Redundant air with a drysuit

[doctormike]

I agree Mike, just putting all the variables on the table. As I said, I wouldn’t bother myself but there are circumstances where it might be an option, if so then a stowed inflator whip shouldn’t be an issue.

To be clear, generally speaking, you shouldn’t need to bother with a pony to drysuit connection. However if you do feel you need one then be sure to practice the use of it and be aware of the downsides involved.

Right. And I agree that people should be comfortable with manipulating LP hoses, so practicing that in general is a good idea.

Being able to disconnect an LP hose is a critical skill to prevent a runaway ascent in cases of a stuck open inflator valve (dry suit or BC). I believe that one of the recent Doria deaths was related to that. It was one of my CCR training skills; not always stressed in OC training, in my experience.

 

[davehicks]

As a rebreather diver I do use my 40CF pony for dry suit inflation. The pony is on 100% of the time as it is also my offboard DIL and bailout. My only alternative would be a seperate inflation cylinder which is just extra stuff. Suit inflation uses negligable gas per dive.

For open circuit I would NOT use the pony for suit inflation for a couple of reasons:
* If for any reason you need to leave the pony behind, you will need an inflator on our main tank anyway.
* A nice benefit of a pony is you can hand off the entire tank to a buddy in an out of air situation. An inflator connection would get in the way.
* I have forgotten to re-attach my dry suit hose after a warm water trip. Backup is good!
* You might want to the have LP inflator hose on your pony even if you don't use it. SMB inflation, or Air Blower fitting

 

[dhaines429]

Pretty much everyone around where I live dives dry and I haven't seen anyone have an inflator whip on a pony. As pointed out if you are going to pony the dive is over and you are ascending and on surface you would orally inflate BCD for bouyancy.

 

[Darcimus]

Soon to be a new drysuit owner, and one of the things I started wondering about was the use of redundant air with a drysuit. I have no plans of going to doubles, but do sometimes carry a 40CF for redundancy.

This may be a stupid question, but do people put an inflator hose on their redundant air for their drysuit since there is no oral inflator? I suspect not, but you never know.

First of all, I would hope that you're taking the pony along for breathing air in the event of an emergency and you're not factoring that air into your breathing air calculations. Second, that air is normally meant for life support in an ascent when your back gas experiences a failure. At this point, that air is all you have, and you should probably hope that you have all of it.

I get that a 40 is a lot of air to take as a backup, but the primary purpose of that bottle is to sustain life on the way up. Not inflate your suit (which you shouldn't need anyways.) I recently bought a 40 that I intend to use as a backup on deeper dives, but I'll be using that only as breathing air.

The stowed whip to inflate your suit is something I've never thought about before. Would you necessarily need that if your BC is working well and you can still orally inflate that at the surface? I'd probably only add one if I thought my BC was going to fail also. Guess you never can be too safe, but the whip itself is another potential failure point, and if it's not attached to anything you'd have to make sure you're cleaning it regularly so it's not too gummed up when you need to use it.

 

[gcarter]

First of all, I would hope that you're taking the pony along for breathing air in the event of an emergency and you're not factoring that air into your breathing air calculations. Second, that air is normally meant for life support in an ascent when your back gas experiences a failure. At this point, that air is all you have, and you should probably hope that you have all of it.

I get that a 40 is a lot of air to take as a backup, but the primary purpose of that bottle is to sustain life on the way up. Not inflate your suit (which you shouldn't need anyways.) I recently bought a 40 that I intend to use as a backup on deeper dives, but I'll be using that only as breathing air.

This I will take issue with.

A slung 40CF bottle - or any slung bottle for that matter - can and will be used as I see fit. I may plan it for redundancy or I may plan it as part of my dive gas. I can call it a pony or I can call it a stage, but I will dive it as I plan it; that will determine what it is meant for.

The primary purpose of that tank is what I choose it to be, not what you choose it to be. I did not ask for a lecture on the permissible use of a 40CF cylinder, and I will not follow you further down this rat hole.

Dive and let dive..

 

[Darcimus]

This I will take issue with.

A slung 40CF bottle - or any slung bottle for that matter - can and will be used as I see fit. I may plan it for redundancy or I may plan it as part of my dive gas. I can call it a pony or I can call it a stage, but I will dive it as I plan it; that will determine what it is meant for.

The primary purpose of that tank is what I choose it to be, not what you choose it to be. I did not ask for a lecture on the permissible use of a 40CF cylinder, and I will not follow you further down this rat hole.

Dive and let dive..

Not trying to start an argument. You're right, you can do with it what you want. My opinion is that if I take it along on every dive and never use it as part of my calculations is that when I need it, the entire air is always going to be there for me. It's a safety margin that I personally won't factor into my breathing gas for the dive.

 

[doctormike]

This I will take issue with.

A slung 40CF bottle - or any slung bottle for that matter - can and will be used as I see fit. I may plan it for redundancy or I may plan it as part of my dive gas. I can call it a pony or I can call it a stage, but I will dive it as I plan it; that will determine what it is meant for.

The primary purpose of that tank is what I choose it to be, not what you choose it to be. I did not ask for a lecture on the permissible use of a 40CF cylinder, and I will not follow you further down this rat hole.

Dive and let dive..

You can use a slung 40 as a pony bottle (redundant gas supply for a single tank diver), as a stage bottle (extra gas included in the dive plan), as a deco bottle (rich mix for accelerated decompression) or as a bailout bottle (backup if your rebreather stops being a rebreather).

But you are a single tank diver and you asked a question about a 40 slung as a redundant gas source. So that's a pony bottle. That's what your question was about. You may not want a lecture, but when someone answers (politely and in good faith) by saying that your pony bottle shouldn't be used for anything than a redundant gas supply, that's a pretty reasonable comment.

Yeah, you can do whatever you want with your bottles, there are no scuba police. But a snarky response to someone genuinely trying to help doesn't make people want to try to help again.

 

[gcarter]

The response was a gratuitous lecture about how to use the tank and had nothing to do with the question asked.

I did not find it helpful.

YMMV.

 

[doctormike]

The response was a gratuitous lecture about how to use the tank and had nothing to do with the question asked.

I did not find it helpful.

YMMV.

Dunno.

You asked if it was OK to use your redundant gas supply for something other than an out of gas emergency.

Darcimus replied that his opinion was that it is not OK to use your redundant gas supply for something other than an out of gas emergency. And then he told you why he thought that.

I mean, maybe you don't agree with him, but I still don't see how it is off topic.

 

[gcarter]

Dunno.

You asked if it was OK to use your redundant gas supply for something other than an out of gas emergency.

Darcimus replied that his opinion was that it is not OK to use your redundant gas supply for something other than an out of gas emergency. And then he told you why he thought that.

I mean, maybe you don't agree with him, but I still don't see how it is off topic.

Incorrect. The question related to providing redundancy for dry suit inflation, hence the reference to the lack of an oral inflator.