Y valve or pony?

[DMNick]

Hi all,

Recently I've been pondering with the notion of bail out / redundancy air methods.

The shop I regularly dive with provides for some customers, and recomends diving with a Y-valve on the cylinder and 2 x 1st stages.

I have the feeling that I would prefer to dive with a 6ltr pony bottle strapped to the main cylinder, but have no experience of either methods. I would imagine if either method required deploying, then the pony bottle would be easier (dive with valve open) as opposed to determining which of the 1st stages on the Y-valve to shut down, in a worst case scenario either not reaching the valves or even closing the wrong one.

I regularly dive 30-45mts, sometimes requiring up to a 10 min deco stop, I understand with this invisible ceiling a 6ltr pony bottle wouldn't suffice for a complete ascent with stops, but it would get me to the drop tank.

Thanks for taking the time to read,

Nick

 

[spectrum]

Hi Nick,

Lots of prior posts to draw on if you want to read a lot ASAP. Here are a few random thoughts......

I agree that making the Y effective requires more skill than using a pony.

A Y valve does not let you hand off to another diver but you can still share.

A Y valve does not represent extra air to cover a bad plan, delay, exertion etc.

The Y valve does represent a significant upgrade with very little extra clutter.

[-]AFAIAK a worthwhile pony is at least 19CF and you're playing in the 40 CF league.[/-] ( Missed the metric unit)

You mention strapping a 6 to your primary cylinder. One advantage of the slung pony beyond the mentioned hand off is that it's an optional grab and go item taken or not depending on the dive.

Pete

 

[Luis H]

The OP mentioned 6 liter (not 6 cubic feet). Assuming 200 bar fill that is equivalent to a 42 cubic feet (in US terms).

I am not sure what size of single tank the to OP is using for deco dives to 30-45mts (98 to 147 ft), but get ready for some serious feedback. There is going to be a lot of opinions on this.



(I could not find the popcorn icon)

 

[dumpsterDiver]

Hi all,

Recently I've been pondering with the notion of bail out / redundancy air methods.

The shop I regularly dive with provides for some customers, and recomends diving with a Y-valve on the cylinder and 2 x 1st stages.

I have the feeling that I would prefer to dive with a 6ltr pony bottle strapped to the main cylinder, but have no experience of either methods. I would imagine if either method required deploying, then the pony bottle would be easier (dive with valve open) as opposed to determining which of the 1st stages on the Y-valve to shut down, in a worst case scenario either not reaching the valves or even closing the wrong one.

I regularly dive 30-45mts, sometimes requiring up to a 10 min deco stop, I understand with this invisible ceiling a 6ltr pony bottle wouldn't suffice for a complete ascent with stops, but it would get me to the drop tank.

Thanks for taking the time to read,


Nick

I used to do similar profiles with Y-valves and I decided that I felt safer with a pony bottle. More trouble, more weight, more drag, but I think it is safe. If you are doing deco dives, I think your system should be robust enough to get you to the surface unbent, after a single failure AND without requiring that you somehow make it to a hang bottle in an emergency.


Anybody want to buy some Yoke Y-valves? I have several for sale.

 

[Diver0001]

The shop I regularly dive with provides for some customers, and recomends diving with a Y-valve on the cylinder and 2 x 1st stages.

It's an adequate solution for recreational diving provided you've had some training about how to actually USE that redundancy. Otherwise it's just a big-old sense of false security.

I have the feeling that I would prefer to dive with a 6ltr pony bottle strapped to the main cylinder, but have no experience of either methods. I would imagine if either method required deploying, then the pony bottle would be easier (dive with valve open) as opposed to determining which of the 1st stages on the Y-valve to shut down, in a worst case scenario either not reaching the valves or even closing the wrong one.

I'm not sure if you mean a 5l or a 7l bottle. In Europe there are no 6L bottles that I'm aware of. The 5L bottles are like the ones the fire department use and the 7 litre (especially aluminium ones) are common stage bottle format. In either case, attaching them to your main tank is not something I would advise. If you feel you want to go that way then you'd be better off with looking at twin 10's or twin 12's, which are common formats. A 10(or 15)+7 or 10/15+5 bailout is normally achieved by slinging the pony/stage.

If you're looking at doing staged deco dives with 10-15 minute hangs then I would think you will want to go with a a twin 10 or a twin 12 plus a 7 litre bottle of 50%.

R..

 

[flots am]

I regularly dive 30-45mts, sometimes requiring up to a 10 min deco stop, I understand with this invisible ceiling a 6ltr pony bottle wouldn't suffice for a complete ascent with stops, but it would get me to the drop tank.

There's "truly redundant" and then there's "everything else".

Especially with a deco obligation, you need to be carrying any gas you need, to get you to the surface safely from any point in the dive.

This means a separate cylinder and regulator. You'll need to do your own gas calculations to determine what size cylinder you need, since it depends on your planned depth, RMV and any deco obligation.

A "Y" valve won't help you if you get a blown tank o-ring, or run out of gas or get a clogged dip tube.

My best guess at why your dealer is pushing the Y valve is that they're easier to stock and are expensive.

flots

 

[Akimbo]

An advantage of a back-mounted pony is you can mount it valve-down at a height on your tank that is easy to reach. This has two advantages.

A physical impact that damages your primary regulator is far less likely to damage your backup — make sure the pony valve is high enough that the bottom of the main cylinder protects it. The “every dive” advantage of valve-down is you can jump in the water with the pony turned off so the second stage doesn’t free-flow. Just reach back and turn it on before descending.

To your main point, the depth you dive is a far more important factor than how long your dive lasts. An independent backup gas supply should be used when you are deeper than you can comfortably make a free ascent… assuming you are not committed to decompression or under hard overheads (wrecks or caves). This is a conservative approach since you can surface with a free-flowing regulator from significant depths. This article is worth reading to help understand the analysis:

Life Ending Seconds, 3000 to Zero in 72 Seconds

 

[grf88]

The advantage to a Y or H valve is that you can use the same reg setup for both singles and doubles without any changes. It does not provide the same redundancy as a pony but for the cold water diving I do a freeflow is much more likely than a blown neck o-ring or failed burst disk. When I do use a pony I use a 40 cu.ft. side slung.

 

[kwinter]

Anybody want to buy some Yoke Y-valves? I have several for sale.

Me too.

 

[lucca brassi]

I regularly dive 30-45mts, sometimes requiring up to a 10 min deco stop,

7lit alu stage