Bottles

[DeepDiverBob]

What are the recommended size for stage and deco bottles? I am getting a AL80 and hopefully a ST72, and I am trying to find the best use for them. If I need to add more, (okay, when I add more) I will do that as well.

Thanks in advance

[nitroxbabe]

I s'pose it all depends on what you're planning on diving and your gas consumption, doesn't it?

80 & 72 CF bottles are pretty big. I wouldn't want to haul those around unless I really needed that much gas, and I can't imagine a cold-water dive I might do where I wouldn't freeze to death if I stayed down long enough to need that much deco. Since we here in the midwest don't live near any warm water, and it's not practical to fly with bottles, I don't know why you'd need such big bottles.

Also, I wouldn't want that large of an AL bottle hanging off of me. The buoyancy kind of bites, ya know.

I have a cute little 40 CF bottle that I am currently using for deco. So far it's been more than adequate due to time and cold factors.

If you're talking about just staging these and coming back for them later, that's a whole other discussion. I personally think that planning a dive that requires gas that you don't actually have on your person isn't a great idea.

[ppo2_diver]

Size of deco bottles is determined by the dive being done. I have found that for an average 150 foot dive, an AL40 with 50% is more than enough. Sometimes I'll use an AL30. If I'm doing multiple dives per day, I might use an AL80 for 50%. That way I don't have to haul multiple deco bottles on a boat. Do you have a place that can boost O2? If not, the most you'll get out of a T bottle is roughly 2200psi. In an AL80, that will be around half the tank.

DJ

[reefraff]

I'm not a fan of the steel 72's - they used to be the standard but that was back in the days of horse collars and double-hosed regulators. They're heavier, highly negative, quite a bit more expensive and the corrosion problem is a much greater threat than with an aluminum tank.

These days, aluminum 40's and 80's are the tanks to use. The Luxfer S040 and S080 (not the N080) are as good as it gets for trim and bouyancy characteristics and easy enough for everyone to acquire to allow standardization. Smaller than 40 and what's the point, larger than 80 and they're hard to manage.

Carla's point about the gas/time ratio is valid, but she's a girl and everybody knows they're not endothermic which results in short bottom times and unnaturally low SAC rates. ;) Sometimes it can be a judgment call whether or not to add multiple gas switches/bottles, sometimes a safe and effective plan requires it. A 150' dive is normally done with a single deco bottle of EAN50 or TMX50/30. Whether that deco bottle is a 40 or an 80 will be determined by your BT and SAC - for me, more than about 15 minutes at that depth means I need an 80. On deeper dives it is hard to get clean without adding multiple gas switches/bottles and often one, if not all, of them will need to be an 80.

I'll almost always opt for one long dive instead of two shorter ones, but Duane has a good point: I'd rather lug a single 80cf tank along for two short dives than have to hump two 40's back and forth from the boat.

[nitroxbabe]

Carla's point about the gas/time ratio is valid, but she's a girl and everybody knows they're not endothermic which results in short bottom times and unnaturally low SAC rates. ;)

Cold-blooded critters such as myself do not require as much O2 to spark our rather sluggish, reptile-like metabolisms. :)

Ain't ya jealous as you haul that big ol' 80 deco bottle? If I got myself some heated undies I'd be unstoppable.

[SLIM]

You aer asking a question that can give you many answers as you have already found. What is the dive plan and what are the gasses being used. Why are the extra tanks needed? See there is still more I could ask for. If it was just for 1 deco gas then a 40al or a 45s is nice. If you are doing deep long dives then you may need more then just 2 gas switces. I personally like to use a 45s(100% due to the shorter deco then what i get up here) in FL but when doing the long deep dives up here and i use 50% and 100% I use a 80al for 50% ( so I can use it on several dives) and a 72st with 100% (for added weight at the end with seferal lighter stages). If I am going to do a short dive but still have deco I have a 40al to use with 100%. I base tanks to use as to what the dive plan is. If I were to only get 2 tanks to use for DECO then the 40al is nice to keep 50% in and a 45st is great for 10%. Just remember. What can you afford? Is it best to wait a few months longer? Can you dive with that size and does it work for YOU. I know some that only use 80al and 72s. That way what ever is left in the 80 it is easy to top off for a EANx dive but then we have like another 20 tanks to choose from and keep rotating around.

SLIM

[theskull]

The al40 is a very comfortable bottle to dive with, but except for O2 it is a single dive stage. An al80 filled with EAN32 or EAN50 will last for 2 or maybe even 3 dives before needing a refill if used as a deco bottle. And if the stage is truly a stage bottle for lengthening the dive, or for making the dive on and saving all your backgas for a second dive, then the al40 is practically useless--need the al80 for that purpose.

Steel 45 or 72 is the norm for O2 unless you have access to a booster, because it is rare to get more than a 2000 psi fill of O2, and that is still a decent amount of gas in a LP steel tank.

The other issue is accessibility of fills. If you are going cave diving in a remote location, such as Cannonball or Roubidoux, and plan to dive for multiple days you have to bring all your gas with you or drive back home between days. Another vote for the larger al80 bottles and steel 45 or 72.

theskull

[decodiva]

I say get a free one or ones or which ever is the cheapest--
I do believe that is the best way to go.

[CaptnDale]

I use aluminum 40's for most dives. They are easy to carry and hold enough for 90% of my dives. Smaller bottles, such as 30's, are just as bulky to carry as 40's. If I need to carry larger bottles I use 80's. I will only use aluminum bottles for deco's because they are close to neutrally buoyant. I will nearly always take them off and "stage" them on wreck dives. Using bottles that are neutrally buoyant means that I can stage them or retrieve them quickly, "on the fly," without having to adjust my buoyancy much. If you are doing technical diving you should have several deco bottles. They are cheap compared to the other expenses in this sport. I have, perhaps, a half dozen 40's. I can quickly put any of the 80's I use for recreational training into service as a deco bottle when needed.

[ppo2_diver]

Sorry to hijack the thread.

Dale, when are you going to get your charter schedule posted? A few of us would like to do the Rosinco a couple of times this year.

Duane

[CaptnDale]

Sorry to hijack the thread.

Dale, when are you going to get your charter schedule posted? A few of us would like to do the Rosinco a couple of times this year.

Duane

I will have the schedule on the web site in a few days. It is open right now. Only a few dates are spoken for right now. We will probably go back in the water early in March. We have a commercial job that will take us up to Two Rivers in May for a week or two but the exact dates have not been set yet, so May is a bit of a question right now. Otherwise, if you have a day in mind for a Rosinco dive, let me know and I'll put it on the schedule.