What size tank for a pony??

[Hatul]

Skip the Spare Air.

 

[redacted]

You don't indicate the depth you plan to use it but assuming you don't want your pony to be the depth limiter, a 19 should work with not a lot to spare. It could still be packe and go with you for air travel without too much trouble. If air travel is not a consideration and you want more options for use, a 30 or 40 starts to make good sense. I can't think of any advantages of a 30 over a 40.

 

[Scoobers]

You don't indicate the depth you plan to use it but assuming you don't want your pony to be the depth limiter, a 19 should work with not a lot to spare. It could still be packe and go with you for air travel without too much trouble. If air travel is not a consideration and you want more options for use, a 30 or 40 starts to make good sense. I can't think of any advantages of a 30 over a 40.

I am currently diving to 80ft at least once a week. I live about 30 minutes from Lake Michigan so deep wreck diving isn't to far off... I am not planning on packing this tank for trips.

... and you thought you wouldn't get mixed opinions here?

Seriously (for a moment) ... the answer to most questions concerning SCUBA are going to be "it depends" ... with a bunch of other things to think about. That's just the nature of the activity.

First off, a .58 cfm consumption rate ain't bad for someone your size and experience level. And for typical recreational profiles, a 19 cf bottle will be all you need.

But whether that's the best choice for you depends on considerations of ...

1) how you want to mount it. For back-mount, anything bigger than a 19 cf bottle are going to impose some issues due to size and weight of the bottle. For slinging, a 30 or 40 cf cylinder are a better choice.

2) how you plan to use it. A slung bottle gives you some options you won't have with a back-mounted bottle ... such as the ability to pass it off to another diver in the event of an OOA. On the other hand, although a slung bottle virtually "disappears" if mounted properly, if you're diving in kelp frequently or tend to swim very close to the bottom, it has its own annoyances.

3) future goals ... as others have mentioned, if you plan to move into tech someday, you'll already have a handy deco bottle.

Personally, I prefer a slung 40 ... but it's partly because I'm used to carrying one anyway, and I already owned four of them. But I like the option to be able to manipulate the valve easily, readily see my pressure gauge, and hand it off in an emergency. Whether those are considerations that are important to you depends really on what kinds of dives you're doing ... and with whom.

... Bob (Grateful Diver)

No kelp in Michigan but we have some nice deep wrecks! But seriously I am going to sling it, I plan to use it mainly as redundancy but in the future I might want to use it for a deco bottle.

 

[elmer fudd]

Two things to keep in mind. You need significantly more air for greater depths. If you're coming up from 130' or deeper, you need more than twice the air as you would ascending from 65' as your risk of DCS is significantly greater. If I were diving no deeper than 60' I would probably opt for a 13 cf or even a SpareAir. :shocked2: For 100' I'd go for a 19 cf and deeper than 100' I'd be looking at the 30 or 40 cf bottles.

Second, the expensive part of the whole pony setup is the first and second stage regs and the SPG. Once you've got those it's not too expensive to pick up a second bottle later on. They're usually about $130.

 

[FritzCat66]

To the OP: Here, take advantage of the work ScubaBoarder derwoodwithasherwood has already done, after the approximately 3.7 bazillion discussions regarding this matter all over the boards.

Note that while this spreadsheet opens in OpenOffice's Calc, it seems not to work properly unless you use Excel.

 

[deepwater]

fritzcat did you spend all afternoon counting 3.7 bazillion posts?

 

[Doc Intrepid]

I also find myself agreeing with Dr Wu.

If you add the cost of a second regulator, a second SPG, a 40" hose and 6" hose, and the bottle itself (you will find that the costs seldom vary more than $30 or so between the 19 and the 30) you're looking at spending the better part of $400-$500 to meet a need that can be better dealt with by planning, situational awareness, and a buddy. Then you have to carry it around, get the tank inspected annually, and maintain the regulator annually, which can run you another $100 or more per year just in inspections and maintenance. Then of course you pay to fill it with nitrox.

Additionally, there is the matter of task loading underwater. Slinging the tank can create issues, at least initially. Its one more piece of gear to deal with. As a newer diver, you don't want to be the dude who looks like a yard sale on the boat and a circus underwater. Give it some consideration.

On the other hand, if you don't care about the money and want the piece of mind, then do the calcs. But recognize that, just like you breath heavy after a close call on the road, or after you run up a flight of stairs, under stress your respiratory rate is going to spike. Use a consumption rate of closer to 1.3 cfpm for your calcs, because if you get seriously anxious at 120 ffw or so you're going to chuff through some gas.

Finally, if you're going to drop that sort of ching, why not get something that will be multi-functional. At least a 40 can be used as a deco tank later on. A 19 is sort of worthless for anything but an argon tank, once you figure out that a bail-out bottle is not the way to go.

Best,

Doc

 

[Scoobers]

I already have the Regs, all I need is the tank its self. If I wasn't confident in my skills I wouldn't be purchasing the pony. I think I am going to go with the 30 cuft for now and when I am ready to upgrade to a deco bottle I will just buy another tank and pass the 30 down to my wife.

 

[Dr Wu]

If I wasn't confident in my skills I wouldn't be purchasing the pony.

If you had reason to be confidant in your skills you would not want the pony.

Seriously. You don't need it.

 

[scubadada]

A 19 cu ft pony should be sufficient to see you up from recreational depths. The math is pretty easy.

Good luck,
Craig