Sidemount Deco Cylinders - top or bottom mounted?

[rjack321]

with all this talk about top mount vs bottom mount has anyone marked their second stages to ID the gas mix? Ive never done it but I remember reading a thread about it and seems it would be fitting if you top mount deco bottles.

For God's sake YES! I mark every bottom stage and deco bottle with the MOD of the gas inside. This has been industry standard instruction for quite a few years now...

Obviously if you top mount them you can't read the MOD unless you remove the rear clip and swing it around in front of you. Bottom mounted tanks (either deco or bottom mix) you should be able to read the MOD. Which is sorta what RN was getting at with this thread.

 

[Teller]

with all this talk about top mount vs bottom mount has anyone marked their second stages to ID the gas mix? Ive never done it but I remember reading a thread about it and seems it would be fitting if you top mount deco bottles.

For God's sake YES! I mark every bottom stage and deco bottle with the MOD of the gas inside. This has been industry standard instruction for quite a few years now...

Obviously if you top mount them you can't read the MOD unless you remove the rear clip and swing it around in front of you. Bottom mounted tanks (either deco or bottom mix) you should be able to read the MOD. Which is sorta what RN was getting at with this thread.

Im not askng if you mark you cylinders, thats an obvious answer. Im asking have you ever marked the second stage of your regulator that is attached to the cylinder needing to be ID during the dive? By doing so you wouldnt have to swing the top mounted cylinder to ID the gas mix you could just look at the second stage.

 

[rjack321]

Im not askng if you mark you cylinders, thats an obvious answer. Im asking have you ever marked the second stage of your regulator that is attached to the cylinder needing to be ID during the dive? By doing so you wouldnt have to swing the top mounted cylinder to ID the gas mix you could just look at the second stage.

Oh gotcha, sorry my misunderstanding.

This has been discussed I don't know how many times before. The label on the cylinder is the only definitive link between the analysis/gas inside and your lungs. Regs get put on the wrong bottles by accident, regs get shared when you or your buddies goes belly up and you end up using a spare etc etc.

 

[Teller]

Im not askng if you mark you cylinders, thats an obvious answer. Im asking have you ever marked the second stage of your regulator that is attached to the cylinder needing to be ID during the dive? By doing so you wouldnt have to swing the top mounted cylinder to ID the gas mix you could just look at the second stage.

Oh gotcha, sorry my misunderstanding.

This has been discussed I don't know how many times before. The label on the cylinder is the only definitive link between the analysis/gas inside and your lungs. Regs get put on the wrong bottles by accident, regs get shared when you or your buddies goes belly up and you end up using a spare etc etc.

I would assume that if you analyze right before you get on the boat, put the reg on the cylinder and then mark the reg that would be just as good as marking the cylinder.

 

[FoxHound]

Im not askng if you mark you cylinders, thats an obvious answer. Im asking have you ever marked the second stage of your regulator that is attached to the cylinder needing to be ID during the dive? By doing so you wouldnt have to swing the top mounted cylinder to ID the gas mix you could just look at the second stage.

This is why I mark the top of the bottle, the bottle itself is still marked and it is in a place that I can still easily see it when the bottle is topped mounted

 

[rjack321]

I would assume that if you analyze right before you get on the boat, put the reg on the cylinder and then mark the reg that would be just as good as marking the cylinder.

I theory, but people mess that up. Good shops won't let you leave without analyzing the cylinder and you quickly realize that the marked MOD doesn't match the contents. Anytime you start using something else to verify, esp. something you made up or marked on the back of the boat etc you are asking for trouble. Do whatever you like but you'll find reams of threads on this topic here and on most other technical boards. This is exactly why RN is bottom mounting his deco bottles, so he can see the MOD and not have it behind him.

 

[Dive-aholic]

For those that replied with top mount your stages, do you mean bottom mix stages or all stages, deco mix included? I'm specifically asking about deco mix stages in this thread. rjack hit is on the head. I've seen a few people top mount their deco cylinders and I'm having a difficult time grasping why.

Here's what I've seen:

Diver picks up deco bottle where it was dropped in the cave, clips it on top, swims 60' until depth is 20' and starts breathing it. No verification of MOD.

Diver picks up deco bottle where it was dropped in the cave, clips it on top, swims 60' until depth is 20' and unclips bottom to verify MOD then reclips.

Diver picks up deco bottle, struggles with trying to get it clipped on top for about 2 minutes, finally gets it in place, breathes it for 3 minutes and exits cavern. Oh, and the deco bottle is position with the bottom of the tank much higher than the tank in the 2nd photo I posted in post 9 earlier.


I don't get the deco bottle on top thing, especially for cave diving. In a cave the bottle doesn't stay with us. We drop it less than 100' inside the cavern. We swim it less than 100' back. We remain motionless (hopefully) while we're doing our decompression stop. Then we swim out of the cave a few feet. So why mount it on top?

 

[Kevrumbo]

MOD sticker and your FO2 analysis sticker for your deco mixes should have the appropriate & corresponding values; on deco gas switch, buddy verifies the MOD (example "21m") from the sticker on the outside middle to bottom of deco bottle --I verify the FO2 from my analysis sticker at the top inside neck/shoulder & under the handwheel/valve of the deco bottle (i.g. simple written designation of "50"). Similarly for the pure O2 deco switch --buddy verifies sticker "OXYGEN 6m", while I verify a written "100" on my analysis sticker. . .

 

[DA Aquamaster]

MOD sticker and your FO2 analysis sticker for your deco mixes should have the appropriate & corresponding values; on deco gas switch, buddy verifies the MOD (example "21m") from the sticker on the outside middle to bottom of deco bottle --I verify the FO2 from my analysis sticker at the top inside neck/shoulder & under the handwheel/valve of the deco bottle (i.g. simple written designation of "50"). Similarly for the pure O2 deco switch --buddy verifies sticker "OXYGEN 6m", while I verify a written "100" on my analysis sticker. . .

I think that's a great approach, one that supports the team concept. However my preference is to overlay that on top of a gas switch protocol that can be done independently.

I don't always encounter ideal conditions in cave diving and the gas switch can conceivably occur in situations where verifying gas and communicating the same can be difficult - for example on very low viz while exiting a silty sidemount cave, while in a very tight passage, or (theoretically) in the situation we all train for and practice in a total lights out/silt out exit.

I believe in verifying my team mates gas during the switch, but I never want to have to rely on it and bottom clipping the tank to enable easier verification of the gas (by feel alone if needed) just makes more sense.

 

[tphelps]

I do back gas on the bottom and then decompression gasses on top of them. I have the regulator side closests towards my mouth with contents label and MOD easily visible. If it is a Tec SM dive, high O2 blends on my right and less on my left (left lean, right rich). Hope that helps!