Cozumel OOA

[MikeFerrara]

Question -- do the folks who use a big "pony" also carry enough lead to compensate for the change in buoyancy if you actually had to use that air source? In other words, do you carry roughly an extra 6 lbs of lead (an AL80's worth of air), so that at the start of a dive you're around -11 to -12 lb, and at the end of the dive around -6 lb?

By definition, when I need a pony it has hit the fan. The last thing I would want is to be placed in an uncontrolled ascent condition. That means I carry enough lead to compensate for the delta if I actually have to use my pony.

I think I'll stick with my 19CF...

Most al 80's are going to be 2 or 3 pounds pos when empty. With reg and rigging it will be less. If you are correctly weighted with the single tank on your back (neutral with a near empty tank) then you'll only be that same 2 pounds pos if you empty EVERYTHING. However, you'll be a little heavy when they are both full. If you empty the slung 80 (it's not really a stage in this context) and the 2 pounds of additional buoyancy is a problem, just let it go...but if you emptied everything this has been one really bad dive anyway.

 

[WeekendDiver]

Not neccesarily deep, but in general pretty aggressive. Going deep for the sake of going deep (assuming a non-training dive) is not wise. On this most recent coz trip I did the Felipe Xicotencatl as the 5th dive of the day. One of the DMs and I buddied up and we crawled all over that thing. The other divers went up after 35-40 minutes because they hit 500 psi. Most time was spend in the 50-60 foot range. We had a bottom time of 72 minutes during which my 'puter went into deco. We had discussed this scenario before hand and had agreed that once I went into deco we'd start making our way towards the line and start going up. Including a 5 minute stop at about 17 feet or so I came up with a tad over 800psi. The next day's dive were obviously way, way within NDLs, and I used nitrox even on 40 foot dives. Aggressive does not equate to stupid (or deep for that matter). Right now I am working on my trimix certification for a bit more flexibility in my profiles.

 

[markfm]

It's just that the whole thought of schlepping an 80 as a pony hurts my head.

Dry (land) weight is a pain, there really is potential for a full 6 lb swing, then you have to add lead to your off side to compensate for the list the tank would tend to produce. (being around -3 on your left side relative to your right is noticeable, at least to me)

End of the day, if someone is willing to take along an extra 80 as a "pony", super, it's better than no redundant gas, but a normal pony is just easier to use for OW dives.

Different strokes for different folks...

 

[MikeFerrara]

It's just that the whole thought of schlepping an 80 as a pony hurts my head.

Dry (land) weight is a pain, there really is potential for a full 6 lb swing, then you have to add lead to your off side to compensate for the list the tank would tend to produce. (being around -3 on your left side relative to your right is noticeable, at least to me)

End of the day, if someone is willing to take along an extra 80 as a "pony", super, it's better than no redundant gas, but a normal pony is just easier to use for OW dives.

Different strokes for different folks...

Slinging an 80 is no big deal. I usually have 2 of them on my left side.

If I felt the need for redundancy and I couldn't have my doubles, I'd rent an extra 80, sling it and dive the two tanks like independant doubles, going back and forth between them and keeping some reverve in each. You don't know which one will fail do you?

Pponies are for litte people to ride. I don't carry them.

 

[ArcticDiver]

As far as I'm concerned you have your brain in high gear. For the same reason you sling a local AL80 I'm checking out putting it on my back. A person can think of the two tanks on my back as Independent Doubles; or as a Tank with a Full Size Pony.

The bracket was relatively cheap. I don't have to worry about TSA regulations. I don't have to take up precious baggage space and weight. It dives like a dream. I can dive either by taking air out of each tank alternately; or by breathing my Primary Tank down and not touching the other one.

Unless doing two deep dives back to back I only need two tanks for the typical two-tank tourist charter. If it is planned for back to back deep dives I just ask for a third tank to be brought along.

 

[WeekendDiver]

The reason why I sling it and don't use them as independent doubles is because I in non tropical diving I dive doubles and sling an 80 with 50/50. It's certainly an interesting approach though and I had not thought of that.
MikeFerrara: when you use your slung 80 doesn't it get annoyingly positive when you use it and it's butt starts floating up? hanging on a line is one thing, but just swimming around looking at fishies, isn't that a PITA?