Sidemount with 50% and 100% mix

[superspeed]

Just out of interest, what sort of dives were you doing that require the 80cf 100% mix for 2 dives? I could probably do around a total of 36min of deco on a 40cf at 6m using a 20% reserve. I think the question is, how long would it take me to build enough experience to execute dives that's going to exceed that. I don't see it happening anytime soon for now... but then again...

Superspeed, what are your second stage hose lengths for the 2 stage / deco bottles?

Its more the 2nd dive that gets me. If you have a 40cuft tank and use lets say 20cuft for the first dive...using 1/3 rule for reserve you only have room to do about 13cuft of deco on dive two. Nothing wrong with that but if you for any reason end up extending your first dive or using a little more o2 than you planned you could run into a planning problem and for me its just not worth not taking the 80, in the water its not really much of a problem.

36" for both deco bottles, when im using them i run behind neck and over right shoulder.

 

[DevonDiver]

Left side 50% bottle (80cf AL clipped off below primary): regulator hose around back of neck

I never run deco hoses around the neck. I think it's just one step nearer to an avoidable human error. Hoses are 30" and route directly from the cylinder to mouth. I also use ANDI contents tags on the hose (below the reg) as a fail-safe, in addition to cylinder MOD decals and full gas switch protocols.

I don't see any need to 'neck route' a deco cylinder. You don't want the hose there, for any reason, before you reach stop depth. Once at stop depth, the need for simplicity and error reduction outweighs any concept of streamlining.

Wanted to add a 100% mix into the setup, most likely I would get another 80cf AL, anyone would suggest the 40cf AL may be a better option for 100%?

Cylinder volume is dictated by gas requirement.

I have been told by someone to keep all deco bottles on the left? Is this practice mainly for BM people?

This primarily arose from the demands of scootering (in caves). If you're not a DIR/GUE/UTD adept, with an intention to scooter, then it's probably not a big consideration. Bear in mind that GUE doesn't encompass sidemount diving... so that pretty much leaves you with a small number of UTD divers who sidemount. It'd be worth directing that question at them specifically to get their opinion (via the DIR forum).

On balance, far more divers probably rig their cylinders on either side. In doing so, they'd probably follow the 'right-rich/left-lean' philosophy. That's what I do.

If the right side is the correct spot for the 100% mix, what will be the hose routing? I want to avoid using left handed regs / 90 degree swivles etc. Should it go across the chest again like the current primary right bottle?

Yep, right-rich/left-lean. Hoses are stowed on the cylinders during the dive... un-stowed when you need them, breathed, then returned to tank bungees when you move on/up to the next gas. This'll be the same as you were (should have been?) taught on whatever version of advanced nitrox/decompression procedures training you undertook.

Using sidemount configuration doesn't (shouldn't) entail any deviation from full and proper gas switching protocols... or basic considerations for preventing/lessening the risk of killing yourself by accessing the wrong regulator at the wrong depth. IMHO, the necessity to gas switch during the dive on sidemount brings about a much higher necessity to analyse your kit and ensure that you can never accidentally stick the wrong regulator in your mouth under stress..

Doing a proper 'Tec Sidemount' or re-taking/refreshing tech training in sidemount, would be the best solution to the questions you are posing. The issues you are raising are ones that will kill you quite easily... that's not really a sound argument for getting online advice from strangers and 'learning from mistakes' by doing the dives without specific and supervised rehearsal.

 

[ianr33]

Hoses are stowed on the cylinders during the dive... un-stowed when you need them, breathed, then returned to tank bungees when you move on/up to the next gas. This'll be the same as you were (should have been?) taught on whatever version of advanced nitrox/decompression procedures training you undertook.

A small point bit I find it helpful: When I've almost finished my 30 foot stop I'll switch back to the left tank,bungeed sidemount (backgas) reg and stow the 50% reg. Move up to 20 feet and then switch to 100%. Going to backgas for a couple of minutes makes no real difference from a deco perspective and saves having hoses all over the place

Using sidemount configuration doesn't (shouldn't) entail any deviation from full and proper gas switching protocols... or basic considerations for preventing/lessening the risk of killing yourself by accessing the wrong regulator at the wrong depth. IMHO, the necessity to gas switch during the dive on sidemount brings about a much higher necessity to analyse your kit and ensure that you can never accidentally stick the wrong regulator in your mouth under stress..

Agreed.Which is a real good reason to make totally sure all deco tanks have the valve OFF during a dive. Even if you did somehow manage to get the wrong reg you'll only get one breath from it.

 

[beanojones]

I never run deco hoses around the neck. I think it's just one step nearer to an avoidable human error. Hoses are 30" and route directly from the cylinder to mouth. I also use ANDI contents tags on the hose (below the reg) as a fail-safe, in addition to cylinder MOD decals and full gas switch protocols.

I don't see any need to 'neck route' a deco cylinder. You don't want the hose there, for any reason, before you reach stop depth. Once at stop depth, the need for simplicity and error reduction outweighs any concept of streamlining.

Two reasons to use a neck loop:

1. There is nothing less comfortable than having to bite a reg to keep it in the mouth, especially for deco. Without the neck loop most regs are pulled by the hose. Of course I also use a 45 or 120 degree swivel on the looped regs, so I can go underarm with them as well, and with the 120 I can go underarm from either side.

2. The tank trails better than it rides in front so on decos with a long swim, it is useful to nose clip the tank to the buttplate, and let it trail. That makes a 40" hose pretty much necessary.

(Also the usual gas sharing sucks with hoses shorter than octo length. But then again gas sharing sucks for hoses without swivels too.)

IMHO, the necessity to gas switch during the dive on sidemount brings about a much higher necessity to analyse your kit and ensure that you can never accidentally stick the wrong regulator in your mouth under stress..

This point makes me wonder more about using NetDoc's double choker system. I like it to begin with, and this point make me like it more.

 

[The Chairman]

This point makes me wonder more about using NetDoc's double choker system. I like it to begin with, and this point make me like it more.

Thanks for the kind words! Yeah, I don't want anything around my neck. Why? It becomes harder to trace the hose back to it's source. I want to SEE the hose route back to the tank it originates from. Also, I hate the feel of hoses around my neck.

Why no 2nd stage elbows??? They are really what makes sidemounting easy and streamlined. I'm not talking about swivels, though I have used those as well, I'm talking about elbows like this from www.DiveGearExpress.com. At only $7.50 a piece, they are more than awesome.

 

[mulla]

Thanks everyone for your input, appreciate every comment. Going to try various configs in rec dive levels in the comming months and see which method I prefer. When I was taught deco hose is always round back of neck, I might try the reg straight up method, sounds like a good idea for deco gas.

 

[CamG]

Mulla when I was trained in Deco procedures we pulled our deco gas reg. verified the gas with our buddy, ran the hose around our neck then switched to Deco gas.
Since, I have ran it straight up and also around.
BUT THE HOSE IS ALWAYS STOWED BUNGEED TO THE BOTTLE WHILE NOT IT USE.
Either configuration will work but the stowed until ready to use will force you track the gas to the tank to fetch your deco reg.
MAKE NO MISTAKE VERIFY YOUR GAS CAREFULLY!

The saddest accident report I have read is a bad gas switch!
Totally preventable just a small mistake that at depth is 100% fatal!
NO SECOND CHANCES, GAME OVER!

CamG Keep Diving....Keep Training....Keep Learning!

ps. Not trying to be captain doom but this was a major in our training that our Instructor made very clear!

 

[Tortuga68]

... a small mistake that at depth is 100% fatal!
NO SECOND CHANCES, GAME OVER!

Certainly something to be avoided but hardly instant death... There are many cases of divers surviving such incidents either permanently or temporarily

 

[PfcAJ]

and probably a lot more where they died.

breathing the wrong gas is one of the most dangerous things in technical diving.

 

[DA Aquamaster]

Certainly something to be avoided but hardly instant death... There are many cases of divers surviving such incidents either permanently or temporarily

AJ is correct, switching to the wrong gas has consistently been the number one killer of technical divers.