You just want to see the DIR bubbas roll in hot on me, don'tcha? Let's just say it involves deep air and a couple of stops and leave it at that, ok?
Rick
Independent Doubles
- Thread starter Divesherpa
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Rick
OP
See Rick, We aren't that different after all!!
Josh Levinson
Registered
Hey guys,
So as I see from your comments, there are 2 disadvantages of using independent doubles:
1) More regulator switching. I agree that you should be comfortable with gas switching, but I also agree that you should do it as little as possible.
2) Gas from both tanks in the event of a reg failure. With a manifold, you can still have access to all your remaining gas even if one of your regs craps out. But... couldn't you do that using independants as well by putting a reg from another tank on it? For example, you could breathe off of your buddy's alternate, and switch your working reg to the tank which had the messed up reg. I know this is not ideal, but it is possible in an emergency (which is the only time you'd need to do it), and also I'm mostly just making this comment because I want to get your guys' feedback on it... I don't think I would ever rely on that technique unless I had to. Also, someone made the comment that an advantage of independants is that you can avoid losing air from both tanks. You can do that with an isolation manifold... you might lose a bit of air from both tanks until you close the isolation valve, but if you're good you can minimize the amount lost.
Incidently, I don't dive independants, nor would I unless I was sidemounting. Just trying to cause more mayhem in here
Josh
So as I see from your comments, there are 2 disadvantages of using independent doubles:
1) More regulator switching. I agree that you should be comfortable with gas switching, but I also agree that you should do it as little as possible.
2) Gas from both tanks in the event of a reg failure. With a manifold, you can still have access to all your remaining gas even if one of your regs craps out. But... couldn't you do that using independants as well by putting a reg from another tank on it? For example, you could breathe off of your buddy's alternate, and switch your working reg to the tank which had the messed up reg. I know this is not ideal, but it is possible in an emergency (which is the only time you'd need to do it), and also I'm mostly just making this comment because I want to get your guys' feedback on it... I don't think I would ever rely on that technique unless I had to. Also, someone made the comment that an advantage of independants is that you can avoid losing air from both tanks. You can do that with an isolation manifold... you might lose a bit of air from both tanks until you close the isolation valve, but if you're good you can minimize the amount lost.
Incidently, I don't dive independants, nor would I unless I was sidemounting. Just trying to cause more mayhem in here
Josh
OP
The free-flow issue is a moot(sp) point because you can simply switch to another second stage without losing hardly any gas at all. Most of my dives are stage dives, which gives me access to several 2nd stages. Changing a 2nd underwater isn't very difficult, even in no vis situations.
Long hose comes into play when diving with others. I switch very often, and always maintain more air on the long hose than the short, but independents are mainly for soloing anyway. You don't need a long hose for yourself. It does take practice to make donating second nature, but what else are you gonna do on long hangs?
As for keeping up with which reg and what guage, color coded zip ties work for me.
Independents are more work and less practical for some people, but under certain conditions I believe they actually increase safety. If not, I wouldn't dive independents at all.
Long hose comes into play when diving with others. I switch very often, and always maintain more air on the long hose than the short, but independents are mainly for soloing anyway. You don't need a long hose for yourself. It does take practice to make donating second nature, but what else are you gonna do on long hangs?
As for keeping up with which reg and what guage, color coded zip ties work for me.
Independents are more work and less practical for some people, but under certain conditions I believe they actually increase safety. If not, I wouldn't dive independents at all.
How's that again? If you shut off the free flowing regulator's tank you stop the leak, but you can't use the gas.... if you continue to breathe the free flowing reg or another second on the same reg you still have the free flow dumping your gas at a rapid rate. How is this a "moot point?" If you intend to shut off the gas and move another reg to the tank underwater.... well, you can do that I suppose in a dire emergency, but we're getting mighty complicated just to say "independent doubles are ok" don't you think?
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I think I need to clarify a point on my earlier post on my own use of independent doubles - I only use 'em in situations where (1) the dive objective requires more than one tank of gas, (2) manifolded doubles aren't available and (3) I am never in a situation where I cannot afford to abort the dive and complete any deco obligation without the entire gas supply of one cylinder and (4) it's always open water. I don't do sidemount, and probably never will. Although probably doesn't mean never.
Rick
OP
2nd stages are very easy to change. You don't lose a tanks worth of gas.
Not being able to complete the dive (for the allotted amount of back gas) with one bottle's gas supply would be a violation of 1/3's, don't ya think?
Not being able to complete the dive (for the allotted amount of back gas) with one bottle's gas supply would be a violation of 1/3's, don't ya think?
(1) Changing second stages - the most common cause of freeflow is a failed/leaking high pressure seat in the first stage. Changing second stages won't fix it.
(2) Violating thirds rule - Nope.
Rick
OP
How do you figure that being unable to complete the dive on one bottles gas supply is a violation of 1/3's? I don't understand what you mean.
What i said is that it isn't a violation of the thirds rule, not that it is. My abort criteria include the loss of a bottle.. dive over - turn the dive and head up. This could be on the descent with practically no gas used at all. Has nothing to do with the thirds rule, but rather with abort criterea. Also, I said my dives are planned so that a safe abort can be made at any time without the use of one bottle, that is, in the event of a bottle failure at any point in the dive I can safely abort, including any deco obligations.
Hope that clears it up...
Rick
OP
Understood and I agree with you totally. cheers
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