Twin cylinders??

[KevinNM]

As someone else has said: twindies are the best option for travel if you go down that route. It's just twin independent singles.

Scubapro make something call a bibo which can attach the cylinders together. Although I've never tried it so can't say it it's any good.

You could also install lola vales and manifold. Have no idea how freaked out the shop would be when you do that....

 

[NAM001]

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.

I would say foolish. Many operators will say only single tank diving. doubles screws their planning up big time. Just go for a bigger tank and offset the symptom.

The logistics of doubles are just not worth the hastle. wet suits are fine for singles. you loose a BC and you drop weight and you can power up. but the doubles now makes that stratagy a bit difficult. Your suit and BC off set the tank and lead. now you have 2 tanks (anonther -10# perhaps) depending on whether they are al or steel. Often you will hear that if you dive doubles you need to do it in a dry suit, Again many warm water ops say no to dry suits. (potential flooding issues) I am speaking from gulf/ carribean dives. I would just ask for a steel 100 to dive with when the others are diving with al 80's The reason why is that. (very crude and innaccurate explanion) an al80 will give you 60 cuft to use . (80-20) the 20 is the 700# you get back on board with. a steel 100 gives you that back so you have a 30+% increase of usable air and still have 5-700# surfacing psi. that can offset a lot of bad sac. woth that you can have a .9 sac and keep up with those that have a .6 sac..... if you use a lp 120 for instance the full bouyancy is about -10 only about 6 heavier than the al 80 or equivilant to twin al80's air availability wise. I use lp95's and they are 85-77= 13 cuft larger than an al80 (al80 is only 77) and if they over fill them (accidentally) to 3000 you have shy of 110 cuft and only maybe 2# heavier and less bouyant. 108 cuft compared to 77 cuft is a lot more gas. here is the math getting onboard with 20 cuft. 77 vs 108 is now 57 vs 88 usable cuft or roughly 60 vs 90 or 50% more.

 

[george_austin]

No - you get to a certain point and you will go through MORE air with higher capacity tanks - especially twins. Just keep diving and work on relaxing and exhaling almost completely. You may be breathing off the top of your lungs and not getting rid of abnormal amounts of C02 in your blood which just triggers another breathing cycle

 

[divezonescuba]

Pm sent.

We use bm doubles all the time on our boat. Not a big deal for us, although we really need to raise our tank brackets a bit so that they can fit on the rack like all the single tanks.

 

[Akimbo]

Many operators will say only single tank diving. doubles screws their planning up big time. Just go for a bigger tank and offset the symptom.

Although generally true, I have seen exceptions made based on one or more of the following reasons

• physically large divers that can easily pack the weight
• those that make the case for large reserves for buddy obligations
• explain that their consumption rate is high
• concern over elevated CO2 buildup to justifying high consumption
• convince them that they will exit the water with the majority, DM, etc
• will stay within NDLs

The biggest problem I have seen are are boats with benches that don't accommodate doubles, rebreathers, and sidemount well. Definitely check in advance.

Edit: The standard tank racks on the very popular Newton dive boats are not doubles friendly.

 

[kemahdiver]

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.

Thanks for the reply. Objective is to have enough capacity to complete the dive with my daughter and the group. Weight of two tanks won't be a problem. I don't know if a 30% larger single would do what I want. I just know the operators I've dove with all use the smaller aluminum 80s. Maybe I just need to find different operators? thanks again for the reply.

 

[kemahdiver]

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.

Thanks Jay for the reply. More time should definitely help, just not sure how much it will help. I believe my weight, trim, etc. is fairly efficient now. At least efficient enough that doubling my dive time is not likely just through the minor adjustments that might still exist.
Maybe I should learn more about what is involved with sourcing a double tank set up. Based on the responses, it is more than just strapping on a second tank and reg. Again, thanks for the response.

 

[kemahdiver]

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!

Azstinger- Wichita?? -my wife was born and raised there and daughter born there as well. Anyway, thanks for the reply. All have been AL 80s. I'll start looking for operators with the larger steel tanks to rent. Maybe that extra will be just enough to make the difference. Your information is exactly what I was needing to know. Sounds like too much trouble to mess with. My daughter is like your wife...I think she somehow makes air when she dives. Like you and others have said, I just should accept it, dive more and be patient.

 

[Steve_C]

@azstinger11' most recreational dive boats won't let you bring two sets of doubles anyway. I would consider just buying a couple of steel 108's or 117's. .

+1

 

[kemahdiver]

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.

Thanks Stoo for the great information. Seems like some one-on-one critiquing or one of the classes Azstinger mentioned is the most reasonable next step. Maybe I am not as streamlined or efficient as I think.