Short + Doubles = ?

[Unproductive]

Hey,
Im thinking about getting my first set of tanks. Im 5'5'' and I weight 165lbs. Yes I know every person is different and I will just have to try some tanks out, but I was wondering what short-er people are diving for doubles. I was looking at lp 95's and E8 119's. I was also looking at 130's and I was thinking overkill?!? My main type of diving is NC/VA wreck diving, quarries ect.... I will be using singles right now, but I hope to double em up in the future ie this summer. So what do you think, should I go with something smaller or just go all out and get some 130's?
Thanks,
Justin

 

[Doc Intrepid]

So what do you think, should I go with something smaller or just go all out and get some 130's?

Justin,

Remember that tanks are part of a system - each part interacts with the others in terms of bouyancy and especially trim. "Just going out and getting some 130s" is certainly do-able, but you might lose some serious money (and time) when you have to sell them and get something that works better. Other things to consider include whether you're diving in a wetsuit or drysuit, and what sort of diving are you contemplating: purely recreational profiles? Or dives in Morehead City that involve staged decompression?

There are some very nice E8-80 tanks out this year from PST that are shorter tanks. Same with PST's 100s. The E8-119s may work well for you also, but it depends on other factors like where your weight is distributed and how the tanks impact on your personal bouyancy - what works for others may not work for you. Here is a matrix showing the relative heights and weights of the PST tanks:
http://www.lloydbaileysscuba.com/PST E Series Tanks.htm

If cost is a factor, one of the nicest choices available for wrecks and shallow deco stuff is often a set of double steel 72s. They are lower cost to acquire, balance nicely, are comparatively lightweight, and can be pumped up to the equivalent of a set of aluminum 80s (or higher - if you own your own fill station!)

Depending on how close you are to my neck of the woods, I know a diveshop that might be able to let you try a set of the PSTs in a quarry, to see how they would interact with the rest of your rig. You could also try one of my sets of 130s to see how they feel. I also have a friend who owns five or six sets of the 72s, bet he'd let you try a set for comparison purposes.

Take it from a guy who bought a set of E8-119s and did headstands with them, eventually trading them for a set of 130s. Its worth your time and effort to find a set that trims you out properly and then buy right the first time, rather than screwing around with buying and selling first one set and then another and another. I encourage you to find someone near you and compare and contrast a few sets before you drop your own ching into doubles.

The best learning is done using OPM - 'other people's money'. Try before you buy.

Later,

Doc

 

[sailingking]

The 130's will be way to big.
I use the oms 125's which are 29" tall, which is the perfect hight for me (I'm 6'2)
My friend loves the size of the pst 130's same size as the oms 112's (he is 6 foot)

You are going to want to decide based on the type of diving you are doing and also the length of your torso. But for your height I would suggest 98's and smaller. (leaning toward smaller)

If you aren't doing technical dives, then even some faber 66's or the intermidiate pressure ones that were rated to 3300 and 72cf (distributed by scubapro). Those tanks are nice and small. Another option is to double up to old steel 72's, usualy inexpensive and they still hold ~143 cf at 2250. I usualy bring mine up to 2600 which gives you 165cf, more than you will need unless it's a really technical dive, in which case you bring a bunch of stages.

 

[DA Aquamaster]

My spouse uses Faber 72's they are only about 20 inches long, weigh 29 lbs and are well suited to her height.

Faber LP 95's are still only 24 inches long, so they would be a good choice if more capacity were needed, but at 37b lbs they are also 8 lbs heavier than the Faber 72.

LP 85's are a good compromise as they are still a reasonable AL 80 size and weight at 26 inches long but only 2 lbs heavier than the 72 at 31 lbs.

E7-100's are perhaps ideal for a 100 cu ft tank as they are 24 inches long and weigh only 33 lbs each, but you need nearly 3500 psi available to get a full fill.

Larger capacity tanks invariably end up being at least 2 to 3 inches taller which becomes problematic with a short torso and much heavier, so you'd need a strong justification for needing more gas with doubles to justify the additional size and weight.

Also, don't overlook the plain old AL 80. They are inexpensive compared to all the other new purchase options and make great doubles. And the 154 cu ft available (103 cu ft with a 1/3 left in reserve) will take you a long way in your tech career. You will be diving very deep and very long before you discover that double 80's are not enough.

AL 80's are also useful if you do get into really deep diving where you want more than an AL 40 for deco/travel gas. They make excellent deco and stage bottles, a role that steel tanks are ill suited for due to their negative bouyancy.

And when you reach that point, I'd consider E7-100's as they would offer 40 more cu ft when doubled but would do it with a couple pounds less tank weight and about 10 lbs less lead on your belt required to achieve neutral bouyancy.

Personally, I use older generic steel 72's as they are light weight (29 lbs) compact (6.75 in diameter/24 inches tall), durable and readily available at bargain prices. The local diving here is limited to 150 ft unless you bring a shovel so a pair of steel 72's when used with a deco bottle will allow 20 to 25 minutes at 150 ft with a 1/3 reserve. When I travel I'll use rental 80's in a set of travel bands with an additional 8 lbs of weight being the only substantial change needed.

Generic steel 72's offer 64.7 cu ft at 2250 psi or 71.2 psi at 2475 psi. I will admit to the occasisonal overfill to about 2600 psi and 74.8 cu ft (very close to an AL 80's 77 cu ft capacity) on longer dives where a little more gas is desireable.

 

[Unproductive]

My primary type of diving right now is in Morehead City/ VA Beach ect.... I've only done the wrecks in <70ft, but im looking this summer to get into the deepers ones, maybe some of the subs. I know these are at like 120ish and I didn't want to get a stupid pony bottle, so I was looking at some doubles that I could make two good dives on, no deco. I dive in a dry suit most of the time, but sometimes a wetsuit in NC/SC. I actually have 2 72's a buddy is willing to give to me, but I know this won't be enough gas for 2 deep dives. I was also looking at AL80's, but I think if im going to spend the money I might as well do it right the first time. Also Doc, do you know if VAScuba rents doubles? Thanks for all the help, and if anyone is my height please tell me what your using!

 

[Mark Vlahos]

My primary type of diving right now is in Morehead City/ VA Beach ect.... I've only done the wrecks in <70ft, but im looking this summer to get into the deepers ones, maybe some of the subs. I know these are at like 120ish and I didn't want to get a stupid pony bottle, so I was looking at some doubles that I could make two good dives on, no deco. I dive in a dry suit most of the time, but sometimes a wetsuit in NC/SC. I actually have 2 72's a buddy is willing to give to me, but I know this won't be enough gas for 2 deep dives. I was also looking at AL80's, but I think if im going to spend the money I might as well do it right the first time. Also Doc, do you know if VAScuba rents doubles? Thanks for all the help, and if anyone is my height please tell me what your using!

VAScuba does rent double tanks, don't forget the additional cost of renting regulators configured for double tanks though. I would talk to one of the folks there as just jumping in the water with double tanks on is a little more involved than you might think, the aircell on your wing needs to be appropriately sized and shaped, and you need to be ready for the increased bulk on your back. I am sure that if you want to go this route you would do well to talk to the folks at the shop. It is not exactly rocket science but I was much more comfortable having an instructor with me the first time I put doubles on. You need to know about valve drills and other things.

Mark Vlahos

 

[DA Aquamaster]

My primary type of diving right now is in Morehead City/ VA Beach ect.... I've only done the wrecks in <70ft, but im looking this summer to get into the deepers ones, maybe some of the subs. I know these are at like 120ish and I didn't want to get a stupid pony bottle, so I was looking at some doubles that I could make two good dives on, no deco. I dive in a dry suit most of the time, but sometimes a wetsuit in NC/SC. I actually have 2 72's a buddy is willing to give to me, but I know this won't be enough gas for 2 deep dives. I was also looking at AL80's, but I think if im going to spend the money I might as well do it right the first time.

I think you are perhaps missing the point of some of the advice that has been given. It's not a matter of getting it right to start with, it's a matter of getting tanks that are suited to your diving with a minimum number of compromises. Larger capacity tanks almost always mean more compromises.

Being 5'9", I don't like tanks larger in lenght than an AL 80, at 5'5" you need to give that dimension serious consideration, more so than capacity, given your intended dives. You could take along a 120 or 130 or maybe even double 120's or 130's but it's overkill and your diving will suffer from the compromises involved.

If you are looking at 120ft dives with no deco, a single 80 will get you in more than enough trouble so double 80's would be adequate to get you in trouble on a pair of dives. But, regardless of what you use, splitting two dives across one set of doubles is not always a good idea.

You'd need large doubles to be able to do it with an adequately large reserve on the second dive and even then you'd end up with less bottom time or less reserve than if you spent the same money and bought two sets of double 72's or double 80's rather than one set of larger double whatevers.

If you already have access to a free set of steel 72's, spend money on two more steel 72's and a pair of manifolds. You will get a lot more tank for the buck and will have way more gas than you need for two dives per day to the depths you are talking about. Unless you are a real hoover, you could expect 20 minutes at 120 ft easily with a 1/3 rd reserve with a pair of 72's and that is a deco dive even with US Navy tables.

If you can rent doubles in the area, I'd suggest renting for awhile so that you can get a better idea what you need and what you don't need.

 

[Doc Intrepid]

I actually have 2 72's a buddy is willing to give to me, but I know this won't be enough gas for 2 deep dives. I was also looking at AL80's, but I think if im going to spend the money I might as well do it right the first time. Also Doc, do you know if VAScuba rents doubles? Thanks for all the help, and if anyone is my height please tell me what your using!

Justin,

In reverse order:

- no, I don't know if VA Scuba rents doubles, call Bill at (703) 369-0098. Think that Splash may be able to rent you some, if you explain what you're looking for, call Dori or Tim at (703) 823-7680.

- we face similar issues..., remember "enough gas for 2 deep dives" means that you start your second dive with your doubles half empty (or more, depending on the length/depth of your first dive.) If you get into trouble on your second dive you may have inadequate reserve. Gas planning becomes even more important if doing this. Some divers feel its more prudent to bring two sets of 72s instead of one set of larger tanks, which allows you to start each offshore deep dive with a full set. Depends on different circumstances. How lucky do you feel? YMMV.

- you can never have too many sets of doubles. If you fill them with trimix 21/35 to do the Yancey or the Malchace, then get blown out, you either suck expensive mix in a quarry or dump the gas to refill with something else, or don't dive until you can get offshore. Better to have another set you can use to avoid wasting expensive mix. So, if your friend is willing to give you a couple 72s, take'em and have'em VIP'd, O2 cleaned, etc. For the price of a used set of bands/manifold, it's worth having another tool in the toolbox.

FWIW,

Doc

P.S. RE-read what DA and Mark just posted...its good advice. Best to find a buddy who has a set of tanks/regs you can try, and who can act as a mentor to help figure out some of the details.

 

[California Diver]

i have a set of the good ol 72s and i can get 2 long dives off them filled at 2500 psi. you can fill them even higher and get 2 longer dives off them. the rule of thrids is disreguarded though cause if im doing 2 dives they are no deco.

 

[Unproductive]

Thanks for all the advise, I think I'll get those 72's and first get use to a set of doubles and in the future maybe buy some bigger tanks.