deco bottle placement

[Scubydoo713]

When diving with 2 deco bottles (50% and 100%), I was taught that they were both to be carried on the left side, with the richest mix on the inside. Since I have purchased a new low profile mask that has a very limiting field of vision, I find it difficult to see the neck of my bottles. Also, with both bottles clipped to the same D ring, it makes for a crowded area. I have begun to question the safety of this practice. I use different regs on each bottle and don't have a problem confusing the 2 but wonder if seperating them would be safer. In my course book on trimix diving (TDI), the section on gear configuration talks about stages on both sides, the lean mix being carried on the left and rich on the right, although we were taught different. All the divers I dive with carry both stages on the left, although my dive buddy said that if I decided to change, he would too.

I have been seriously considering switching to the left lean, right rich approach. My initial thought was that by putting a stage on the right, it might interfere with the deployment of the long hose in an emergency, but if it was safer for me, wouldn't that be an overriding factor? Also, I have switched to a Greenforce HID canister light that is small and would not be in the way of a stage bottle. Even if it were, it could be moved to the backplate.

I have been diving 2 stages for about 2 years now and this is not something that I take lightly. If I decide to switch, it will be done over the winter in the quarry, where I can dive shallow until I get used to the new configuration.

I would appreciate input from experienced trimix divers on whether you think switching to the left/lean, right/rich configuration is a good idea or not, and why.

Thanks for any help you guys/gals can offer. Jack

Dive safe! Dive often!

 

[Kevrumbo]

Look at the Deco Bottle you're going to switch to. Grab it and pull it up to your face to read it; if you have to, take your time, unclip the the tail and swing it around, read the MOD Sticker near the neck. In all cases, your Buddy should be verifying your Deco Mix for the Depth you're at before you breath it.

Bilateral placement of Deco/Stage Bottles not only affects long hose deployment, but also that right side bottle will hang down in the prop wash of a Scooter and have a negative effect on streamlining (bluff body/pressure drag).

 

[karstdvr]

The deco gas placement should be consistent,and something you'll always do so you develop a habit. I know quite a few people who do what you are talking about,and this is not a problem,as long as you always do it that way. You haven't mentioned what sized cylinders you are using-if they are 40s then they won't interfere with deployment of the long hose,an 80 can be a little more complicating.

 

[mattroz]

why not just switch masks? obviously the being able to see and safely use your deco bottles is much more important than a low profile mask

 

[Scubydoo713]

Look at the Deco Bottle you're going to switch to. Grab it and pull it up to your face to read it; if you have to, take your time, unclip the the tail and swing it around, read the MOD Sticker near the neck. In all cases, your Buddy should be verifying your Deco Mix for the Depth you're at before you breath it.

Bilateral placement of Deco/Stage Bottles not only affects long hose deployment, but also that right side bottle will hang down in the prop wash of a Scooter and have a negative effect on streamlining (bluff body/pressure drag).

My buddy and I always verify each others deco mix, but with both bottles on the same side, it makes it harder, IMO to do than if they were on opposite sides. I hadn't thought about the scooter aspect, and that's a good point, but since I don't scooter and have no intention of buying a scooter, that becomes a non-issue.

The bottles I use for deco are Al 40's by the way, since karstdvr asked and I'm sure that would make a difference if I was using Al 80's. Simply buying another mask as suggested by Mattroz doesn't address the real issue here, which is, why have both bottles on the same side in the first place, where there is more of a chance to use the wrong bottle. Regardless of whether I can't see the neck of the bottles because of limited vision caused by the mask or by extremely low visibility, being able to use all my gear safely and properly is something that I should be able to do with my eyes closed and it just seems like it might be easier if the bottles were on different D rings.

 

[Scared Silly]

I disagree about having both bottles on the same side and a greater chance for error. Perhaps error for getting the right mix but then think about your system as whole. But does puttting bottles on each side introduce other problems? As already mentioned the long hose deployment ans scooter are always the first issues that comes up.

I have done the lean left, rich right. I did not like it very much because it restricted both arms too much which made it hard for me to have at least one hand to adjust fins, dry suit ankle straps, deploy a lift bag/marker, etc.

I have to agree with Matt about the mask. I would look at it as an issue as well. But perhaps not as a end all to the problem at hand. If there is a mask the gives you better FOV would this not be better? Sure during SOP one can get used to having a limited FOV but what about when it is SNAFU? Wouldn't want as much of FOV as possible to help sort out the situation?

 

[TheRedHead]

Look at the Deco Bottle you're going to switch to. Grab it and pull it up to your face to read it; if you have to, take your time, unclip the the tail and swing it around, read the MOD Sticker near the neck. In all cases, your Buddy should be verifying your Deco Mix for the Depth you're at before you breath it..

If you have the MOD on the tank with 4 inch letters, it is pretty easy to see. Combine that with tracing the regulator back to the tank AND having your buddy verify it, makes it a no-brainer. GUE definitely has the right idea about deco bottles.

 

[GDI]

Thuis always a good argument. Bottom line is that the diver needs to do what works best for them and offers the safest way for them to work and move during a dive.

First: The buddy able to read the gas mix and verify the gas for you is yes a good point. Your cylinders do need to be marked so that all divers who come around you can read the cylinder as to it's MOD etc and if required prevent you from making a mistake. However YOU are altimatley responsible for your own safety. If you cannot identify the gas of the cylinder you are about to breath then you are not as safe as you should be. A diver should not have to think much about which way they need to go to get the gas they need to breathe, this skill should be a first natured response.

Example if I came to you and asked you what time it is and all you had to do was tilt your wrist to look at your watch then read the time this would be a first natured response conditioned by consistancy and practise of repeated skill. You don't need to think where your watch is to give me the time,you read it automatically knowing where it is.

You need to look at any skill you do as a solo resolve, you should never rely on a buddy to assist you.

" Diving should be conducted as a solo responsibility carried out as a social activity"

Second:The Long Hose deployment problem concern. Yes there could be a problem if you wrap the long hose around the canister and the cylinder is mounted on the right D ring. Try moving the long hose off the cannister, mount the cylinder on a right shoulder and hip D rings and then mount the other cylinder on the left D rings. Now wrap you long hose behind your right shoulder blade under the armpit and on top off and over the clips of the cylinders, under the left armpit and behind the left shoulder, behind the neck and around to your mouth, now breathe. Deploying it is not all that difficult as it is on top of everything. Grab the second stage drop your head and slide the long hose forward, When the other diver who needs it gets it, slide your hand down the entire length of hose to make sure it deploys to full length. Nothing different here then what you should be doing if it was around your cannister. Oh and before your dive buddy needing air takes full control of the long hose check your left post to make sure your valve is open to be certain that you have air from your short hose reg.

Third. Safer less chance of gas confusion. This is true (Think of the watch example as stated above) as long as you are consistant as to how you rig each and every time, Lean to the left, rich to the right whatever and however you choose - be consistant. The dive team should be similar, but again YOU are sololy responsible for YOURSELF. If you condition yourself to dive this way then you will make things safer for YOU. Your buddy can still do all cylinders to the left as along as you conduct your S drills and practise to get use to this it will still work just as it would if you do your S drills with the cylinders worn on both sides.

Fourth: Prop Wash and streamlining. When you are configured in this way streamlining is like a flat nosed 18 wheeler going down the highway in a head on wind gust. effectively about it is about the same comparison. If your cylinders are trimmed correctly then you will be equally streamlined and perhaps more so having the cylinders on both sides. The cylinders should be rigged so that they are tucked under the arm pits with the valves by the collar bone. the length of the cylinder should come directly along the body's axis, your torso, hip and thighs. If you have the correct length of cord/strap on the bottom hook the cylinder when near empty should not raise up thus increasing your drag. Mounting the cylinders one on each side puts the diver in a more evenly balanced profile. Bacause the cylinders are tucked up under your armpits and along your body's axis you've minized any increase in lateral drag (shoulder to shoulder) Your vertical drag (chest to back) does not change as you still have the doubles on your back as always.

Fifth: With cylinders mounted on each side the diver can yes still access their equipment as long as the have rigged it( consistently) to allow this. My cylinders are mounted on each side. I have no problem deploying my long hose, reaching my lights and canister, cutting tools, spare mask, reels fins etc. My arms are as they have always been with my hands held together or moving around my light looking at things. I perform valve drills and s-drills as if the stage/deco cylinders were not there.

Now while this may work for me having cylinders on both sides it may not be right for another diver. Find what works for you, work it and make it as safe as possible for YOU. Gear configuration is and will always be a constant evolving process. As new equipment designs come out, as we work towards the goals of our personal diving preferrences, the gear configuration will evolve. Hey Good Luck

 

[texdiveguy]

Another trick I use on IDing my correct gas switch bottle from the obvious listed above in this thread is to use a piece of waterproof medical tape attached to the backside in the second stage gas vent,,,you write your MOD here....now you have another checks-n-balance in your hands to look at----works very well in low/no vis situations!

 

[karstdvr]

Second:The Long Hose deployment problem concern. Yes there could be a problem if you wrap the long hose around the canister and the cylinder is mounted on the right D ring. Try moving the long hose off the cannister, mount the cylinder on a right shoulder and hip D rings and then mount the other cylinder on the left D rings. Now wrap you long hose behind your right shoulder blade under the armpit and on top off and over the clips of the cylinders, under the left armpit and behind the left shoulder, behind the neck and around to your mouth, now breathe. Deploying it is not all that difficult as it is on top of everything. Grab the second stage drop your head and slide the long hose forward, When the other diver who needs it gets it, slide your hand down the entire length of hose to make sure it deploys to full length. Nothing different here then what you should be doing if it was around your cannister. Oh and before your dive buddy needing air takes full control of the long hose check your left post to make sure your valve is open to be certain that you have air from your short hose reg.

You bring up some good points. To commit blasphemy and cause the Hog/DIR folks to choke,why not stuff the long hose? If you are breathing the long hose which can be done when the long hose is stuffed,then the only real argument is that I can't put it back on my own when it is deployed,which who cares because if it is deployed in an emergency then it isn't going back. This configuration was used safely for years before Hog,the only thing is that you'll get funny looks by others.