Twin cylinders??

[kemahdiver]

After taking/implementing all the tips and strategies for efficiently consuming air, I have concluded that I just suck a lot of air. Dive trips are frustrating because I have to terminate my dives much earlier than the rest of the group.
This has led me to believe the best fix is to dive with two tanks. However, during the relatively few dives that I have been on, I have never seen anyone diving with two tanks nor have I heard any dive shops suggest/offer twin tank capabilities.
So my question for the operators and experienced divers out there is: How foolish is the thought of diving each dive with a two-tank set up? Too impractical?

All thoughts, pros and cons, are appreciated.

Info. gathered here will likely drive my new BC purchase in a couple weeks. Looking at the Zeagle Ranger (twin-cylinder capable) or the Zeagle Halo (jacket style which I still prefer).

Thoughts on these BCs also welcomed.

Thanks to all in advance for your input

J.R.

 

[Akimbo]

Is your objective to have enough capacity to more or less match other diver's bottom time or exceed it with reserve capacity? Also, how much weight do you think you can comfortably pack. For example, would a 30% larger single do what you want or are you also after the backup offered by dual regulators? There's lots of options.

 

[decompression]

If you are traveling sourcing a double tank set up can be challenging not to mention difficult on your average recreational dive boat.

By your profile, you are very early in your dive career.....time/experience more than likely help with your consumption.

There are many ways to reduce your SAC rate, proper weighting, trim, propulsion and streamlining of gear.

I know of a couple of courses that focus on the things are are guaranteed to reduce your SAC. Much easier that dragging along 2 sets of doubles on a 80' Cozumel dive.

 

[azstinger11]

What size tanks are you using when you do your dives? I'm guessing standard AL 80s? If that's the case see if you can rent something like a steel HP100 or HP120 size tank and see how that goes? If you are using a standard AL80 tank you have approximately 78 cubic feet of air, if you go to a steel 120 that number goes to 122(ish) cubic feet.

One thing about the twins, if you dive a boat without a compressor then you'd have to have twin sets = to the number of dives you wanted if you are saying you actually need twins to complete the dive. So if you are doing a 3 tank boat dive with no compressor, you'd have to have 3x twinsets for 6 tanks total. Thats a) a lot of money and b) taking up a TON of room on a dive boat. Also if you dive nitrox you'd basically need another set of everything to accommodate stuff being NITROX capable so, even more tanks/$$.

I'm not against twinsets, but it feels like a rash decision at this point.

If you are committed to the twin tank idea, I believe the general consensus around here will be to skip a traditional BCD and do a backplate/wing setup. Though I think for a BCD people tend to like the ranger.

I'm an air hog, my wife on the other hand I think is part mermaid. When he get back on the dive boats i'll be 300-450PSI(ish) and she is routinely north of 1500(ish) PSI, just something that happens.She has a few girls only dive trips and if I didn't know better based on their bottom times I'd say they were doing rebreather dives, freaking mermaids I tell ya! Am I personally frustrated that I use air quicker yup, sure am. However, it's not something I can impact too much and just the way diving works. I've just learned to accept it, I do everything I can to stay calm and just enjoy my dive. From when I started to diving to now, I have had a very slow but steady reduction in my air used so just keep diving and enjoy your time underwater!

 

[Stoo]

In this part of the world, twin tanks are extremely common, but not readily available to rent. As others have pointed out, you may find that your consumption will improve dramatically over time. But, some people just seem to consume more air than others. A young, relatively inexperienced (130 dives) I dive with is one of those people. She fairly small in stature, is extremely fit, and yet she consumes air as a rate that's easily 50% greater than Mrs. Stoo, who is tiny, and reasonably fit. Our friend (at my urging) acquired a steel LP 95 which really helps, although it doesn't do much to when we are away and using rental gear.

Similarly, I spent a week diving in BC recently and one of the people in my group was a very large man... 6'7" and overweight and a fairly new diver (about 100 dives). He adopted side mount early on just to have a fighting chance of staying down. This is certainly an option for the travelling diver... you supply the harness, regs, cam bands etc, and all you need are the tanks.

Having said that, it was my opinion that this large guy was diving with way too much lead. (Bear in mind that diving in BC is cold and salty so lots of lead is standard), but over the couse of the week, he dropped 14 pounds of lead, and I believe he was still over-weighted.

It might be worth spending some time diving one-on-one with a very experienced DM or Instructor (perhaps on your next trip) to see if your dive technique can be improved. In my experience, many Instructors train their divers to wear too much lead (because it's easier to descend etc.) but it's a bad habit. Improper buoyancy leads to a plethora of problems, all of which can impact air consumption.

Just an afterthought... side-mount diving adds another level of complexity to your diving. I am not suggesting you jump right into this before "mastering" single, back-mount.

 

[RyanT]

@azstinger11's advice is spot on. A set of doubles would be great to extend your gas supply on a single dive. But if you want to do two or more recreational dives in a day, you'll need another set of doubles. A set of doubles is EXPENSIVE and most recreational dive boats won't let you bring two sets of doubles anyway. Depending on what you're diving now (AL 80?), I would consider just buying a couple of steel 108's or 117's. It'll be cheaper than doubles, give you more gas, and you'll shed some lead if you've been diving Al 80s.

A backplate/wing set up with a single tank adapter (STA) will allow you to dive singles now and swap out to doubles later if you want without having to switch out your entire BC.

 

[RyanT]

Oh yeah, and on the steel tank front, you have quite a few options. 100 cf are great tanks and similar in size to Al 80s. The LP 108s are larger in size, and many shops will overfill them, giving you somewhere in the neighborhood of 120 cf. The HP 117s will give you a nice bit of gas filled to their nominal rating. Both the 108 & 117s are thicker tanks (8" in diameter compared to 7.25" for Al 80s). The HP 120's are slimmer tanks (same diameter as Al 80), but are long. They really tend to be too long for divers under 6'.

 

[PfcAJ]

Just go dive a lot and don't worry about your sac rate. It'll come down with time. You're not special. Everyone starts like this.

Work on being relaxed, neutral, properly weighted, streamlined, and efficient in your movement. Before you know it your sac will be as low or lower than everyone else.

 

[2airishuman]

After taking/implementing all the tips and strategies for efficiently consuming air, I have concluded that I just suck a lot of air. Dive trips are frustrating because I have to terminate my dives much earlier than the rest of the group.

Been there, lived that. My air consumption has improved somewhat but I have a higher basal metabolic rate than most people, due to muscle mass, and I'm always going to use more air.

How foolish is the thought of diving each dive with a two-tank set up? Too impractical?

All thoughts, pros and cons, are appreciated.

Here's what I do:

- For local dives where I can bring my own cylinders, I typically dive a single HP120. That gives me slightly more run time than most people with AL80s.
- On local dives where that isn't enough air or where I'll be diving solo at depths greater than about 25 feet, I dive a twinset. I have one pair of LP72 twins, and two pairs of HP100 twins, and I have the parts to make up an HP120 twinset from my fleet of HP120 singles.
- While traveling I seek out operators who offer larger cylinders. For example, in Cozumel I use Aldora, who offer HP120s, and in the keys Conch republic offers HP100s. Most operators have at least something larger than an AL80 they will let you use if you ask, but too often it's an AL100 that is short filled to 90 cf, and that's not enough for me to keep up with most divers.

To be clear, when I'm speaking of a twinset, I'm talking about manifolded, banded doubles, that attach to the BC with two bolts.

My BC will allow me to dive independent doubles, which can be mounted ad hoc using cam bands. I've done this experimentally. Since there is no manifold, you have to switch back and forth between regulators, and have two SPGs. I might try it if I want to make a long dive in some place where AL80s are the only thing available.

While I have not asked, it is my perception that few dive boats will permit doubles unless you are on a trip that mainly caters to technical divers, and have a technical certification of some kind. They complicate cylinder handling and tend to lead to longer dives that complicate scheduling.

Info. gathered here will likely drive my new BC purchase in a couple weeks. Looking at the Zeagle Ranger (twin-cylinder capable) or the Zeagle Halo (jacket style which I still prefer).

Thoughts on these BCs also welcomed.

I dive a DSS backplate and wing. I have separate wings for singles and doubles. I believe this is the most common arrangement for people who dive twins.

 

[Schwob]

Well, I have the same predicament.
No real help here, just comiserating...(is that a real word?)

I did a brief try SM dive and preliminarily find it not that complicating for just OW diving. But it does complicate cylinder selection if you want to keep al avenues open. E.g.: that nice HP 120 that would let me stay withh my son on an AL80 is nice for single BM and will work great if and when I get into doubles BM. Heavy beast then but nice.
But then why HP120s and not HP133s? The latter seem to make more sense as long dive nitroc singles with ponies and I don't see why they would be worth as doubles in significant ways.

But I hear / read that neither is not a good choice for SM at least for most (don't really know so - yet).
It seems there is a consensus (my not yet fully formed interpretation) that LPs like 95s especially, maybe also 108s seem to be a great choce across the board for mid to large size people if you can get cave fills. But I have don't want to go there if I can't get cave fills where I live. Since it's big bucks I have not decided yet, am "waiting" on this and maybe wait until I can try a little more of this and that first or get hit by devine insight or money that just wants to be spent...

I've slung (as a test) an AL 80 as a pony (just like a stage) instead of a 40 (or 20, pending five / destination) with an AL80 for back gas and made 1/3 ish of it part of the dive plan (switching more than once). That works fine, maybe less than SM for diving into a current but it works, but I might as well SM then... I think...

Anyway if I want to plan for vacation dives where I will be stuck with AL 80s (or where that is just convenient and all I want is the functionality and duty of a pony AND 40% more gas than e.g. my son on deeper rec. dives and say 30% more on shallower ones (which go long enough he won't mind if It's shortened by 5 minutes. I think I can work that out with 3 AL 80s... One serving as the Pony AND part of the gas plan for both dives with 1000 to 1200 PSI planned to be taken out of it the first (deeper) dive (rest is contingency only for that dive) and then between 800 and 1000 PSI to be taken from it (pending what was taken out the first) during the shallower second dive and 1kpsi staying in for contingency (775 PSI in a 77.4 cuft AL 80 is the same gas as 3000 PSI in an AL 19 certainly enough contingency for the shallower dive (did the math for me)).
So in that case I would need to bring 3 tanks for a two dive boat trip or a two dive shore dive trip (pre refill) (of course 4 won't hurt if an ootion). same diffetence if SM or slung "managed pony" (or independent doubles for that matter).

But I am still undecided what to really get for "home" to leave all avenues for future dive options open, including large capacity single plus pony. Despite thinking about it I am somewhat clueless actually.

Maybe that's a good sign that presently the want outweighs the need...

But to go on boat trips near home I need to buy or rent something and I am not thinking buying more AL 80s to fully emulate vacation mode is the right thing (cold water at home)...

One thing is for sure: The AL100s you can rent / get in many warm water destinations are a bit problematic in that (at least Luxfer S100s) they hold 100cf at 3300 PSI , but so far I have only gotten them filled to around 3000PSI, because that's what "they" run at for their auto shutoffs and "they" dont want to change their setting (was told that even at Rainbow Reef, really dislike to beg...) or flat out deny that 3300 PSI and not 3000 is "full", so they in practise for me so far are just a 10% boost... ... slightly better actually than the HP100 an LOB last year would just not fill to north of 3000PSI, feigning ignorance and insisting on it being full at 3000PSI, not 3400PSI...
Live and learn...