Doubles?

[DA Aquamaster]

I started with independent douubles. Thes pros are more flexibility - you can dive one then the other more or less like a giant pony bottle on recreatioanl dives. Alternatively, you can switch regs (use 1/3rd of the first tank, then switch and use 2/3rds of the second tank, then switch back and use the 2nd third of the first tank - turning the dive after you breathe 1/3rd of the secodn tank. That keeps your reserve gas properly split and ensures you have enough gas in either tank to exit in the event you lose the entire contents of the other tank.

They were taboo for awhile, then people realized side mount which is the same thing. The downside of independnent doubles is that a set of travel bands costs as much as a manifold so the cost is a wash.

If you are only doing recreational diving there is no need to know how to do valve drills etc and the added complexity is not going to kill you. You also do not need formal training just to use doubles. In fact single outlet doubles used to be common among OW divers. A mentor is a great help in terms of getting your configuration right, avoiding any bad habits and learning any technical doubles skills prior to showing up for a class where doubles may be used.

A bigger mistake I see is a diver who delays using doubles until he or she starts technical dive training. It takes time to get used to them and between resolving configuration issues and dealing with the increased task loading that can result when things are not exactly right, a new doubles diver is too busy and to overloaded to actually learn anything in a tech class. So I am firm believer that if a diver is trechnically inclined that he or she shoudl start using them soon while still in the developmental OW phase.

And for what it is worth I have seen divers with 10-20 dives that can dive rings around divers with a couple hundred dives, so the number of dives a person has means very little - other than on an internet board.

 

[PerroneFord]

the only problem with getting a hp130 is they are huge and its a waste if you are going to doubles later on.

Why? Just get a second one, and you're golden. Several of my friends dive double 130s. I'd prefer double 85s and a stage, but that's just me.

 

[atedeschi]

because they are monsters, LOL

Who really needs that much gas. What types of dives are you using that much gas?

 

[SparticleBrane]

I use double 130s for cave diving...


To the OP -- I am with everyone else. Go get some more diving experience. At this point you don't know what you don't know. We are all happy that you are enthusiastic, but experience is what you want at this point.

 

[Blackwood]

the only problem with getting a hp130 is they are... a waste if you are going to doubles later on.

Double 130s are great, especially for gas reserves. Plus you can get about 200CF of gas out of them even if there aren't any HP fills available.

I wouldn't mind having a couple of sets for deep boat dives (though I think I'd prefer LP120s)

 

[PerroneFord]

Who really needs that much gas. What types of dives are you using that much gas?

I've used that much gas and more on dives. I know many people who use 5-10x that much gas on their dives. It all depends on what you are doing.

Twin 130s don't last all that long at 200+ ft. Especially, if you are following proper gas reserve rules.

 

[ivobj]

Worst case, IMO, is a manifold failure.

You are right, my mistake, didn`t expressed myself right, both you and JDMerk are right, manifold failure is the worst case and in this case you can loose all your air and will probably have to share with your buddy (if the problem is a severe leak, a minor leak would probably reduce the air available, but may still give you enough to safely ascent, specially in shallow waters)

I still defend manifolded doubles though, as the stats are largely tending to regulator failure, which intuitively is easy to understand and makes perfect sense, as with more moveable parts, and in contact with the water, you have much more chances of a failure. I understand that if you take apropriate care and perform a routine check and predive test of your manifold and bottle valves, and never lift the doubles by the manifold, there is a very small chance of failure in these parts.

As reg failure is the situation in which manifolded doubles are better, keeping all your air available, in opposition to loosing half your air supply with isolated doubles, in my opinion, statistically you have much more chances to be in an worse situation with isolated doubles. I admit though that this is a serious issue in deeper dives, when you must have more air to return safely, in shallow dives, as is the subject of this thread, isolated doubles or manifolded doubles may not differ much, as even with an isolated double and reg failure you will probably have plenty of air to return safely to the surface.

 

[ONESPEED]

I know the dangers of diving so don't tell me not to do It.....

 

[atedeschi]

sorry had my tanks mixed up, yeah 130s are like lp108s, its lp120 9 dont know why you would want. but for starting out you dont need tanks that big, go with double al80s, then later they can always be converted to deco bottles.

 

[rstofer]

So, 2 130's would weigh 86# plus 21# for air and maybe 10# for the manifold and regs. Total 117#. There's no way in the world I could hump that from the parking lot, across the beach and through the surf! I'll leave this for younger people. If I did a face plant on exit, I would never be able to get up!

That, and your buddy has to have a similar configuration. Good luck with that! Not everybody wants to hump that much weight.

Richard