How deep until you need to bring along a pony bottle?

[AquaGuy]

Thanks everyone for your suggestions. I did not think such a simple question could get so complex. I do see both views on this (pony vs doubles). I sometimes have to walk 1/2 mile when shore diving with all of my gear on so that puts doubles out of the question. A 30/40 cf pony bottle makes a lot more sense to me. Sure, it may not hold as much gas as a set of doubles, but I am only looking for enough gas to get me out of an emergency situation.

Another question about ponies: Do you really need a seperate SPG attached to your bc or will one of those cheap spg's that plug directory into the HP port on your first stage be enough?

Thanks for all the help. SB ROCKS!

 

[Genesis]

I use a regular SPG on a 6" HP hose bent back to the reg and secured with a loop of cave line. The entire rig (first, SPG and second on an octo-length hose) is a "unit"; you only need to "stuff" the hose down into a couple of loops of bungie cord around the tank to make it "ready to draw".

The spg rigged this way is "in your face", is easy to read, and as accurate as any other SPG. The "button gauges" have the problem of being real small and impossible to accurately read - they only give you a "full / not full" indication, really. They also invariably are facing the wrong direction when you need to look at them - a regular SPG on a 6" hose still has the spool in it and swivels so its pointing right at you when the pony is clipped off on your BC. A glance at it and you know immediately how much gas is in there.

 

[double125's]

For what it is worth I never used an spg on a pony. My pony was for emergencies only. I would check the pressure with my regular setup to ensure it was full, then I would switch over to a regulater with just the first/second stage (hope that makes sense the way I explained it.) I was using mine strictly for back-up and not as a stage bottle so to me there was no need to know the exact contents.

 

[AquaDog]

I have my own guideline. Any dive below 50 fsw AND an overhead evironment, then I use my 19 cf pony. I wear mine across the front of my torso without any problems.

Dive hard,
AquaDog

 

[MHK]

MASS-Diver once bubbled...
Aren't there some situations where doubles are overkill and a pony bottle has it's place? For example, if I'm going to be doing a penetration of a shallow wreck <30' off a small boat and probably only using 40-50cu of air total, why should I lug along doubles instead of an AL80 or a steel 100 w/ a 40cu pony?

Isn't diving with a pony slung good practice for future stage compression?

I think it's such a subjective point that it's very difficult to dissect the issue in two. I'm not sure what you mean by "overkill", it seems to me that doubles aren't para-military equipment and are quit simple and easy.. I think that many that have never dove doubles, or who are unaccustomed to the using them overestimate their complexity.. I'm sure for certain that there are "easy" dives like you offer in 30' of Cayman like conditions, but part of what I'm trying to illustrate is that by building the muscle memory and by recongnizing that approaching an overhead environment should automatically trigger in your mind that OE = doubles... As for dives in the 100' - 130' range, for my prefereance I generally always use doubles, so maybe a better way to explain it is that it's how I approach a dive, not necessarily a dissection of the minutae..

Does that explain it any better???

Later

 

[DiverBuoy]

I think fundamentally the question is at what depth and under what conditions does one dive with a redundant system? Local shops and divers in our area typically use a redundant air source below 80' or anytime you are in an overhead environment where direct access to the surface is not available or where a Controlled Emergency Swimming Ascent cannot be performed.

There is no written rule, a redundant rig fit for your typical diving environment is not that expensive or cumbersome. Diving regularly with one is always a good idea - IMO. But there are those that believe a pony bottle, or especially a spare air, is a gross underestimation of the redundant air requirements of deep, wreck or cavern diving. Such individuals liken it to having a fire extinguisher designed for use in your car on hand in the event of an emergency in a commercial/industrial kitchen.

I'd disagree with any points in this thread that feel redundant air whatever form it takes is ever "overkill" ... that just seems shortsighted.

 

[MASS-Diver]

I understand your point and it's well taken.

Nonetheless, what I meant by overkill wasn't so much t the extra weight of doubles - which can be a problem if you have a hike or if you are in small boat with a limited or non-existent crew, my point was moreover, that, if when I do my gas planning - and determine how much gas I'm going to use then apply the rule of 1/3s, halves, rock bottom or whatever is right for that dive, that's how much air I want. I don't want to carry an extra 100cu of air of air- that's overkill and it's not an advantage.

In general I agree that using a pony when doubles are really needed is a problem, I just feel their are some situation when grabbing a 40cu pony is a good idea.

Now, most of these situations would invlove non-DIR situations to begin with, but, what the heck I'll throw out one anyways:

solo shallow dive - again why lug the doubles to site to only use 1/4 of the air in them , why not grab the al 80 and a 40cu - plus without a buddy you don't need air to share either (so gass requirments are even lower)

 

[Rob Meddes]

A pony should really only be used for an AAS on normal no deco dives. It shouldn't be a tool to go deeper or longer than your normal limits. If you dive to 40m now for 7 minutes now then with a pony you should still dive to 40m for 7 mins. If you wish to go deeper or longer then you need to be looking at a twinset & extra training. Too many people think a pony means they can go into deco because its a redundant air scource. I wouldn't want to ascend from 40m with 15mins deco with only a 3 litre pony for air.
Good diving
Rob

 

[plsdiver4377]

IMO total redundancy is never overkill, regardless of the depth of the dive (as long as you have enough gas to make it to the surface with appropriate stops). I agree that good planning and buddy skills should be practiced at all times. I also trust my normal buddy implicitly(shes my wife). But there is one more thing I have to consider and that is her safety as well.

For instance, I have an o-ring go and lose all my air. My buddy is there but at this point I'm a little excited to say the least, so she shares air with me. My excited state and the fact that I'm a bit of an air-hog will wipe out her remaining back-gas at an extraordinarily rapid pace. This endangers her life as well as mine.

This is not an option! (If I have anything to say about it.)

Therefor slinging a 19, 30, or 40 cf pony (depending on depth and type of dive) is just another piece of safety gear I carry. My 2 cents worth.

:mean:

 

[pt40fathoms]

the type of diving you are planning to do, are the two main deciding factors.

My personal preference is any dive over 60 feet or any overhead environment dive, and I carry a pony bottle. (wrecks, ice dives etc...) I look at it this way, if anything were to happen I would rather end a dive and surface normally, than have to do an emergency ascent. In any overhead environment the question of full redundancy is just not a question. In my dictionary, bailing out of a dive and ending a dive mean the same thing. I just carry the equipment needed to make this a reality.

As for an SPG on the pony. I prefer an SPG with its hose strapped to the second stage hose. So When I grab it I not only have air, I can see how much I have as well. Again that is just personal preference, but it makes since. As for doubles with an isolation valve and two set of regs. They have a place as well, not for every dive scenario of course, but for some types of diving they are the most practical. Given a choice of a good pony bottle set up that can be transferred to any tank, or a set of doubles with an isolation valve and twin regs. I would have to say that I would choose the pony bottle set up first, and get the twins later.