Aluminum 80s versus larger steel tanks

[krbailey]

I agree with much of what has been said regarding the use of larger and tanks and an increased risk for DCS. I may be wrong, but it is my belief that many of the posters in this thread are not at all characteristic of the average diver in Cozumel. I would also guess that the number of Cozumel divers who could benefit from the use of larger steels, and who could do so with absolutely no increased chance of injury to themselves, are but a small percentage of the total number of Cozumel divers. In my opinion, the vast majority of the divers who travel to Cozumel are "vacation" divers who take one or two excursions a year, and that's all the diving they do. I know divers in Texas who don't dive anywhere else. It makes no sense to me, but that is what they do. I think when this type of diver makes up the majority of a dive op's customer base, diving within NDLs and avoiding DCS hits, etc., have to be real concerns.

As for me, I love my Steel 72.

I'm confused by this statement. I agree that the majority of divers in Cozumel are "vacation divers" who would use larger tanks to extend their bottom times. Even though their bottom times are longer I would think that their SAC rates (typically much higher for the average "vacation" diver) would keep them from approaching NDL's. I base this on the assumption that an occasional diver would have greater than 1.5x the SAC rate of an experienced diver which would more than offset the 50% larger tank capacity (the SAC rate comparison is just a guess on my part based on my own experience as a vacation diver). On the flip side, an experienced diver with a low SAC rate could definitely exceed NDL's with a larger capacity tank. Hopefully, their experience would make them more aware of this limitation and plan their dives accordingly.

 

[cvchief]

Hey Chief, is this a challenge? If so, my longest as a dive guide with paying clients was at Paso De Cedral, ending in San Francisco—2 hours 2 minutes, max depth 55 ft but multi level following our Oceanic computers. It was I that ended up calling the dive as I was OOA!. However time of a dive means nothing unless depth and profile are considered. But it is not reasonably questioned that more air can provide more dive time.

Dave Dillehay
Aldora Divers

PS You still in town? When are we going to get that Margarita?

well no. I imagine I can't beat you. I will however offer the missus as a stand in. She'll run you to 0. Of course for 2 hours I will have to buy her a suit wamer or a dry suit.

And I am leaving tomorrow. Be at kondessa around 7 tonight. Why don't you come by? I txted the number memo gave me. Couple times but you didn't answer. He has my cell in his txt messages. I love to meet you in person.

 

[Ron Lee]

I love to meet you in person.

You cannot fully appreciate Dave until you go on a dive with him. Just do it.

 

[cvchief]

You cannot fully appreciate Dave until you go on a dive with him. Just do it.

I emailed, PM, texted, etc. I think he is playing hard to get.... I could have used some help with the margarita bill too...

 

[Lorenzoid]

I'm confused by this statement. I agree that the majority of divers in Cozumel are "vacation divers" who would use larger tanks to extend their bottom times. Even though their bottom times are longer I would think that their SAC rates (typically much higher for the average "vacation" diver) would keep them from approaching NDL's. I base this on the assumption that an occasional diver would have greater than 1.5x the SAC rate of an experienced diver which would more than offset the 50% larger tank capacity (the SAC rate comparison is just a guess on my part based on my own experience as a vacation diver). On the flip side, an experienced diver with a low SAC rate could definitely exceed NDL's with a larger capacity tank. Hopefully, their experience would make them more aware of this limitation and plan their dives accordingly.

That sounds like a lot of speculation to me. I would imagine there are inexperienced divers who because of a small body size have low SAC rates. Who knows what tank capacity would "offset" what SAC rate assumptions. All I know is that it seems reasonable to me that a lot of dive ops might be perfectly content to continue using Al 80s in part as a constraint on the inexperienced divers who might make up a large part of their clientele. An Al 80 is what those divers are familiar and comfortable with, they "get" the bit about being back on the boat "when your gauge reads 500 PSI," etc.

 

[boulderjohn]

I certainly don't know more than a small fraction of the dive operations in Cozumel that offer higher capacity tanks, but I have used three of them. All three tend to attract more of the highly experienced divers than beginners. That is, in fact, the reason I used each of them.

 

[cvchief]

I certainly don't know more than a small fraction of the dive operations in Cozumel that offer higher capacity tanks, but I have used three of them. All three tend to attract more of the highly experienced divers than beginners. That is, in fact, the reason I used each of them.

Er, isn't three all of them? I mean for the bigger than 100 AL tanks.

 

[Sideways]

No brainer for me. I prefer HP 120 Nitrox. Nice long bottom times with no deco worries. Just got back and loved using them this trip!

 

[scubafanatic]

So, 300+ posts so far, and nobody has yet discovered the obvious, so I'll chime in:

The dive 'market' in Cozumel is 'mature' and an equilibrium has been established, meaning there's just enough interest in steel tank ops to feed the existing 3 steel tank operations, there's no danger of a sudden giant expansion in the size or number of steel tank ops, the free market has already set a 'cap' beyond which more steel tank 'supply' isn't needed. (for what it's worth, I prefer steel too, owning 17 steels)

AL 80's are much cheaper to purchase, and last much longer than steels if subjected to 'abuse'. (Dave @ Aldora confirmed he owns/fills his own steels to reduce tank filler 'abuse' to extend tank life, and even then he gets only 5 yrs operational life from his steels.)

AL 80's enable dive ops to cycle through/mass-produce 'dive units' (dive unit = 1 paid dive) a lot faster, as the dives are substantially shorter vs steel tanks under the same dive conditions. So clearly, dive ops (if not the dive customers) certainly have a strong incentive to pump out lots of shorter dive vs fewer longer dives.

It's bizarre to hear some divers say they prefer shorter dives as they'd get bored on longer dives, 2 90 min dives = same dive time as 3 60 min dives ! How does splitting dive time into shorter slices make dives more interesting ???
If you dive say, Santa Rosa today for 60 min in your AL 80, then on another day do a 2nd dive on Santa Rosa in your AL 80 for 60 min, well, you've just dove Santa Rosa for 120 min total! How would that be defined as NOT boring, but my single 90 min dive/steel tank be defined AS boring ???

Shorter dives are a pain in the ass, you've got to gear up/gear down more often, schlep gear around more = higher % of vacation time spent preparing to dive vs just diving !

IMHO, the biggest DCS initiator are yo-yo profiles, especially with short surface intervals, which is what you get doing more short dives vs fewer longer dives. In Cozumel I've experienced compressed SI's that were really pushing the limits, because the dive ops are trying to cycle divers through ASAP, which is one reason I dive NITROX on all Cozumel dives,

 

[DjDiverDan]

When my Nephew warned me that the Zombie Apocalypse was coming, I never expected that it would first appear on a Scuba Board Post. Will this thread never die?