent, you're going to quickly find out how effective your DSMB or PLB is. Fairly strong current, 3atm's to ascent, and if things aren't in your favor, the wreck could easily be a quarter mile away from where you pop up. On the safety stop and the need to plan for it. Depending on how long it takes you to get everything stabilized and start moving, combined with generally slower travel speeds when in a gas-share, and when the OOA occurs, you may well have exceeded your NDL and have a mandatory deco stop or be right at the line of mandatory deco.
That example is a perfectly normal AOW level wreck dive in NC and that is one of a mountain of ~200ft long wrecks in ~100ft of water that usually have current, and can have unpredictable current. I consider that a mandatory part of my rock bottom plan and when off the coast I set turn pressures from the anchor line as if I was in an overhead environment because there is no way I'm willingly making a direct ascent from those wrecks.

Drift diving in Pompano? Looe Key with no current? Lakes/Quarries? Different variables because your planned gas requirements may not be 6 minutes at the bottom to fix the issue and get back to the anchor line, it may only be a 2 minute conflict resolution then direct ascent, but I'd always plan for 5 minutes at 15ft. Better to have and not need, than to need and not have

 

[tursiops]

The scenario you describe above involves two simultaneous failures/problems. The buddy looses all gas supply and then the donor with the pony bottle ALSO has a total failure of a scuba unit.

It is my understanding that in recreational diving, we generally will assume ONE failure in a buddy team - and then implement a plan to get the team to the surface. For example, a buddy team without a pony will be in trouble if BOTH divers loose their gas supply. So this simultaneous failure is outside of the recreational emergency planning scenarios that I am familiar with.

If we are talking about recreational diving, I think we need to be somewhat consistent in our assumptions.

Also the statement (by others?) that a 13 cu-ft tank will require a super fast ascent from recreational depth is clearly incorrect. The math proves that point. The assumption that a diver would need to swim horizontally to acquire an ascent line/anchor line and also perform a safety stop seems rather extreme. Recreational divers are assumed to go directly to the surface when an emergency occurs. If that option is not available (in an emergency) then the diving activity should probably not be considered recreational.

It is unclear to me why some people want to diverge from recreational assumptions, when the scenarios involve recreational diving?

I'm glad you liked the discussion. Unfortunately, I can't

For most of the diving I do, 6cf would be adequate.... Me owning a 19 is due to factors that include more than just the diving.
I believe we have reached the point of "agree to disagree" and "dive and let dive."
I genuinely do thank you for the debate and discussion on the subject.
Respectfully,
James

Just what were we debating? I still have no idea what we disagree on. What are you taking issue with?

 

[johndiver999]

wreck diving in current. Common in recreational diving up in this neck of the woods. U352 is a good example. 110ft to the sand, wreck is 218ft long. If the boat is tied into the bow, and you have an issue at the stern and you try to make a direct ascent, you're going to quickly find out how effective your DSMB or PLB is. Fairly strong current, 3atm's to ascent, and if things aren't in your favor, the wreck could easily be a quarter mile away from where you pop up. On the safety stop and the need to plan for it. Depending on how long it takes you to get everything stabilized and start moving, combined with generally slower travel speeds when in a gas-share, and when the OOA occurs, you may well have exceeded your NDL and have a mandatory deco stop or be right at the line of mandatory deco.
That example is a perfectly normal AOW level wreck dive in NC and that is one of a mountain of ~200ft long wrecks in ~100ft of water that usually have current, and can have unpredictable current. I consider that a mandatory part of my rock bottom plan and when off the coast I set turn pressures from the anchor line as if I was in an overhead environment because there is no way I'm willingly making a direct ascent from those wrecks.

Drift diving in Pompano? Looe Key with no current? Lakes/Quarries? Different variables because your planned gas requirements may not be 6 minutes at the bottom to fix the issue and get back to the anchor line, it may only be a 2 minute conflict resolution then direct ascent, but I'd always plan for 5 minutes at 15ft. Better to have and not need, than to need and not have

I understand all of that and I reject it. If a very rare and unusual failure occurs for a recreational diver, then they should be able to go UP.

If you want to analyze a scenario (or prepare contingencies) where a direct ascent is not a viable, (emergency) option, then that is fine - maybe even smart, but again, it is outside of the typical recreational diving parameters.

Edit: Also, a very simple and workable solution to the scenario you presented is to carry a reel and smb. If the diver has a problem on the downstream end of the wreck, they should be able to start the ascent, and immediately launch the smb from depth. The smb should hit the surface VERY quickly and close to the wreck - especially if it is only a few hundred feet long. With a reasonable amount of scope on the anchor line, the dive boat could be sitting behind the wreck and the crew should be looking for EXACTLY this type of incident to occur.

 

[tbone1004]

@johndiver999 how is that outside of the typical recreational diving parameters? Thousands of recreational divers do that dive every season in NC with nothing more than an AOW card.

Also, while you should launch an SMB as soon as it happens, it may be half an hour before the boat can actually start moving to go get you. They have to wait for all divers to get back on board, and manually get unhooked from the wreck since they are tied in vs. an anchor that you can haul up. All of that takes time before they can move and depending on sea conditions and surface current, you may well be a long way away. Sure they're going to find you, but it will be rather unpleasant until they do.

All of that to justify not carrying a sufficiently large bottle that you could have traversed back to the anchor line. I don't understand why people continue to defend inadequate gas reserves. Plan for the worst, hope for the best. If you're going to carry a pony instead of doubles, the difference between a 19 and a 40 is not enough to start defending inadequate reserves.

 

[rjack321]

I understand all of that and I reject it. If a very rare and unusual failure occurs for a recreational diver, then they should be able to go UP.

If you want to analyze a scenario (or prepare contingencies) where a direct ascent is not a viable, (emergency) option, then that is fine - maybe even smart, but again, it is outside of the typical recreational diving parameters.

Edit: Also, a very simple and workable solution to the scenario you presented is to carry a reel and smb. If the diver has a problem on the downstream end of the wreck, they should be able to start the ascent, and immediately launch the smb from depth. The smb should hit the surface VERY quickly and close to the wreck - especially if it is only a few hundred feet long. With a reasonable amount of scope on the anchor line, the dive boat could be sitting behind the wreck and the crew should be looking for EXACTLY this type of incident to occur.

I know at least 4 divers for whom 13cf was not enough to get to the surface. They're dead now so hard to ask them if they would prefer only bringing 19 or if 30 or 40 would be their preferred reserve. Most divers use more as than they planned on to get into the OOA or other problem situation in the first place - so carrying the bare minimum to get out of it doesn't always work out.

 

[boulderjohn]

First, the AL19 pony I use is more than adequate for me to get to the surface from any recreational depth.

A CESA is adequate to get you to the surface from any recreational depth.

I know at least 4 divers for whom 13cf was not enough to get to the surface. They're dead now so hard to ask them if they would prefer only bringing 19 or if 30 or 40 would be their preferred reserve. Most divers use more as than they planned on to get into the OOA or other problem situation in the first place - so carrying the bare minimum to get out of it doesn't always work out.

I don't understand why, if you are going to carry an extra cylinder, you don't go for something that will do the job in all situations. I rarely use what I will call a pony for this post, but when I do, it is an AL 40, which could be anything I want it to be.

Why did I hesitate to call the bottle I carry a "pony" for this post? Because when I use it, I use it in a variety of ways.

• In recreational diving, I usually have loads of gas, but if I want more than is in the cylinder on my back, I can use some of what is in the AL 40 at the beginning of the dive, making it a stage bottle. When I switch to back gas, that stage bottle is magically transformed into a pony bottle, still with plenty of gas to serve that purpose.
• Usually I have a richer oxygen mix in it, and I use it during the upper part of the descent, making it a deco bottle, even if I have not actually gone into deco.
• In that last scenario, you can argue that on the deepest part of the dive, it is no longer available to me as a pony. Under that theory, for a portion of the dive I have no pony, but for the shallower portion of the dive, I am carrying both a pony and a deco bottle in one. I think that in open water, a lot of people would have no qualms about switch to, say, 40% at 100 feet in an emergency as they ascended to the correct MOD.

 

[rjack321]

I don't understand why, if you are going to carry an extra cylinder, you don't go for something that will do the job in all situations. I rarely use what I will call a pony for this post, but when I do, it is an AL 40, which could be anything I want it to be.

The smallest bailout I will use diving CCR is a 40. And that's for <100ft recreational dives. I end up using some of that gas in my drysuit so its really like 35-37cf depending on exactly how full it was when I started and if we're on our second dive of the day or not

 

[johndiver999]

I know at least 4 divers for whom 13cf was not enough to get to the surface. They're dead now so hard to ask them if they would prefer only bringing 19 or if 30 or 40 would be their preferred reserve. Most divers use more as than they planned on to get into the OOA or other problem situation in the first place - so carrying the bare minimum to get out of it doesn't always work out.

Sorry to hear about all those dead divers. Were they doing recreational dives? Why were they not able to ascend in a controlled manner?

 

[tursiops]

Sorry to hear about all those dead divers. Were they doing recreational dives? Why were they not able to ascend in a controlled manner?