First Deco Bottle

[Clammy]

Hi, I was wondering what a good first deco bottle would be? We're not talking long decos, just simple stuff where maybe 10-15 minutes of deco with nitrox at shallow depths are required. Al40?, 73, 80? those are my choices at the moment. I mean I know the 40 will be sufficient but should I go with larger tanks just to get used to it?

[wedivebc]

Hi, I was wondering what a good first deco bottle would be? We're not talking long decos, just simple stuff where maybe 10-15 minutes of deco with nitrox at shallow depths are required. Al40?, 73, 80? those are my choices at the moment. I mean I know the 40 will be sufficient but should I go with larger tanks just to get used to it?

40 is plenty for short deco but be awaare deco diving is very addictive so don't stash that 80 too far away either.

[DA Aquamaster]

I am a big fan of the Hymark Aluminum 72. Almost the same capacity as an AL 80 but a few pounds lighter, only 6.9 inches in diameter and neutral with about 500 psi in it, so it does not get all floaty like and AL 80.

I also like LP 45's for O2.

[ivobj]

If only one, I would go for the AL80, because although the 40 is enough for the dives you do now, as you progress you tend to do longer decos and very soon the 40 won't be enough, leave it for the second one, with 2 bottles you can use the 40 only for O2 at 6 mt

[rjack321]

AL40
Do not get the biggest to "get used to it". Learn on the smaller easier bottle then add larger/bulkier cylinders once you are proficient. Build on success.

2x AL40s are enough for even 180-200ft dives, so its not like they are training bottles that have limited utility down the road. They are very useful, in fact I have 6 of them (in addition to a whole bunch of al80s).

[liuk3]

If I were you, I might look into getting some formal training before buying the equipment...

[Clammy]

If you were me, you'd know that it's scheduled. The equipment is for a group buy, considering buying with.

[liuk3]

What class are you taking? I would probably ask your instructor which size would be appropriate.

[jscott099]

A 40 is the max recommended for TDI Advanced Nitrox, and Decompression Procedures with a 30 as the minumum. O2 reg on DIN with 6" SPG. In extended Range you will need two deco bottles, 30 or 40.

[DA Aquamaster]

I agree that going big is not ideal. An AL 80 is overkill as a strictly deco bottle, although some divers like them for the ability to use one bottle on the whole trip, where a 40 may need to be filled every 2-3 dives.

Personally, in a cave environment, I prefer a 30-45 sized tank for deco - it is easier to get into and out of caves where there may be a high flow entrance, there is no confusing it with an AL 80 or AL 72 stage bottle, and it is a lot less bulky when stacked with a stage bottle on the way in or out. Having lots of really large bottles apparently looks cool and studdly but it is in reality just a pain if you don't have a real reason to do it.

Technical diving is not something where gearing up for the deepest dive you ever plan to make
really works all that well on the other 90% of the dives you do and if you start diving deep enough where you need a 77 cu ft deco bottle, the cost of the AL 80 is pocket change.

In most north Florida caves, O2 is the primary deco gas and unless you go crazy with the bottom times, a 40 or 45 will provide enough for at least 2 and sometimes 3 dives with a 50% reserve on the last dive.

I am just now getting rid of my AL 30's as my deco profiles have gotten to the point where they only have enough capacity for one dive with an adequate reserve, but they served me well for years and are light and compact, so if you anticipate only short deco in the 20 minute range on O2 an AL 30 is not a bad option either and they will help you keep the total weight carried down a bit.

I have a few AL80's rigged as stages, and with 32% they work well in N Fl caves as stages, and also work well as travel gas and deco bottles on trimix dives in the 200' range. With bottom mix, they can also serve as a stage on a trimix dive (but are annoyingly floaty when empty), and obviously as noted above they could hold enough O2 for a few days of deco diving, so they are very versatile. But they are also my least used tank as I prefer the LP 45's for deco and the the AL72 for a stage or as a buddy/bailout bottle as it swims and handles better than an AL 80. The AL 72 is becoming popular with rebreather divers who need more bailout gas than a 40 or 45 allows, but where carrying an AL 80 is a PITA.

An AL 80 also puts you at a disadvantage on a deeper / longer deco dive if it is your only deco bottle from two points of view:

1. In an ocean dive if you have significant deco it makes sense to get on a deco gas earlier 50% at 70 ft as a first deco gas rather than waiting to get to 20' to go on O2. 50% is an ok compromise if you only have a single gas, but it makes more sense to split the gas into two 40's, one with 50% and the other with 100% on most deeper / longer deco dives with nitrox. Using a much larger AL 80 for the first deco gas with O2 percentages in 30-36% range at an initial stop of 120-130 ft begins to make sense when you finally get into trimix dives, but is mostly overkill until then.

2. From a lost gas planning point of view, two deco bottles make more sense as the unavailability of either still leaves you one deco gas and your back gas, rather than just your back gas to complete the deco. And it leaves you with two deco regs so that potentially you could move the reg from once deco gas to the other as you ascend in the event one of the deco regs fails - although I'd only be tempted to do that in the even the reg on the higher percentage deco gas failed. Flooding the high percentage reg to access the deeper deco gas, could leave you with no deco gas, so a lost gas contingency plan makes more sense if the deep reg fails.

[ianr33]

Get a 40.

If you will be using 50% for deco it holds enough deco gas for "light" deco dives.

Down the road maybe use it for an O2 bottle. A 40 of O2 is enough for almost any dive.

And dont worry too much about what is the "best" tank to buy. If you get into this addiction you will end up with a garage full of tanks anyway!:D

[Clammy]

What class are you taking? I would probably ask your instructor which size would be appropriate.

Fundies and I'm supposed to take Deco 1 and adv nitrox which was supposed to be in May, now tentatively August (time conflicts). I"m not sure if fundies and taking deco 1 and adv nitrox outside the GUE course conflicts or not. I guess I'll find out.



Wow, I expected just a few responses! Thanks for the input!

[ianr33]

Whats "Deco 1" ?

[Clammy]

Whats "Deco 1" ?

"Decompression Procedures Diver" through TDI

Just been calling Deco 1.

[liuk3]

Fundies and I'm supposed to take Deco 1 and adv nitrox which was supposed to be in May, now tentatively August (time conflicts). I"m not sure if fundies and taking deco 1 and adv nitrox outside the GUE course conflicts or not. I guess I'll find out.



Wow, I expected just a few responses! Thanks for the input!

Pretty cool. I believe the AL40 is what you're looking for. Sounds like you are diving hard and having fun!

[Clammy]

Yup! Time and money being the limitations!! Argh!! Gear... training... or trips... I get to pick 1 at a time =/

[JeffG]

Luxfer Alum 40 to be specific.

[Clammy]

Luxfer Alum 40 to be specific.

What about a hymark 40? I'm told they are pretty much the same as luxfers.

[rjack321]

What about a hymark 40? I'm told they are pretty much the same as luxfers.

Luxfer's are no longer available. The Hymarks have a slightly different neck shape but are otherwise identical in behavior to the Luxfer's.

[JeffG]

Luxfer's are no longer available.
Really? Since when? I've never heard that. (but then again...I haven't shopped for a tank in years)


They still list them on their website

http://www.luxfercylinders.com/products/scuba/specifications/us_imperial.shtml

[rjack321]

Fundies and I'm supposed to take Deco 1 and adv nitrox which was supposed to be in May, now tentatively August (time conflicts). I"m not sure if fundies and taking deco 1 and adv nitrox outside the GUE course conflicts or not. I guess I'll find out.

GUE doesn't care if you chose to go onto some other course after GUE-F. Although if you are somehow thinking this TDI Deco 1 course will help you prepare for eventually taking GUE Tech 1, I would counsel against that. It will probably just build some different habits you might need to unlearn.

[rjack321]

Really? Since when? I've never heard that. (but then again...I haven't shopped for a tank in years)

Luxfer stopped making scuba tanks around the end of 2008. TDL among other places have basically blown out their old stock. The Hymark's seem to be equivelant. To save a machining step, the neck isn't turned down on a lathe like the Luxfer's so there's slightly more metal around the neck. Buoyancy wise I can't tell them apart tho. I have 4 Luxfers, and 2 Hymarks.

[Clammy]

GUE doesn't care if you chose to go onto some other course after GUE-F. Although if you are somehow thinking this TDI Deco 1 course will help you prepare for eventually taking GUE Tech 1, I would counsel against that. It will probably just build some different habits you might need to unlearn.

Fundies is coming first for me.

[JeffG]

Luxfer stopped making scuba tanks around the end of 2008.

I can't seem to find any evidence of this. FWIW

[Blackwood]

I can seem to find any evidence of this. FWIW

I heard the same thing (about them stopping production of scuba cylinders) and bought a handful of extra 40s last year. Since then I've heard that they're stopping production of SOME of their scuba cylinders, but will continue making the best sellers (including Al40 and Al80).

I can't verify this. Just what I've heard.

[rjack321]

I can seem to find any evidence of this. FWIW

While Luxfer seems to have been caggy about what exactly is going on, its definitely hard to find a Luxfer 40 at shops or online for now. They may or may not be manufacturing, but Luxfer seems to not be shipping anything out at least for now

The Hymarks are readily available and seem to work fine.

[Bismark]

GUE doesn't care if you chose to go onto some other course after GUE-F. Although if you are somehow thinking this TDI Deco 1 course will help you prepare for eventually taking GUE Tech 1, I would counsel against that. It will probably just build some different habits you might need to unlearn.


Agree with Richard on this one. My guess is after you complete a GUE course you will most likely want to continue in that line. I would suggest saving some of your hard earned money and apply it to your GUE Tech I when you feel you are ready and comfortable to do so. You also get trimix training with the GUE class.

[DA Aquamaster]

Blackwood is closer to the truth. My understanding is that Luxfer has scaled production of scuba cylinders way back and will in essence make the occasional run of scuba tanks (probably AL 80's) when the demand warrants it. I would not bet on AL 40's being available to the same degree they have in the past - at least from Luxfer.

Hymark however has entered the market with some excellent tanks in AL80, AL72 and AL 40 sizes so Luxfer will not be missed.

[NorthWoodsDiver]

Hi, I was wondering what a good first deco bottle would be? We're not talking long decos, just simple stuff where maybe 10-15 minutes of deco with nitrox at shallow depths are required. Al40?, 73, 80? those are my choices at the moment. I mean I know the 40 will be sufficient but should I go with larger tanks just to get used to it?

It was suggested to me that I get a 40 for my ADV nitrox/deco class but its hard for me to get good fills because I partial pressure blend my nitrox so I really wish I had got an 80 or a 72 for my 40-50% tank instead of an aluminum 40. Then I could get 2 good dives off a tank with a comfy reserve. I have lots of aluminum 80's around and they are easy to come by used but I haven't taken the time to O2 clean them yet. If you have to buy a tank specifically for this use I would suggest the 72's or 80's.

For 100% O2 a 40 is fine but I still only get one dive off it or sometimes 2 short ones, simply because I can only fill to 2200psi or so.

[DA Aquamaster]

That is one of the advantages of an LP 45 over an AL 40. It still has a decent capacity even if only partially filled to the 2000-2200 psi range and you can get much better partial pressure fills with the lower 2400 psi service pressure.

Plus, many shops either lack the ability to do a 3000 psi O2 fill or are unwilling to do so, due to the high pressure. So for an O2 bottle an LP 45 makes a lot of sense. At 2200 psi an LP 45 will still hold 37 cu ft compared to 29 for an AL 40. An AL 80 will hold 56 cu ft at that same pressure, but it is much larger and harder to handle especially when you consider that it is 4.4 lbs buoyant when empty, so it is essentially a buoyant tank when you start out at only 56 cu ft.

The bad news is that LP 45's are hard to find and cost about twice as much as an AL 40.

[willardj]

I like to use steel 72(100%) or an al 80(80%) for Deco if useing a single gas. I have plenty of them and didn't have to buy any more tanks. The 40's are easier to carry, but it didn't take much extra time in the water to get use to the 80's. The best thing about them is you can go just about a whole trip on 1 fill.

[Empty V]

I suggest not buying anything until you get through fundies. Wait until you actually book a class that requires it and get what the instructor recommends.

Billy

[Rainer]

I suggest not buying anything until you get through fundies. Wait until you actually book a class that requires it and get what the instructor recommends.

Billy

Totally agree with the above. For all you know, it could be quite some time before you find yourself ready for a tech class. By then, who knows what deals you might find on cylinders (used or new). To buy now, only to have it sit in your garage seems like a misuse of funds that could be better spent. Your money, though, so do as you please.