My journey into tech

[Lorenzoid]

Accidentally diving with a closed isolator valve: diver runs suddenly OOA. Sure it's recoverable by switching the reg, but that's not what comes to your mind as a solution right away if you have no experience with doubles.

The "surprise closed isolator" happened at least once while my wife and I were learning doubles. This happened in the shallows of a lake, though. Knowing that just such a thing could happen, we practiced with the doubles in benign environments for a good long time until we knew how to handle them. Oh, and then we dived from a boat off the coast of North Carolina, and my wife experienced what we figured out afterwards was a right post roll-off when the valve handwheel caught the line between the hang bar and the pitching boat. Another learning experience. Yes, there are things that can happen.

 

[abnfrog]

first of all im not getting into a pissing match with you guruboy ......if you dive doubles WITHOUT using the isolator drills then its just 2 tanks not 1 ,(really just weight ) second when you get that instructor card maybe you might get to know what your talking about , as a DM with what 4-5 years diving you are pretty arrogant you know it all , (I feel sorry for the instructor you work with ) I think your arrogance is going to follow you into teaching , as of your option of me I could care less , and by the way im an IT/IE instructor , I really don't think you attain the highest rating in the agency by being a moron, you on the other hand ......................not responding to you again as you don't understand

 

[guruboy]

first of all im getting into a pissing match with you guruboy ......if you dive doubles WITHOUT using the isolator drills then its just 2 tanks not 1 ,(really just weight ) second when you get that instructor card maybe you might get to know what your talking about , as a DM with what 4-5 years diving you are pretty arrogant you know it all , (I feel sorry for the instructor you work with ) I think your arrogance is going to follow you into teaching , as of your option of me I could care less , and by the way im an IT/IE instructor , I really don't think you attain the highest rating in the agency by being a moron, you on the other hand ......................not responding to you again as you don't understand

you do you, man. congrats on your ratings.

BTW, for the sake of anyone else reading this that doesn't know how to dive doubles, it's only two tanks if the isolator is CLOSED.

 

[ChuckP]

So the suggestion for someone that wants to dive doubles is what as it relates to "instruction" before an actual dive?

Get some equipment suggestions from experienced folks? - I'd say that happened
Educate yourself about your equipment? - yep
Spend some time in a pool checking trim and getting used to equipment? - done that.....
Do a couple dives to see how things go - done that too

What more should one do? At some point you have to dive...

Dear lord, diving doubles is not that much different than any open water single tank dive for someone with 100+ dives and those dives aren't cushy 20 dives per year fall off the boat valet service follow the dive master dives. This person has had 100+ dives lugging and setting up her own gear, diving her own plans, in a dry suit, carrying a spare bottle I think in 40 degree water worrying about regs freezing....... She ought to have strapped a set of doubles on and fell off a boat on any wreck within rec limits in the great lakes skipping the dang pool but that ain't her personality or what she wanted to do - which is AOK cause everyone ain't the same.

 

[PfcAJ]

first of all im getting into a pissing match with you guruboy ......if you dive doubles WITHOUT using the isolator drills then its just 2 tanks not 1 ,(really just weight ) second when you get that instructor card maybe you might get to know what your talking about , as a DM with what 4-5 years diving you are pretty arrogant you know it all , (I feel sorry for the instructor you work with ) I think your arrogance is going to follow you into teaching , as of your option of me I could care less , and by the way im an IT/IE instructor , I really don't think you attain the highest rating in the agency by being a moron, you on the other hand ......................not responding to you again as you don't understand

It’s almost a prerequisite.

 

[barth]

Accidentally diving with a closed isolator valve: diver runs suddenly OOA. Sure it's recoverable by switching the reg, but that's not what comes to your mind as a solution right away if you have no experience with doubles.

We did a week of trimix diving. After the last day they did remove all the gas of the doubles because the price of the helium.

A buddy wants his set filled with nitrox. At home he noticed his isolator was closed. One tank was filled with oxygen and one tank was filled with nitrox.

You should always be careful when a isolator is closed. Just switching regulators when a isolator is closed can kill you. Or just open an isolator and just go diving can also kill you.

 

[Rechno]

From what I read here, I think I missed something important in my diving progression…. Doubles seem to be rocket science.
YES, there are more failure points then diving with single tanks…. more o-rings and possibly an isolator manifold. But if you payed attention in pre dive checks and have some grey cells, you should be able to adapt to this new "challenge". Hey, on my isolator it even reads open / close with some nice arrows, so without any help from outside I was able to figure out in what direction to twist.

I dont see why one should not just try them out and gain experience in shallow easy conditions. Nobody seems to recommend to start with a deco-dive as a check-out dive as soon as you buy your first doubles.

 

[guruboy]

We did a week of trimix diving. After the last day they did remove all the gas of the doubles because the price of the helium.

A buddy wants his set filled with nitrox. At home he noticed his isolator was closed. One tank was filled with oxygen and one tank was filled with nitrox.

You should always be careful when a isolator is closed. Just switching regulators when a isolator is closed can kill you. Or just open an isolator and just go diving can also kill you.

Did you intend to type ”did NOT remove” instead?

Or did you maybe extract with a booster?

 

[Gareth J]

Hmm

I've been diving twins (doubles) since 95. Having read this thread I should some of the views I should have died years ago.
I progressed from single, single + pony, twins (doubles) - Independent, twins (doubles) - manifold.

There is far more information readily available now, than when I started. Far more people using twins able to give advice. A course has the advantage of all the information in one place, and concentrating on the skills for the period of the course, getting a foundation. The actual work is done after the course with practice, experimentation, and adjustment.

I know a lot of people who dive twins with the isolator OFF. Diving them as independent twins. They have redundancy, if required, can open the isolator if needed. I have no real issue with this, having dived independents for years before I switched to a manifolded set. In fact, diving independent twins generally means the diver is more disciplined with gas management.
I know a lot who use inverted twins. Having dived a rebreather for years now, if I went back to twins I think I would invert them now.

I've had "rolloff's", on single cylinder setups. The only unique issue I've suffered on twins is a blocked isolator, on a set of rented cylinders.
I have seen the isolator sheared off, after being hit by the boat in a rough sea.


On the filling side, I've seen far more sets of manifolded twins on boats with only one side filled than independent twins. Poor procedure by the 'gas monkey' poor procedure by the diver. That said, I've seen second cylinders on boats that have arrived empty.

 

[KenGordon]

I was at a (shallow) inland site recently where the gas monkey refused to touch the isolator. That seems more likely to result in an issue than always insisting on opening it.