Doubles or Pony

[ianr33]

My choice would be independant Al 80 doubles. Plenty of gas and true redundancy.
With regular,manifolded ,doubles breaking the isolator (although very unlikely) would probably kill you. A free flow or burst low pressure hose will empty the tanks in 1-2 minutes if you dont close the appropriate valve in time.

Alternatively you could use an 80 on your back and sling a second 80 as a "poor mans independant doubles" Not as elegant but saves having to get a doubles wing and bands.

I would breathe each tank down to a minimum of 1500 psi before starting the ascent. That will give you 30 minutes at 100 feet with a SAC of 0.6. In the event of a gear failure just before turning the dive you will still have 40 cu ft of gas in each tank to make a slow ascent/deco stops with.

 

[TheRedHead]

I like the way doubles dive, myself. But I have to admit I've never dived with a pony.

My personal preference is an HP 100 with an AL 80 slung for minor deco. You can hand off the 80 and don't have to climb the ladder in doubles. That's a Coz tihng, I think.

 

[drbill]

redundant in a way that I dont have to worry about a first stage failure , which is my primary concern , not running out of air.

True, first stage failure would be resolved with an H-valve.

However, I assume you've never had a tank valve clog and in my experience that has happened with the same frequency. An H-valve would be of no use in that event.

Diving in the depth range you are, you should get by easily with a tank in the 100-120 range and a 19 cu ft bailout if you're not getting into deco. Of course it never hurts to have more gas than you could possibly use. If you're doing deco dives, a larger pony might be necessary or doubles.

 

[Miami_Diver]

You said you wanted a redundant SOURCE. The source is the tank. The reg is simply a conduit.

mostly worry about first stage failure but the extra gas is fine.

 

[scubak]

I never used a pony except once and it sucked...I mean, what is the point?
Just jump to doubles (twins) and be done with it.
You can grow with twins, you will out grow a pony.
Just my .02 cents.
K

 

[dumpsterDiver]

I dive similar dives in Florida. For no-deco dives, I would definitely get a pony NOT doubles. Why pay double for fills and deal with all the extra weight of doubles? Doubles will just slow you down underwater, unless you are a total air hog or need it for deco dives. The increased air consumption with the drag and significant added difficulty of existing the water with doubles are other negatives to consider.

I am not particularly good on air and generally choose to use a large single steel tank and a 13 cu-ft pony bottle. I just got a new 149 cu-ft steel and it is working out nicely, but this is much more air then I would need for a solo, no-deco dives.

 

[Squid]

My main tank is a 100CF HP steel, but I'm probably going to get another 120CF HP steel for deep dives. I'm getting a 23CF HP steel pony for a back up. It's only about 4" in diameter and it should tuck in nicely to my main tank. I can balance the weight with some lead in the opposite side of my BC. I'm also thinking of getting a pony tamer bracket which will allow the whole unit to be disconnected. I was originally thinking of slinging it, but I don't think I want to deal with it hanging off the front of my BC all the time.

 

[Jimmer]

I use doubles esclusively, unless with students (working towards my DM), and I prefer them in the water. To me they feel nicer, trim nicer, more stable. Now I also carry a slung al40 on some dives, partially to just get used to the feeling of it for future tech training, and partially to help with off gassing. I will usually fill my pony with 40%, and switch to it at 100' during the ascent, while maintaining a standard NDL following my backgas planning. This way I will come out of the water "cleaner" than is I was breathing my backgas the whole time.

 

[alwaingold]

However, I assume you've never had a tank valve clog and in my experience that has happened with the same frequency.

Just out of curiosity, has this happened in tanks you own (and take care of) or in tanks you have rented from sketchy sources?

 

[Miami_Diver]

Ive never heard of a tank valve clogging either,and Ive been diving for 10 years; yesterday I bought double aluminum 80s,with manifold isolator and bands for $700, ouch!!!