LP Inflator hose on pony ?

[RTee]

...and that is not considering that most divers also carry a SMB of some sort (my 3 footer is 10lbs lift and 6 footer, 20 lbs lift) with some of us also carrying a lift bag depending on the dive profile, that can all be, as a minimum, inflated either orally or with a reg.

1. BCD is used as primary buoyancy.

2. Drysuit is redundant buoyancy.

3. BCD oral inflation is the third redundancy option.

That's quite a lot of options at your disposal. Do you really* need a fourth?

*question assumes proper training and usage of equipment, proper weighting, balanced rig and application of safe diving practices.

 

[DaleC]

without rehashing that case here, I don't think you can take recent events as a good evaluation model. The buoyancy issue was not a need for a secondary inflation source, it was too much weight for the primary lift device. My solution would be to NEVER put yourself in a position rec diving where you need the combined lift of both systems at once.

Normally, as a rec diver one should plan for one failure, as the plan from that point forward would be to seek the surface and not continue the dive. So you could plan for a wing failure (use the drysuit for buoyancy) or a backgas failure (use the pony air to orally inflate the wing). Either of those would be addressed with a pony sans inflator. It would be stretching it to plan for backgas failure and a failure to be able to orally donated air from the pony - thus making LP inflation from the pony necessary.


But, in my case, if I am diving dry, equipment choices mean that I sometimes cannot inflate the suit from my backgas. Either I am using a doublehose with no LP ports or an early model single hose with limited LP ports. So, I put an inflator on the pony for my DS.

However, we should not pooh pooh the idea out of hand for normal rec diving either. It is a non standard configuration that does not seem to solve a problem but one could also say that a long hose/bungeed back up is in the same category. From the standard recreational configuration it could be seen (and is by BSAC for example) to be a complication (and yes I do dive one sometimes so I'm not anti LH).

If we could build the ultimate rec diving rig without any preconceptions as to what it should look like what might that be? Would it have one tank or two. Small twins, single with pony or large single with H valve. Would all inflation come off one post or both. Why do twinset divers route from both and if you do have two posts why route everything from one.

What concerns would we try to address with design. I am amazed that for rec diving, the major design feature for redundancy seems to be reliance on a buddy for something so vital as gas even though OOA accident after accident occurs. Comparison wise, how many accidents occur from someone using/not using an AAS. We always claim it's an error in diver planning/use but at what point do we look at how equipment could be altered as well as diver behavior - because if it were just a matter of diver behavior/skill we could all dive J valves without wings.

It's an interesting topic and something I spend a lot of time reading about and tinkering with in my workshop and in the water. It also isn't just black and white when it comes to design. Custom, economy of scale, robustness, financial incentive, inertia... all of those things can act to sink an otherwise perfectly sound idea.

 

[Stoo]

I see minimal additional complexity, but have never seen this done.

It's quite common here, but in a slightly different manifestation. On mix dives, many folks use argon to inflate their suits. Most are only using a 6 cf argon tank, so running out of gas isn't hard to imagine. So people have a "spare" LP whip on their left post with the end being loosely attached to the LP hose coming off the argon bottle. If the argon goes, you just change hoses. Of course it really isn't a spare whip... it's just the one they use when they aren't using argon.

I see no reason at all not to do what your suggesting. I guess my only cautionary comment is that if you are using an itty bitty pony (say a 13), I think you would be wise to spend your time making your way to the surface, rather than wussing around trying to change inflator hoses. Assuming you are properly weighted and trimmed, a couple of kicks upward is going to magically create positive lift and away you go.

 

[Bob DBF]

1. BCD is used as primary buoyancy.

2. Drysuit is redundant buoyancy.

3. BCD oral inflation is the third redundancy option.

That's quite a lot of options at your disposal. Do you really* need a fourth?

*question assumes proper training and usage of equipment, proper weighting, balanced rig and application of safe diving practices.

Oral inflation of the BCD is an alternative way to fill a BC not redundant buoyancy. If your BC is holed and will not hold air, oral inflation will not help you.


Bob
---------------------
I may be old, but I'm not dead yet.

 

[DevonDiver]

Oral inflation of the BCD is an alternative way to fill a BC not redundant buoyancy. If your BC is holed and will not hold air, oral inflation will not help you.

Mentioned as redundancy for the following OOA scenarios:

1) OOA primary and breathing from pony = buoyancy attainable via oral inflation.

2) OOA primary and air-sharing from buddy = buoyancy attainable via oral inflation.

Drysuit is a redundant buoyancy device.

Oral inflation is a redundant method of gaining buoyancy.

Either way, the drysuit diver has two buoyancy devices, and two methods of adding gas for buoyancy. That is sufficient for all reasonable scenarios.

The chance of simultaneous BCD failure + OOA + no buddy is beyond realistic need to address on a recreational scuba dive.

 

[String]

Lots of people talking about deco, tech diving and so on where the weight and other requirements are different. From what i can see its a simple question of adding a LPI to a redundant gas source, nothing more than that.
So in my view, no. Don't do it. It's a solution to a problem that simply doesn't exist. It adds extra O-rings to burst, an extra hose to potentially break therefore compromising your last ditch bail out supply for no reason.

Quite simply - get your weighting correct. Then you DO have enough lift to either orally inflate and/or begin a swim up and let expansion take care of the rest. Adding an LPI to a pony setup solves nothing and just increases the potential problems.

 

[Subcooled]

Am I missing something?

You should dive neutrally buoyant, which means that a swimming ascent is a good option. No suit gas needed for that.

I have run out of suit gas (small suit gas bottle), and I just continued my dive (without going deeper) and then ended the dive when that was possible. Not an issue.

If you are sinking, then the oral inflation technique is possible. You even have some time to do that, as suit squeeze is probably not an issue untill you sink at least 0.5-1 ATM. Well, at least I have dived 5m down from surface without suit gas and it went well.

Jumping into water with back gas closed and beeing negative would be a really bad experience, though.

 

[Linke Seitentasche]

Am I missing something?

I put an LP hose on my pony bottle for a simple reason: I want to be able to go down.

You read that right. A squeezing drysuit can be severly incapacitating, beginning from as little as a 1-2m descent, and there are a number of reasons why I'd want that in an emergency situation:

• While operating the valves of the bottle on my back, I might lose too much air from the suit for my current depth to stay neutral
• If I ascend to compensate, I might lose sight of the bottom terrain, since visibility can be 2m or less around here. While I agree that a diver must be trained to navigate without a visual reference, I prefer not to if I don't have to.
• On the other hand, I might have failed to keep neutral bouyancy and have already ascended too far until I regained control of the situation (e.g. 2fsw) and would prefer to do my safety stop at 5fsw.
  
• When things go wrong, you can expect other things to break, too. No one can guarantee that I'd never ever had to descend for a couple of metres.
• My buddy might need help.

Inhibiting my ability to be able to swim in every direction is not an option for me, even in an emergency.

 

[SoFlaDiver954]

I put an LP hose on my pony bottle for a simple reason: I want to be able to go down.

You read that right. A squeezing drysuit can be severly incapacitating, beginning from as little as a 1-2m descent, and there are a number of reasons why I'd want that in an emergency situation:

• While operating the valves of the bottle on my back, I might lose too much air from the suit for my current depth to stay neutral
• If I ascend to compensate, I might lose sight of the bottom terrain, since visibility can be 2m or less around here. While I agree that a diver must be trained to navigate without a visual reference, I prefer not to if I don't have to.
• On the other hand, I might have failed to keep neutral bouyancy and have already ascended too far until I regained control of the situation (e.g. 2fsw) and would prefer to do my safety stop at 5fsw.
  
• When things go wrong, you can expect other things to break, too. No one can guarantee that I'd never ever had to descend for a couple of metres.
• My buddy might need help.

Inhibiting my ability to be able to swim in every direction is not an option for me, even in an emergency.

I don't understand what you are getting at, what am I missing? You added an LPI so that you don't have to use it and are espousing benefits of suit squeeze? Not hating, just really trying to understand what you mean...

 

[Linke Seitentasche]

The consensus of the thread so far was that there's no reason for an LP hose on a pony bottle. Some people argued that the suit squeeze is no big deal.

I disagreed and thought I'd share some thoughts on why it's important to stay in complete control of your drysuit when you were forced to switch to your pony bottle.