Steel 120's

[flyboy08]

Obviously, depend on the depth...

Goes without saying....but down to 80 for a bit then a gradual accent towards 40...typical profile for CZM.

 

[scubadada]

Goes without saying....but down to 80 for a bit then a gradual accent towards 40...typical profile for CZM.

You do your profiles, I do mine

 

[Dave Dillehay]

Somehow we are forgetting the buoyancy advances of hp steel tanks. That is a big deal.

Dave Dillehay

 

[ChuckP]

IMO, I don't really see much of a buoyancy advantage with steel tanks - here that is. You carry 4-5# more with aluminum but I see people over weighted with steel so you really are only a few pounds better in steel - that's here. Because you don't need to carry much weight if at all, the weight of the tank is farther out from your center and some people struggle with that. Guys that dive all the time take full advantage of it and the tank weight out there is nothing, but newer or vacation divers sometimes have issues.

I just looked back thru a bunch of dives and the two differences are average depth and dive time - my average depth with a 120 (65') is pretty consistent 15' deeper than the 80's (50') and it's a rare day I'm under 60 minutes on an aluminum - it's also a rare day that I end a dive with the 120's any less than 1400psi - I could easily dive with the 100's but I like options and honestly, they typically don't let you accumulate the 10-15 minutes of deco that the bottle is capable of giving you.

Tank size is up to the customer, not everyone likes farting around for 45 minutes at 40' after 45 minutes of a normal dive - to each their own. A divers NDL drives the dive plan so it's not like you can just go do Punta Sur beginning to end with the Cathedral and Devils Throat, you have the gas to do it with a 120, but you don't have the NDL - it's a fantastic deco dive though. One thing that's not really said is on the big tank dives, some dives you'll spend 5-10 minutes swimming over sand crossing over to a shallower reef - it's part of it and at times has to be done because you run out of reef. There's nothing wrong with dipping to 80' for 10 minutes and gradually leveling up and doing a 60 minute dive, there's plenty to see. It's all to each their own.

 

[Sloeber]

Hi Henry,

I don't need 120's to make 90 minute dives but some divers do. That's the beauty of having choices. Scuba cylinders are not one size fits all. When divers need more air, we have the tanks available to them. We offer 120 as a rental through Aico and we own 100, 80, 60, and even 40's.

OK, so I have a better than average RMV @ 0.36 cu ft/min. I could do a 1 hour dive at an average depth of 66 ft with an AL80 and surface with just under 500 psi. Are your average divers better than this, are you? Of course, ndl comes into play.

Truthfully I haven't a clue. I suppose if my gas consumption was an issue I'd probably try to analyze it, but its not, so...

 

[Coztick]

I go to Coz. with a non diver wife to meet up with our non diver friends who all stay at the Iberostar.
The southern location and surface intervals back at the resort is very convenient for me. They run timed dives using al80's. While fine for the 50-60min run times at most sites, it would be nice to see more in the Punta Sur area.
I've done about 100 dives with Dressel's and would like to try a longer dive at the south sites.
Of the OP's diving 120's, are any sidemount friendly? I would just take both tanks on both dives for balance.

 

[ChuckP]

I go to Coz. with a non diver wife to meet up with our non diver friends who all stay at the Iberostar.
The southern location and surface intervals back at the resort is very convenient for me. They run timed dives using al80's. While fine for the 50-60min run times at most sites, it would be nice to see more in the Punta Sur area.
I've done about 100 dives with Dressel's and would like to try a longer dive at the south sites.
Of the OP's diving 120's, are any sidemount friendly? I would just take both tanks on both dives for balance.

Sidemounting 120's omg you aren't wearing a drysuit!!! Maybe just take an extra 80 for the day and only breathe 75-1000 outa the first tank, breathe the second tank all the way down and swap out for a new tank for the second dive...... The problems you'll have is you're stuck with the run time of the dive group so you can carry six tanks but if the group has everyone on 80's..........

Your NDL defines your time at depth, bigger tanks just add time in the shallower section of the dive.

 

[Dave Dillehay]

IMO, I don't really see much of a buoyancy advantage with steel tanks - here that is. You carry 4-5# more with aluminum but I see people over weighted with steel so you really are only a few pounds better in steel - that's here. Because you don't need to carry much weight if at all, the weight of the tank is farther out from your center and some people struggle with that. Guys that dive all the time take full advantage of it and the tank weight out there is nothing, but newer or vacation divers sometimes have issues.

I just looked back thru a bunch of dives and the two differences are average depth and dive time - my average depth with a 120 (65') is pretty consistent 15' deeper than the 80's (50') and it's a rare day I'm under 60 minutes on an aluminum - it's also a rare day that I end a dive with the 120's any less than 1400psi - I could easily dive with the 100's but I like options and honestly, they typically don't let you accumulate the 10-15 minutes of deco that the bottle is capable of giving you.

Tank size is up to the customer, not everyone likes farting around for 45 minutes at 40' after 45 minutes of a normal dive - to each their own. A divers NDL drives the dive plan so it's not like you can just go do Punta Sur beginning to end with the Cathedral and Devils Throat, you have the gas to do it with a 120, but you don't have the NDL - it's a fantastic deco dive though. One thing that's not really said is on the big tank dives, some dives you'll spend 5-10 minutes swimming over sand crossing over to a shallower reef - it's part of it and at times has to be done because you run out of reef. There's nothing wrong with dipping to 80' for 10 minutes and gradually leveling up and doing a 60 minute dive, there's plenty to see. It's all to each their own.[/QUOTE

Dear Chuck,

After personally guiding thousands of divers in Cozumel, I found it quite common, especially among newer divers, to get the air our of their BCs and descend—often a struggle. In almost all cases when dealing with our divers, we would normally ask them to take off 4 lbs from their "normal" aluminum 80 weight. But given with the hp tanks that are normally 8 lbs heavier when full—that makes getting down much easier for all. On the other end, with NO bouyancy—what is wrong with that. I have a whole bunch of experience in this and tell you that it does matter to even the average diver.

Dave Dillehay

 

[scubadada]

Choice of cylinder is probably largely dependent on diver experience and expectation. When my son and I dived Coz, we both had a primary computer running DSAT, my backup was a Cochran. We did not want to be shortchanged on the deep portion of the dive, and did not want to be limited on the shallower portion. The Aldora 120s were just fine, we could have done just as well with the 100s, but who knew? Having 4 lbs less weight did not make any difference, but was just fine. Everyone has there own expectations. If I were to return to Cozumel, I would like return to Aldora. My son and I had great dives at Barracuda and San Juan, I would love to dive the more northern sites

 

[Coztick]

Sidemounting 120's omg you aren't wearing a drysuit!!! Maybe just take an extra 80 for the day and only breathe 75-1000 outa the first tank, breathe the second tank all the way down and swap out for a new tank for the second dive...... The problems you'll have is you're stuck with the run time of the dive group so you can carry six tanks but if the group has everyone on 80's..........

Your NDL defines your time at depth, bigger tanks just add time in the shallower section of the dive.

Thanks Chuck,
I carry 4lbs with a single al80 so maybe a little too negative to swim up with 120's?
Al80's would be preferred, I'd pop for a forth 80 for unlimited gas if there is room on the boat.
I get being limited by others, I'm only interested if everyone is using 120's and expecting 90min dives. I certainly wouldn't mind finishing shallow...
Edit...
I guess I'd have to do a checkout dive with a new dive op?