Help selecting appropriate doubles set up!!

[babybubbles]

Hi scuba board!

I'd like to hear your opinions, experiences, and tips of advice. I recently decided that I will be acquiring a set of doubles from a friend. My choices are all steel and 72, 80, or 95 cubic feet. I'm curious as to what may be the best size for me and how it might effect my trim.

I currently dive single aluminum 63's and have more air than most people on 80's.

Thanks!

 

[Scared Silly]

Welcome to the board.

The answer is - it depends.

It depends on your breathing
It depends on your body type
It depends on your exposure protection
It depends on your dive plan
It depends on your equipment configuration.

My suggestion is to go try all three sets and see what happens.

That said a common issue with double HP80s is that they are too short and divers are often head heavy. You might find LP95 to be too much for open water. As such, my guess you might find the LP72 to be just right.

 

[TSandM]

So, if you dive tiny tanks and have all the air you need, why are you going to doubles?

Assuming you are diving the typical exposure protection of Hawaii (a relatively thin wetsuit) I would not use steel doubles. Double Al80s are great to dive in warm salt water, they are universally available and relatively cheap.

 

[decompression]

I agree with TSandM, a lot goes into choosing tanks. Are you looking to extend your bottom time? Deeper dives? Multiple dives without changing tanks? What are your future dive profiles? They are a big factor in determining tank size. Share the info and I'm sure everyone will share the opinions, cheers.

 

[ajduplessis]

You are trying to get a solution to a problem that does not exsist. Why move to doubles????????

 

[waterpirate]

Tank selection is a direct result of gas planning/gas management. Sac rate, duration of planned bottom time, deco, no deco, all play a roll in tank size selection. A reason to move to doubles would also be redundancy offered by the iso manifold. A geezer that sometimes dives with us dives manifolded 63's on ndl profiles.
Eric

 

[babybubbles]

I'm not moving to doubles for more air, it's to move into technical diving. Deeper dives with deco stops. Eventually beyond the air in an al63 and for safer redundancy. Despite the average exposure protection being minimal here I wear a 7/6mil wetsuit due to doing multiple dives. I'm not sure what my sac is exactly but I can get two 40 minute dives to 40 feet or so off of one al80 and still come up from the second dive with 1000psi.
I'm not trying to solve a problem. It's about doing longer dives and venturing outside of recreational limits.

 

[eelnoraa]

Double AL80 if you wear wet suit.

Off topic, but if you need 7/6 wetsuit, maybe it is time to consider a drysuit first before double and tech diving. You can be significantly over weighted at the beginning of the dive at depth without redundant buoyancy.

 

[antattack]

One more factor, and I'm kind of surprised it wasn't the first consideration mentioned.

Your doubles kit should be designed to allow you to do the type of dive you aspire to do, and most likely to do it with a buddy who will safely complete the same dive.

The suggestion made by eelnora is a good one, if your goal is simply to get tech certified in warm water for general deep dives. If, however, you are going tech with ambitions to crawl into a cave, then the AL80s would not suit.

If you go in for the team diving idea, you will want your tanks to closely match your buddies kit. If you aren't a DIR diver and you are good on your air, but your buddy is better, you might want a larger doubles set if such a set fits your diving capabilities.

Long way to say, the folks above gave good factors to consider but there might be even more!

Dive safe!

 

[TSandM]

If, however, you are going tech with ambitions to crawl into a cave, then the AL80s would not suit.

Al80's are almost ubiquitous in cave diving in Mexico.

Given the additional information from the OP, I stick with my original recommendations. Al80s are great tanks for warm water diving, and they're widely available and inexpensive. They are also not horrendously negative when full, which is important if the OP is going to continue diving wet. The one downside of Al80s is that they get rather obnoxiously butt-light when empty, but if the OP is using that much neoprene, he'll have room to put some weight on the bottom of the rig to help counteract that. I dive Al80s in my dry suit with 7 lbs hanging off the bottom bolt, and that balances me pretty nicely.

They aren't a huge gas supply, but they'll make the rock bottom for Tech 1 level dives, and if the OP decides to go on to bigger dives than that, that will be plenty of time to consider investing in a dry suit and a set of steels.