pony vs large tank and h valve

[Max Speed]

Don't forget the clogged dip tube scenario...

 

[Dive Right In Scuba 2]

I personally use both an H valve and a pony. When properly attached, a pony doesn't add much to your rig. While H valves do add a small safety buffer, I wouldn't trust them for true redundancy.

 

[DogDiver]

Double discing solves the burst disc problem. Using a large wrench when installing a new valve oring solves that problem. Those that truly understand the principal of redundancy know why cave training (cavern & intro) start with a single high volume cylinder with an H Valve.


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[shoredivr]

Another answer: depends on the water temperature. Here in the Great Lakes the water below the thermocline is a toasty 40F now on the wrecks. In the past I dived steel H-valves if I was diving single tanks, so I could shut off a free-flow. Then I added a slung 30 for true redundancy.

Now I dive Sidemount and have the best of both worlds: first stages are easy to see and to shut down correctly if there's a free-flow. And there's redundancy.

 

[yardpro]

you can have a burst disc fail, you can have a tank neck O-ring fail... These could happen. Also, you have to realize that part of the danger of using an H-valve solo is that you MUST shut down one of the sides in a failure. Do you know how to do that? What happens if your hands are full of fish? What happens if you are fighting a fish, it drags you under a wreck and you cut one of the reg hoses at the first stage? How will you determine WHICH valve to shut down? You are alone and can not see what is happening?

I'm not telling you that "you are gonna die", but the H-valve is less safe AND REQUIRES you to do some analysis blind in a true emergency... screw it up and you may die.

If these or other scenarios do not come to mind immediately, then you shouldn't be solo diving...

you must not spearfish often the scenerios you present are a little absurd.....
your hands are never full of fish... they are on a stringer attached to your harness/bcd, etc. if i were handling a fish and something happened..... let go of the fish.. duh....
a fish drag you under a wreck... really? what kind of fish have you shot that drag you around....

if a line is cut it is instantly obvious which one it is... if i can still breathe it is the octo/ pressure gauge/ LPI as they are all on the outward (left). only my primary and the transmitter are on the other.

of course i know how to shut them down.. you turn the valve.. you wold have no business in the water if you don't know how to turn off a valve.

i can see the burst disk scenerio. but that is about as likely as me having a stroke under water...so i am not to concerned about that...

the dip tube i can see as the only real issue i could run into, but again, how common is that?

as far as the running out of air issue...come on guys, i am starting with around 150 cuft... i would have no more air with a 100 and a pony...
if you aren't managing your air and run out without any entanglement issue, with that much air, you should not be diving...
if i was entangled i would still have the still have the same volume of air...

as an example i had 1400 psi left on the last dive of 130' even going slightly into deco....

---------- Post added September 8th, 2014 at 06:03 PM ----------

no temp issue here...

water in the 80's now, and only get into the upper 50's in the winter... which is far too cold for me.

i do like the sidemount slung tanks, but i would think that that would get in the way for what i do.

 

[dumpsterDiver]

you must not spearfish often the scenerios you present are a little absurd.....
your hands are never full of fish... they are on a stringer attached to your harness/bcd, etc. if i were handling a fish and something happened..... let go of the fish.. duh....
a fish drag you under a wreck... really? what kind of fish have you shot that drag you around....

if a line is cut it is instantly obvious which one it is... if i can still breathe it is the octo/ pressure gauge/ LPI as they are all on the outward (left). only my primary and the transmitter are on the other.

of course i know how to shut them down.. you turn the valve.. you wold have no business in the water if you don't know how to turn off a valve.

i can see the burst disk scenerio. but that is about as likely as me having a stroke under water...so i am not to concerned about that...

the dip tube i can see as the only real issue i could run into, but again, how common is that?

as far as the running out of air issue...come on guys, i am starting with around 150 cuft... i would have no more air with a 100 and a pony...
if you aren't managing your air and run out without any entanglement issue, with that much air, you should not be diving...
if i was entangled i would still have the still have the same volume of air...

as an example i had 1400 psi left on the last dive of 130' even going slightly into deco....

---------- Post added September 8th, 2014 at 06:03 PM ----------

no temp issue here...

water in the 80's now, and only get into the upper 50's in the winter... which is far too cold for me.

i do like the sidemount slung tanks, but i would think that that would get in the way for what i do.

FYI, I do spearfish. I spearfish solo a lot. Fish can do wild things.

I've had 400 lb mono wrapped around my neck by a big fish faster than I could blink. i've had a big fish wrap me up in shooting line, then bash me in the face knocking my regulator out AND my mask OFF my head; I've had a 90 lb cobia wrap me up in the bottom and cause me to twist and sprain my ankle as i try to spin with him, I've had a 40 lb AJ wrap me up tighlty in 4o0 lb monofilament tieing me to a wreck at 80 feet while solo- and then I dropped my knife; some day, I may have my front tooth repaired, it has a decent chip out of it from bear hugging a grouper, I've had strong fish pull me into a wreck....i've shot a lot of fish, learned a lot of stuff the hard way and can tell you that there is a lot of ways spearfishing large fish solo, can go from zero to 100 mph in seconds... ever have a 20 lb fish try to hide between your legs when a 400 lb shark is trying to eat it????

As for you idea that you will know which hose line is cut... not necessarily. You could rip a large tear in a hose causing a serious loss of air, but it could still be delivering air... so you MIGHT not be so sure which valve to cut off .. as you work blindly and try not to drop the large fish.

And you STILL don't seem to understand the running out of air issue. You think a super large tank is as safe as a 100 and a 40 cuft pony bottle? If you are a dumbass and breath down a tank completely on the bottom.. you may be in trouble.. regardless of how big your tank is.. in fact breathing down a big tank may put you in more danger (than a small tank). Apparently this has to be spelled out for you, but if you are a dumbasss and use up all your air, the pony is a get out of jail card.. you just switch and come up... I've done that too myself FYI..


Edit: I also noticed you are doing solo, deco, spearfishing..I used to do the same with an h-valve (in significantly deeper water) .. I did it a few times and decided that the extra weight of a pony bottle was worth the weight and extra drag. You may decide otherwise, but you honestly seem to be lacking in imagination.

Anybody wanna buy some old Yoke Y-valves???

 

[haslamhoff]

My 2c ... Pony is a good way to go for redundancy, to be used as a bailout source only. If you are concerned about the clutter caused by slinging the pony, there are a few decent options for attaching it to your primary tank. This diminishes access to the pony, but it gets it out of the way.

I dive with a 30 this way on all dives, buddy or solo.

 

[rhwestfall]

Another answer: depends on the water temperature. Here in the Great Lakes the water below the thermocline is a toasty 40F now on the wrecks. In the past I dived steel H-valves if I was diving single tanks, so I could shut off a free-flow. Then I added a slung 30 for true redundancy.

^ +1

or, not stress a stage if I'm sharing with someone else.....

 

[uncfnp]

As others have pointed out, it's a question of redundancy, not gas volume. With the h valve you have redundancy for all but your tank/gas supply. Yes, a 120+ cf gives you a large primary gas volume but means little in the case of catastrophic gas loss, especially if that loss occurs near the end of the dive when a delayed response to an abrupt rupture or leak may mean too little gas left in the primary tank. And this is exactly the time when most divers would prefer not making a direct ascent without a safety stop.

As you pointed out, it's all a question of risk tolerance. But there really is no down side to a pony bottle. Your concern of interference/hazard with a slung bottle is solved by the tank mount option. And you can keep your 120 so you still have your full back gas volume plus the pony reserve. A win win scenario.

 

[jadairiii]

.....i run lp120's with h valves. .

Running a 120 and then adding a pony (40) to the mix, you would be better served to just switch over to twin Alu 80s with an isolator valve. You will find that the alum 80s are better balanced, easier to swim and will improve your trim without all the extra nonsense.

You look at these guys with one big steel tank then a extra pony or two, they have hoses going every which way and are completely vertical in the water, its a joke.