A Case for Spare Air

[tomfcrist]

So how does this compare with the 6 cu ft Spare Air?

For its intended use? Hose and reg make deployment easier. Mind you it’s for after your helicopter has crashed in the water, rolls over and starts sinking.

 

[Diver-Drex]

I use the tank for my second dive to initially fill my 6cf pony and then use the tank for my first dive to top it off. I am not a gas hog (.5cf working SAC, not resting RMV). So that works fine. Mostly, I get a shore dive tank before we dive for the initial fill-up.

I’m not following this. You fill the pony to 3000psi, assuming that your back pressure, for the first dive. And then connect it to a tank your breathes down. You’re dumping gas from the pony to equalize the pressures.

 

[ReefHound]

I’m not following this. You fill the pony to 3000psi, assuming that your back pressure, for the first dive. And then connect it to a tank your breathes down. You’re dumping gas from the pony to equalize the pressures.

"I use the tank for my second dive to initially fill my 6cf pony and then use the tank for my first dive to top it off. I am not a gas hog (.5cf working SAC, not resting RMV). So that works fine. Mostly, I get a shore dive tank before we dive for the initial fill-up."

He says "for" not from. I take it that he fills the pony from both tanks before any dives. The first 3000psi tank equalizes with about 2900 in each. Then the second 3000psi tank equalizes around 2990. In theory, first dive is usually deepest and should use the 2990 tank but reality is that 100psi difference shouldn't matter esp. since your original fill might vary from 2800-3200 in many places.

If he gets an initial fill from a tank for a practice shore dive at start of trip, then topping off from the two tanks won't pull but 10-20psi from them. Personally, if I had 2900 in the pony and 3000 in my other tanks, I'd not go to the trouble of hooking them up for another 80-90psi. If you completely deplete your pony then you picked the wrong size for your purposes.

 

[markmud]

"I use the tank for my second dive to initially fill my 6cf pony and then use the tank for my first dive to top it off. I am not a gas hog (.5cf working SAC, not resting RMV). So that works fine. Mostly, I get a shore dive tank before we dive for the initial fill-up."

He says "for" not from. I take it that he fills the pony from both tanks before any dives. The first 3000psi tank equalizes with about 2900 in each. Then the second 3000psi tank equalizes around 2990. In theory, first dive is usually deepest and should use the 2990 tank but reality is that 100psi difference shouldn't matter esp. since your original fill might vary from 2800-3200 in many places.

If he gets an initial fill from a tank for a practice shore dive at start of trip, then topping off from the two tanks won't pull but 10-20psi from them. Personally, if I had 2900 in the pony and 3000 in my other tanks, I'd not go to the trouble of hooking them up for another 80-90psi. If you completely deplete your pony then you picked the wrong size for your purposes.

Hi ReefHound,

Yeah, that's pretty much it. I do it a little differently than you described, but close enough.

The first AL80 that I trans-fill from drops to about 2700 psi. The second tops off the pony at around 2900 to 3000 depending on how full the second AL80 is.

So, on the second dive I start with a 2700+ psi tank and finish with about 700 to 1,000 psi. And a full pony.

With my method, I don't have to wait two days for the dive op to fill my pony. I don't have to hear them wailing and gnashing teeth about it. I just do it.

cheers,
markm

 

[Diver-Drex]

Got it. First 80 fills the pony. Second 80 equalizes with the first. All done before the first dive.

I read it as you were topping off the pony with the first 80 in between dives.

 

[caruso]

, I don't have to wait two days for the dive op to fill my pony. I don't have to hear them wailing and gnashing teeth about it.

Not understanding why a Dive Op would give you such a hard time about filling a pony? They always seem to be just fine with it when I ask, although they tell me sometimes they won't be able to get to it before the first morning dive of a trip, so when I fly into FLL I'll swing by Divers Direct on the way out and fill it there.

 

[ReefHound]

Not understanding why a Dive Op would give you such a hard time about filling a pony? They always seem to be just fine with it when I ask, although they tell me sometimes they won't be able to get to it before the first morning dive of a trip, so when I fly into FLL I'll swing by Divers Direct on the way out and fill it there.

Whether it makes sense or not is irrelevant. Sounds like you're talking about Florida - cave country, land of technical divers. What about Cozumel? Most shops don't fill their own tanks, they get them filled at a big island service and delivered each morning. Other places most likely just don't want to be bothered with it, especially when they do not typically fill customer tanks.

 

[Manatee Diver]

Whether it makes sense or not is irrelevant. Sounds like you're talking about Florida - cave country, land of technical divers. What about Cozumel? Most shops don't fill their own tanks, they get them filled at a big island service and delivered each morning. Other places most likely just don't want to be bothered with it, especially when they do not typically fill customer tanks.

Just ask in the Cozumel forum, chances are someone will direct you to a shop with a small compressor, just pay a few bucks and get it filled. Now if you are staying on one of the southern resorts, those operators have compressors on site, just drop it up the afternoon before and it will be filled for the morning.

 

[caruso]

Whether it makes sense or not is irrelevant. Sounds like you're talking about Florida - cave country, land of technical divers. What about Cozumel? Most shops don't fill their own tanks, they get them filled at a big island service and delivered each morning. Other places most likely just don't want to be bothered with it, especially when they do not typically fill customer tanks.

I've brought my pony to Florida, Cozumel, Roatan, Belize, Curacao, and Bonaire and had no issues filling my pony tank. In Cozumel I used Aldora divers, I asked them to fill my tank when I checked in, and they said no problem and even had it brought to the boat although the crew apologized to me that they didn't assemble my rig because they weren't sure how I wanted the pony tank mounted.

When you say "most don't want to be bothered", now that doesn't make sense to me, given that diving is a very customer service oriented sport regardless of where in the world the diving takes place. A Dive Op that can't be bothered providing a needed service to their customers won't be in business very unless they're the only game in town, and in Cozumel there's plenty of competition.

 

[ReefHound]

When you say "most don't want to be bothered", now that doesn't make sense to me, given that diving is a very customer service oriented sport regardless of where in the world the diving takes place. A Dive Op that can't be bothered providing a needed service to their customers won't be in business very unless they're the only game in town, and in Cozumel there's plenty of competition.

Aldora is one of the few with their own compressor, which they bought because they highlight their steel tanks and couldn't get Meridiano to fill them right. Filling a pony is not a service that is needed by 95% of their customers. You can probably find a place to get it done, my point was it's an extra hassle versus being able to transfill yourself in 5 minutes. I don't want to deal with the logistics or making it a part of the search criteria or verifying who can or cannot do it.