Why recreational backmount doubles

[Subcooled]

It is twice the gas (and dive time) for the same dive trip - unless you change your cylinder half-way during the dive.
It is better balanced - sidemount is of course superior.
Safety benefits (two first stages) in overhead environments.

 

[Wibble]

You do a longer single dive, say two hours. Easy if you’ve the right kit and skills.

Example, 35m/120ft wreck. Easy enough on a single (plus pony or a solid buddy) but you’re rather restricted to a short 45 to 60 min dive. With a twinset+deco gas it’s an easy 90 to 120 min dive. On a rebreather it’s whatever you want to do.

If you’ve 4 hours of steaming to and from the site it makes no sense to do a short dive, and doubly so to do an NDL dive.

 

[AfterDark]

I never asked myself why I use doubles, always seemed obvious, more bottom time when I want it and redundancy when I'm solo diving.

 

[Wibble]

I never asked myself why I use doubles, always seemed obvious, more bottom time when I want it and redundancy when I'm solo diving.

FIFY

 

[Centrals]

Most operators in SE Asia do not have twin set unless it is tec diving friendly.
11L tank is enough for me for a single dive to 40m(non deco).
No one dies from having too much gas!!!

 

[Nemrod]

This being in the Advanced Forum and the subject pertaining to "recreational" use and not technical use, I will say certainly for me that there is little or really no reason outside of solo if even then to use twin sets. Air/gas, is not the limiting factor most of the time for me, deco is. And advanced divers and recreational divers do not routinely perform overhead/deco dives. I can easily get into deco on an aluminum 64. Redundancy, like what? I have a buddy, that is my redundancy and if I am solo I would carry a pony so that I do not need to handle that weight of a full size cylinders on my back outside of the water. And solo diving, at the advanced level certs is non-deco. I do not need full size back mounted tanks or ungainly and complicated rigging of side mounted tanks for buddy recreational or solo recreational dives.

James

 

[Centrals]

This is a FREE world.
Twin set for recreational dive? Your choice but not mine.
No right or wrong.

 

[AfterDark]

Unlike @Nemrod I have never been able to reach NDL at any depth with any of the single tanks I own. My tank slinging trial time was enough for me to discover that wasn't for me.

So, for me doubles have always been the way to go if I wanted more bottom time or redundancy. Mike Nelson's triple tanks were always a source of envy to me!

HP large capacity tanks can probably fill that need pretty well these days. Redundancy however still requires 2 tanks.

 

[happy-diver]

What's redundancy anyway, more tanks or diving within the bounds of what you have

Ungainly:
Delving underwater with your tanks affixed to you with string then pretending to dive
Yeah it's in the dikshunary

 

[Nemrod]

Unlike @Nemrod I have never been able to reach NDL at any depth with any of the single tanks I own. My tank slinging trial time was enough for me to discover that wasn't for me.

So, for me doubles have always been the way to go if I wanted more bottom time or redundancy. Mike Nelson's triple tanks were always a source of envy to me!

HP large capacity tanks can probably fill that need pretty well these days. Redundancy however still requires 2 tanks.

I remember my instructor said that it was impossible to go into deco with a steel 72 because that is why that capacity was developed. Huh! An aluminum 64 is all I need to bust deco at anything over 60 feet or so. And when I dive tables or square profiles I use the old Navy Tables because I know them even for multilevel dives by heart and can compute on the fly. But then I got me some new fangled 'puters so with some evasive (of deco) planning I could exhaust an 80 and not go into deco I suppose, if I went deep and then came up shallow and strung the dive out. I just do not need doubles for any sort of non-deco recreational dives unless we are doing the Spiegel or something like that and staying at 130 feet for the duration. And even then I do okay with an aluminum 80.

James