What pony size?

[Wookie]

What's the difference between accidental and unplanned?

Unplanned cuz you knew you were entering deco by helping?

In my little pea brain, accidental is preventable, and is caused by a complete lack of situational awareness of your depth, bottom time, and time remaining. Unplanned deco is when your buddy gets caught up in a shrimp net and you have to overstay your dive plan to get them out.

A pony bottle is not for either one. A pony bottle is for a failure of your primary gas supply, and is meant to get you to the surface when your o-ring blows out of your regulator or your LP hose fails.

If your situational awareness is so bad that you go into deco accidentally, you need to get more training. Or take up golf. Think of a pony as a reserve chute. You wouldn't normally use it skydiving, you wouldn't use it to extend or enhance your skydive, you'd use it when your main chute fails and leaves you approaching a sudden stop at 124 MPH, or 54 meters/second.

 

[Jim-SAR]

In my little pea brain, accidental is preventable, and is caused by a complete lack of situational awareness of your depth, bottom time, and time remaining. Unplanned deco is when your buddy gets caught up in a shrimp net and you have to overstay your dive plan to get them out.

A pony bottle is not for either one. A pony bottle is for a failure of your primary gas supply, and is meant to get you to the surface when your o-ring blows out of your regulator or your LP hose fails.

If your situational awareness is so bad that you go into deco accidentally, you need to get more training. Or take up golf. Think of a pony as a reserve chute. You wouldn't normally use it skydiving, you wouldn't use it to extend or enhance your skydive, you'd use it when your main chute fails and leaves you approaching a sudden stop at 32 ft/sec/sec.

That pretty much sums it up :cool2:
Bottom line - Carry whatever pony or redundant gas supply you feel like you need. If anybody gives you greif over it, just make sure you don't offer to share your air with them.

 

[skankpile]

There was a thread talking about ponies where someone posted an example gas usage calculation. Does anyone know what I'm talking about? Been trying to find it but can't.

If you know your SAC you calculate your RMV and gas/mix/bailout^2 requirements based on your plan and 3'rds etc. I like v-planner, and have my shearwater etc on vpm, and gradients set to closely match my v-planner profile.

I like 40cf tanks.. they are about neutral in the water and no fuss. A 13cft at 4ata (~100ft) = 1/4 the gas you thought you had so as long as you know you are coming straight up without obligation no problem. Another thing to think about is how often do you think you will maintain a full fill and be at capacity with pressurized regs on a smaller cylinder. May as well sling a 40 or go side-mount/banded pair IMO if you are looking for redundancy.

 

[uncfnp]

Say you have an "average" SAC of .7. Given a dive factor of 2 for stress that's an RMV of 1.4. Now factor in 2 minutes at depth (say 100 ft) to realize to situation, switch regs and catch your breath so to speak. Then about 1 minute to go to 40 feet and another 1 min or so to 15 feet. Now a 3 min safety stop plus a minute to surface. Thats...

1.4 (RMV) x 4 ata = 5.6 cf x 2 (mins) = 11.2 cf
1.4 x 2.8 ata = 3.9 cf x 1 (min) = 3.9 cf
1.4 x 1.75 ata = 2.45 cf x 1 (min)= 2.45 cf
1.4 x 1.5 ata = 2.1 cf x 3 (min) = 6.3 cf
1.4 x 1 ata = 1.4 cf x 1 (min) = 1.4 cf

Thats roughly 25 cf

Someone check my math...

 

[Panama Jones]

In my little pea brain, accidental is preventable, and is caused by a complete lack of situational awareness of your depth, bottom time, and time remaining. Unplanned deco is when your buddy gets caught up in a shrimp net and you have to overstay your dive plan to get them out.

A pony bottle is not for either one. A pony bottle is for a failure of your primary gas supply, and is meant to get you to the surface when your o-ring blows out of your regulator or your LP hose fails.

Ok. full credit for your definition or accidental vs. unplanned. At this point, unless you can clarify, I will respectfully disagree in that in with you in that you are only partially correct in that a pony is for neither one. I thought that a pony was for use as a backup in any situation where you do not have enough air to safely surface. The only stupid reason to be in this situation is that you weren't monitoring your air supply and ran low in a normal dive situation causing need for backup or CESA. This would include purposely diving outside your plan. In this case you should have your diver's licence suspended. And even then, it sure would be great if the stupid people had a pony.

You imply that the pony is there for technical failure only. In the case of the diver running into any situation causing you to overstay, you state that the pony is not for that. What is? I am assuming I am not going to leave my buddy in his situation because I do not have enough air to surface safely on my main supply and will refuse to use the pony as I am not in a technical failure.

Sorry to be challenging.

 

[GrumpyOldGuy]

Say you have an "average" SAC of .7. Given a dive factor of 2 for stress that's an RMV of 1.4. Now factor in 2 minutes at depth (say 100 ft) to realize to situation, switch regs and catch your breath so to speak. Then about 1 minute to go to 40 feet and another 1 min or so to 15 feet. Now a 3 min safety stop plus a minute to surface. Thats...

1.4 (RMV) x 4 ata = 5.6 cf x 2 (mins) = 11.2 cf
1.4 x 2.8 ata = 3.9 cf x 1 (min) = 3.9 cf
1.4 x 1.75 ata = 2.45 cf x 1 (min)= 2.45 cf
1.4 x 1.5 ata = 2.1 cf x 3 (min) = 6.3 cf
1.4 x 1 ata = 1.4 cf x 1 (min) = 1.4 cf

Thats roughly 25 cf

Someone check my math...

Your values are very conservative. Probably valid if you don't know what your SAC is and your a new diver, prone to stress.

Here is a similar set of numbers I would use for myself. My SAC is .4 in cold water, I still figure a stress rate but only to .7 cf/min
I also cut my bottom time. The time to realize there is a problem and make the reg switch is not breathing. Once I am breathing again, I am ascending since I don't do overhead. I am thinking like 10 seconds base on my drills but figure a minute for Murphy.

.7 (RMV) x 4 ata = 5.6 cf x 1 (min) = 2.8 cf
.7x 2.8 ata = 1.9 cf x 1 (min) = 1.9 cf
.7 x 1.75 ata = 1.23 cf x 1 (min)= 1.23 cf
.7 x 1.5 ata = 1.05 cf x 3 (min) = 3.15 cf
.7x 1 ata = .7 cf x 1 (min) = .7 cf

That's 10 cf, If you blow off the OPTIONAL safety stop its close to 7cu ft.

 

[redacted]

Ok. full credit for your definition or accidental vs. unplanned. At this point, unless you can clarify, I will respectfully disagree in that in with you in that you are only partially correct in that a pony is for neither one. I thought that a pony was for use as a backup in any situation where you do not have enough air to safely surface. The only stupid reason to be in this situation is that you weren't monitoring your air supply and ran low in a normal dive situation causing need for backup or CESA. This would include purposely diving outside your plan. In this case you should have your diver's licence suspended. And even then, it sure would be great if the stupid people had a pony.

You imply that the pony is there for technical failure only. In the case of the diver running into any situation causing you to overstay, you state that the pony is not for that. What is? I am assuming I am not going to leave my buddy in his situation because I do not have enough air to surface safely on my main supply and will refuse to use the pony as I am not in a technical failure.

Sorry to be challenging.

You carry a pony as a redundant air supply in the event of a failure of your primary air supply. Sure, you use it when the occasion arises including the occasion of your being stupid. But, if your reason for carrying a pony is because you think you may not monitor your gas supply adequately to avoid an OOA situation, then you need to trade your scuba gear in on golf clubs (and avoid water hazards). And, if you are planning a dive to 130 feet, you need to carefully plan that dive and its gas requirement for you and your buddy including contingencies.

 

[Panama Jones]

And, if you are planning a dive to 130 feet, you need to carefully plan that dive and its gas requirement for you and your buddy including contingencies.

There's the contingency word. best word used. Thanks..full agreement here

But, if your reason for carrying a pony is because you think you may not monitor your gas supply adequately to avoid an OOA situation, then you need to trade your scuba gear in on golf clubs (and avoid water hazards). .

I hope my post did not imply that I was saying this is a good reason because I thought I went to great lengths to agree with this thought.

 

[uncfnp]

Your values are very conservative. Probably valid if you don't know what your SAC is and your a new diver, prone to stress.
...//...

Agreed. Not having any numbers I chose over rather than under.

 

[Wookie]

Ok. full credit for your definition or accidental vs. unplanned. At this point, unless you can clarify, I will respectfully disagree in that in with you in that you are only partially correct in that a pony is for neither one. I thought that a pony was for use as a backup in any situation where you do not have enough air to safely surface. The only stupid reason to be in this situation is that you weren't monitoring your air supply and ran low in a normal dive situation causing need for backup or CESA. This would include purposely diving outside your plan. In this case you should have your diver's licence suspended. And even then, it sure would be great if the stupid people had a pony.

You imply that the pony is there for technical failure only. In the case of the diver running into any situation causing you to overstay, you state that the pony is not for that. What is? I am assuming I am not going to leave my buddy in his situation because I do not have enough air to surface safely on my main supply and will refuse to use the pony as I am not in a technical failure.

Sorry to be challenging.

Ah, we could talk about that all day, and the contingency cannot be planned for. That's why it is unplanned. Is an 80 enough to get your buddy (or you) unstuck? Is a 120? Is a 40? It is not anticipated that you will have a cave collapse, or a shrimp net descend on you, or any host of other things. That's why a pony isn't for those things. They can't be planned for.

Unless you go to a rebreather. They don't give you limitless gas, but used correctly they give you enough gas to send a buddy to the surface, get help, return with help, and get you unstuck. I'm not going to carry a rebreather as a bailout, therefore, I'm going with my pony, a 13CF aluminum bottle strapped to my main cylinder with a Metalsub Quick release, enough gas to get me safely to the surface in the event of a catastrophic failure of my main gas supply, not enough to save my life in the event of an unplanned event for which planning is not possible.

Sorry to be obtuse.