What is a deco bottle?

[Cave Diver]

Okay, I can see that.

I guess my question is for people doing extended deco dives using multiple gasses, do you have a computer or just bottom timers?

Seriously, trimix computers are really expensive.

Cut tables using planning software, including contingency for +/- runtimes, +/- depth, lost deco gas. Mixed gas computer as backup, or set to gauge mode.

On CCR, using mixed gas computer (VR3) set to constant PO2 with bailout tables for mixed bailout gasses in the event of failure.

 

[H2Andy]

I guess why buy the $1600 computer?

It seems that tool, 'expensive computer', is not really being utilized.

yeah well i figured that out AFTER i'd bought my NitekHe



i got mine used for under $400 though ... so ... not too much pain there. it's still a sweet computer for non-deco diving

 

[syntaxerrorsix]

Aside from the dead battery thing, but that is what a backup computer is for.

I totally understand what you are saying.

You need to plan the dive to make sure your bases are covered, i.e. you've got the gas for the dive.

To me, I would plan the dive, make sure I've got the appropriate gas for the dive I want to do, but use the computer for the dive.

I know deco adds up quickly, but if you end up not diving as deep as planed your plan is going to be overly conservative and your computer will do the real time math for you and reflect this.

From the tec guys I've talked to they plan out their dive, write their dives on their slates or whatever, pop on the bottom timer and the $1600 multiple gas computer and off they go and really only dive the bottom timer.

I guess why buy the $1600 computer?

It seems that tool, 'expensive computer', is not really being utilized.

The computer logs the dive at every event. That's its greatest utility. It can also generally get you out of the water faster because you can set the conservation factor lowering than the tables you are using and it isn't based on a square profile. This can come in handy in a couple of different scenarios. Other good features like monitoring po2 daily limits (automatically as opposed to adding it up yourself) on multiple dives and monitoring partial pressure can come in handy when using different mixes. Just my thoughts on it.

It's another available tool to the diver that doesn't get confused or narced and has certainly found it's place on the wrists of all types of divers.

 

[HowardE]

Aside from the dead battery thing, but that is what a backup computer is for.

I totally understand what you are saying.

You need to plan the dive to make sure your bases are covered, i.e. you've got the gas for the dive.

To me, I would plan the dive, make sure I've got the appropriate gas for the dive I want to do, but use the computer for the dive.

I know deco adds up quickly, but if you end up not diving as deep as planed your plan is going to be overly conservative and your computer will do the real time math for you and reflect this.

From the tec guys I've talked to they plan out their dive, write their dives on their slates or whatever, pop on the bottom timer and the $1600 multiple gas computer and off they go and really only dive the bottom timer.

I guess why buy the $1600 computer?

It seems that tool, 'expensive computer', is not really being utilized.

When I do OC Deco dives... I dive my computer which is a Shearwater Pursuit. I also have a backup computer which depending on what gas I'm diving, I either use in gauge mode, or keep it in dive mode - just to see what it does.

I also cut tables using MV Plan (which is freeware, and uses Gradient Factors like my Pursuit) and carry those with me. Printed out, and laminated (yeah... I have a laminator)

The Table (Plan) for me is an outline, and a backup. The computer IS my plan. If I dive with a buddy... We agree to dive the most conservative profile (computer assigned stops).

----

When I'm diving CCR. I do the same thing, but I use the Evolution's on board computer (Vision) and use the Shearwater as a backup. Also - I run some numbers to see what my profile would look like.

 

[ligersandtions]

To go along with the original question....is there a difference between a "stage bottle" and a "deco bottle"? Or are these the same things with different names??

 

[TSandM]

I pre-plan my deco dives, but I'm happy to have my X1 with me in caves, where the profiles can be very strange, and figuring ones average depth can get challenging. The X1 gives me a reality check.

Edited to add: The difference between a stage bottle and a deco bottle is what's in it, and when it's used. Stages have bottom mix in them (whatever you are going to breathe during the major portion of the dive) and are used to extend bottom time. Deco bottles have something other than bottom mix in them and are used for accelerating decompression. Sometimes deco bottles are small (40 cf) as opposed to stages, which are almost always at least Al80s.

 

[MXGratefulDiver]

To go along with the original question....is there a difference between a "stage bottle" and a "deco bottle"? Or are these the same things with different names??

They are ... or can be ... the same things with different purposes.

A stage bottle will generally contain the same mix as you are using for bottom gas. Or on very deep dives, it might contain an intermediate mix used to get you from the surface to a certain depth where a very hypoxic bottom mix is safe to breathe. The purpose of this bottle is to give you adequate gas reserves to do a dive of a particular length or to a particular depth. People will generally use AL80's for stages ... or perhaps even something larger.

A deco bottle will contain a much higher EAN mix ... up to and including 100% oxygen. The purpose of this gas is to shorten the amount of time you must spend at a certain depth, or between certain depths by enhancing the offgassing process (as Rick described earlier). Deco bottles will generally be AL80's or AL40's, and will be PROMINENTLY marked as to their contents (since it would be very dangerous to breathe this gas below a given depth, depending on the mix in the bottle).

Both deco bottles and stage bottles will be rigged similarly, as they are intended to be carried in the same way (in my case, clipped to my left shoulder D-ring and to my left waistbelt D-ring).

Depending on the type of diving you're doing, they will also be used differently. In a cave, both stage and deco bottles will be left at certain points in your route, where they can be picked up and used as needed. This is because you will be coming out the same way you went in. In open ocean or wreck diving, you will carry them with you, as there is a high likelihood for exiting from a different point than the way you entered.

... Bob (Grateful Diver)