What size of steel tank for beginner doubles?

[CamG]

Just wondering if any size is easier to begin with? I have started researching and trying to learn all I can. Any information is welcome. I am wrestling with the used or new question also. What I do know is more bottom time is awesome! I am not against either new or used, just would like to purchase the right tanks! Thanks for any help. Keep diving....keep training....keep learning!

 

[PerroneFord]

How tall are you?

 

[Anthony Turner]

I have been using steel twins 72's for the last 12 months an have become pretty comphy with them. Looking at going to al80's because of weighting issues. I have heard that if a person is using a wetsuit that al's is the best way to go ????

 

[WD8CDH]

Well...........The smaller and lighter the tanks, the easier to carry.

It really depends on your type of diving. In general, I prefer 3442psi steel over the LP steel tanks. Unfortunatly my favorite size steel tank for doubles is not available in the US. My Steel favorite is the "7 liter" size. They are only 5.5" in diameter and make great compact doubles. In the US, the only pressure rating makes them 45 CF. In Europe, you can get that tank size in 300 bar where they would hold about 75 CF.

3442psi 80's are still managable as doubles and have good buoyancy characteristics so that would be my choice if I ever stoped diving with my skinny triples.

 

[TSandM]

Cam, the answer is going to depend somewhat on your body habitus. But before getting into that, I'd like to ask for some more information about why you are considering transitioning into doubles. Your original post makes it sound as though what you're in search of is more bottom time, and if that's the case, there are some other ways to achieve it.

The first one is to lower your gas consumption, which can be done by increasing the efficiency of your diving. Search for a thread entitled "Gas Guzzler", and you'll see a lot of tips for doing this.

Second, you can get as much gas as double 72s out of a single HP 130. And you're not dealing with the complexities of a manifold, or the weight and bulk of double tanks.

I dive doubles for two reasons: The big one is that I cave dive, and caves require doubles (or the equivalent redundancy), and I need to stay in practice to haul the weight and do the valve shutdown drills I need to be good at. The other one is for the occasional deep dives I do, where I value the redundancy that doubles afford.

If you aren't doing a lot of deep diving (and by this, I'll define diving between 100 and 130 feet), and you aren't planning on going into decompression or overhead diving, I think you'd be happier with a couple big steel tanks instead. But if you ARE heading one of those directions, give us some info on your height and weight and current gear configuration, and we'll all pitch in with our personal tank recommendations

 

[dsteding]

Lynne makes some excellent points here, I'd listen to them. I dive doubles for dives in the 90-110 foot range, or where I may be exploring something/somewhere that I just don't have a complete picture of yet, and may want the gas.

I'll also use doubles for technical diving when I get into that. Of my last 150 dives, probably 100 of them were in doubles, but I'm now diving a single tank more and more again. The point Lynne makes about a large steel single is a good one.

But, if you are heading the technical/cave route, then start by figuring out what works for your body size. Doubles can be hell on the back, and getting the right size tank can take some trial and error.

 

[crpntr133]

What can you lift is the big one. From there read above.

I have a set of Worthington LP 77's that I dearly love. But I am thinking of doubling my 85's. I'm pretty sure that I won't be going to 100 since they are hard to lift for me.

 

[Jay Roy]

My vote for a first set of dub's is alum 80's....Fairly cheap to put together...nice and light and therefore easier on the back...and they can be split up and used for stages further down the road..
My first set was a pair of PST LP80's....Also a nice set of doubles...But I'd still go with the aluminum 80's..I've been diving my 130's all the time for the last few years..and I just put a set of alum 80's together a few months ago..I love em..I wish I would have gotten a set years ago...

 

[DA Aquamaster]

My vote for a first set of dub's is alum 80's....Fairly cheap to put together...nice and light and therefore easier on the back...and they can be split up and used for stages further down the road..
My first set was a pair of PST LP80's....Also a nice set of doubles...But I'd still go with the aluminum 80's..I've been diving my 130's all the time for the last few years..and I just put a set of alum 80's together a few months ago..I love em..I wish I would have gotten a set years ago...

Double 80's are fine for wet suit diving as they are not excessively negative and are very stable.

But on the other hand, they are comparatively long for a short diver and are no lighter than a pair of E7-100's or X7-100's. So for the same weight, same diameter and about 4 inches less lennght, you could have double 100's. And if you dive a fairly thick exposure suit or drysuit and need some lead to acheive neutral bouyancy at the end of the dive, you will actually save total equipment weight with the double 100's as you can drop about 7-8 lbs of weight compared to double 80's.

That said, a set of full double 80's or 100's, with SS back plate, wing, can light, lift bags, etc, will still be in the 120 lb range.

I like 3442 psi PST E or Worthington X series tanks myself.

LP tanks are practically speaking the same tanks weight and size wise as 3442 psi tanks but with a lot less capacity due to the lower service pressure. That means a lot more weight for a given volume of gas (but no problems getting a solid fill). And some places will give you a 3400 psi fill in your 2400 psi tank anyway - it just happens to be illegal.

So you can approach it two ways:

1. Buy 3442 psi tanks for the gas volume you want in order to minimize weight (or alternatively select them based on the maximum weight you can carry, or the maximum lenght you are comfortable with) or,

2. If weight and lenght are not big issues, buy larger capacity 3442 psi tanks that will give you the same gas capacity at 2640 psi as the LP tank you would otherwise choose - giving you the benefits of an overfill, but legally, in the same size and weight package as the LP tank you would have purchased.

Either way there is little or no reason to buy an LP tank when you compare dimensions, bouyancy traits and capacities at various pressures as the 3442 psi tanks offer more gas in the same size/weight package.

 

[jacksatlanta]

Another factor worth considering that has not yet been mentioned is the set of doubles center of gravity on your back and its effect on trim. Each tank particularly steel ones will have its center of gravity in a slightly different spot on your back and therefore affect your trim in the water differently. The best tanks for doubles for me were LP Faber 95's overfilled, where HP119's arguably a similar tank makes me too leg heavy. Same thing in smaller tanks the LP77 is very nice but my Faber LP 85's put me a little too head down. Before buying get to a technical store if possible and try any set you are considering before buying, doubles are a big step and something you don't want to have to "live with".