How to progress to twin tanks?

I'm wondering how folks progress to diving with twins. Do you take a course, or is there another way?

Will shops require to see some kind of C-card before they'll allow you to rent twin tanks?

If a course is required what is recommended?

Many technical instructors will offer an 'Intro-to-Doubles' type course. It's basically just the equipment element of entry-level technical training (minus the dive planning, deco procedures etc). Some of those courses have cards, others do not.

Shop policy on training for doubles rental is likely to be regional, or even individual to the shop.

Any of the cool kids in your area diving doubles? If they are, you should meet them. There is usualy a rec instructor or 2 smattered in a tech group that would make a great mentor for you. The single biggest mistake IMHO in advanced training is trying to master new skills in new gear all while being task loaded. Slow and easy with good technique in regard to the gear, then the rest will come alot easier.
Eric

Devon,
I keep thinking of you while watching the news about the disaster. I hope you faired well?

There is usually a reason(s) to dive using double tanks. Diving with twin tanks isn't a progression, the reason one use twins maybe a progression however there is nothing complicated or different about using a doubles rig. I use ID's when I solo or dive deep >100FSW. The doubles only give me another SPG to monitor and another 2nd stage to use, monitoring bottom times becomes more important if ones intention is to stay within the NDLs other than that singles doubles no difference, IME.

I took the GUE doubles primer when I first switched to a twinset. It was essentially a day's coaching with an instructor. If you are already in a bp/w, the jump isn't a huge one. Went over valve drills, working on trim and buoyancy and maintaining a stable platform in a twinset, as well as hose routing and why. I'm guessing other agencies intro to tech would be something similar.

I just bought some doubles and threw'em on.

You could always do the PADI Tec Basics course?

Doubles are not hard to master at all. If you already have the skills to keep yourself stable, then a dive or 2 with doubles should allow to get use to them. I know a few recreational divers who use doubles just for their own reasons such as not having to change out, and extra gas and regs. Now there is a downside. You cannot move as nimble as you used to, you cannot turn sharply and look behind you as easily, and depending on tanks, they could be heavier than heck and take a toll on your back.

How I began with doubles :
- purchased doubles
- made some little adjustments on my wing
- dove
- dove
- dove
- you know what ?
- dove
- i don't have a c-card

KD8NPB:

I just bought some doubles and threw'em on.

You could always do the PADI Tec Basics course?

Click to expand...

As KD said, there's nothing special about adding doubles to your kit. However, everything else will change as a result....

You will probably find them more comfortable and balanced than your single. However, the thing you might find different is your wing set up. If you are currently diving a jacket-style BCD, you will want to move to a wing, and one that is sufficiently large for the doubles. I don't know if you dive wet or dry, but if wet, you should consider a double bladder wing, so you have some redundancy on your "floaty bits".

If you are currently diving a wing, and it's big enough, all you need to do is recalculate your buoyancy, rig your regs and away you go. As mentioned, hooking up with someone who is diving doubles now will be helpful in terms of sorting out hose routing. If you Google "DIR hose routing" you'll find lots of information. You should be aware that not all first-stages are equal when it comes to routing. Again, there's several discussions about that topic on here. You will possibly need to get some longer hoses as well.

The only other thing to consider is your reasons for going to doubles. If you aren't diving DIN now, you should allow for that eventuality when you are buying regs and manifolds. It's a much safer system, and as you move towards "the dark side" DIN becomes mandatory.

Just be aware that doubles, like four-wheel drive, allow you get into all sorts of trouble that you might not be able to otherwise. It's pretty hard to mess up too badly on a single 80, but that isn't the case. I own three sets of various sizes, but my bigguns (HP 130s) pretty much allow me to sit at the bottom of a lake for a weekend.

And one final thing, doubles are heavy to schlepp around. You might want to at least look at the side-mount option. My wing is about done, and before I replace it, I'm going to consider that... But then I am old and frail.

It's important to understand how a manifold works, and how the gas routes through it, because it impacts how you solve problems.

You can put on a set of doubles and go diving, without being able to reach your valves or do anything with them, but in effect, you are diving a big single tank with a lot more failure points. To make use of the redundancy that doubles offer, you have to be able to reach and close valves. This takes most people some practice time.

Another thing to know about doubles is that they tend to be head-heavy, and almost everybody who transitions to doubles will immediately start diving in a head-up position. That sentence may not make a lot of sense, but when you are head-heavy, you rear up to shorten the lever arm that the weight at the top of your body has to act through. Many people pile weight up high to try to solve the issue, which makes it worse. In addition, doubles are a bit idiosyncratic -- what trims out well on me at 5'4" may not trim out well on you if you are 6'2", and vice versa. Good idea to try tanks before you buy them. I bought 72s to begin with, thinking they would suit me because they were small, and I can't trim the things out to save my soul. First dive in a set of 85s and I felt like I had come home.

I did my transition with some mentoring and feedback from my buddies. It wasn't really that difficult.