Understanding The USE OF DOUBLES??????

[Subcooled]

Using two tanks is actually pretty cost/time efficient:
1) gather your diving gear and get cylinders filled - one hour
2) drive to the dive site - one hour
3) chat at the shore - half an hour
4) dekit after the dive and stow gear in car - half an hour
5) drive home - one hour
6) equipment maintenance, drying and so on - one hour
and you have used five hours (incl. two hours of driving) to do one dive.

Now would you prefer a 45 min dive (15% in water) or a 90 minute dive (30% in water)?
It is pretty expensive to dive using a single cylinder only.

Doubles have several benefits (weight, redundancy, gas amount, ...see posts above) that make them often a better choice than two independent single tanks.

 

[Storker]

would you prefer a 45 min dive (15% in water) or a 90 minute dive (30% in water)?
It is pretty expensive to dive using a single cylinder only.

So bring two singles. A decent sized (80-100 cu.ft. of gas) single will last you (or me, at least) close to the NDL, at least on a proper multilevel dive. Ergo, taking two hours' worth of gas underwater isn't a significant point (for me). It's really no big hassle to bring two singles and swap them during the SI.

Renundancy is a good argument for doubles. Balance and ergonomics is a good argument for doubles. Bringing enough gas for a deco dive is a good argument for doubles. Not wanting to swap tanks during the SI is a good argument for doubles. Generally not being able to dive longer isn't a good argument for doubles.

As I've said a few times, I have quite a few clubmates who prefer doubles. For various reasons. I prefer singles. For various reasons. As long as you're not going tec, it's a question of preferences and priorities.


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[KenGordon]

I like twinsets as they reduce your dependency on a buddy enormously. Now you are not nearly as concerned about strange configs, how they will donate air or where to grab it from etc. These things are not irrelevant but become only the secondary response in case of a problem

 

[CamG]

The reason I wanted to go to doubles was to have more gas with redundancy.
My dive goals were needing more gas, for longer, deeper, colder dives.
When I started needing more time at depth I moved into doubles.

I took my time transitioning into doubles training with them on many dives before taking any tech training.
This was my path and grew into using them with my wet suit and dry suit.
I then gathered my gear and started my tech training.

CamG