learning to use doubles.

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SailNaked

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My LDC has an intro to tech, (adv. nitrox deep) course that I am considering, however the instructor said there were some timed skills that needed to be done and that it was unlikely that someone new to doubles could pass it. the doubles class is about $300. seems like a lot of money to put some doubles on and swim about in a pool.

Would I be safe putting $300 into a set of doubles (+some I expect). and learning to swim about with them at the local quary? is there anyting about using doubles that is unsafe in their own right, assuming I can remember to turn them on, and get my weight right in 5ft water before jumping off a boat? I assume there is some skill to be learned with turning one on and the other off while at some depth, and then turning the other one on and using the other regulator etc. but I assume this I could learn without the class.
 
A set of doubles, even on the used market, will set you back more than $300.

If you do not have a mentor, I would recommend taking a course. Depending on the instructor and skills, $300 could be a bargain or could be way overpriced.

Here's my experience with a doubles course:
My first time in doubles - a class report

My class was absolutely worth it.
 
Do you need to know how to dive doubles to take that class, or could you take it in a single tank?

If doubles are required, that seems like a pretty shady way to set up an "intro" level course, and $300 does sound like quite a lot just to learn doubles. There are a couple dangerous things with learning doubles, though. Learning under the guidance of someone with more experience would be a good idea, even if it's not with this instructor.
 
I honestly can not see spending money on a class to learn how to dive doubles. You definitely, definitely want experience in them before taking a class though! They are not crazy difficult it just takes a little bit of time to get used to how they feel.

Strap 'em on and go swimming in shallow water just to get a feel for them. Spin around, make sure buoyancy is in check, do turns, do a barrel roll. Once you feel as comfortable in the doubles as you do a single tank then do the advanced nitrox course.
 
I didn't take a class to learn to dive them, but I did do my first couple of dives in doubles with someone who was already experienced with them, and I had read quite a bit before I did so.

The big deal with doubles is that you have introduced a lot of failure points to your configuration, but if you are prepared to deal with them as though they were a single tank (in other words, a failure means abort dive and head to the surface) then I don't see that there is any particular issue with diving them without an instructor. You might benefit from some help in getting them trimmed out (and I would HIGHLY recommend against buying tanks until you have an opportunity to dive a variety of them, unless you are in an area where only one type of tank is used -- like the double Al80's in Mexico. Doubles trim out quite differently, depending on tank type and size.) and you will almost CERTAINLY benefit from some coaching on doing valve shutdowns.
 
If you're going to practice on your own, have someone around who can save you if you turtle so you don't drown in 2 ft of water. Enter and exit the water with a reg in your mouth.
 
Can you just dive them as two singles with separate regulators? This way there is no valve twiddling to do.

With this scheme it is a matter of dealing with the weight on land and the mass/momentum underwater.

Richard
 
My LDC has an intro to tech, (adv. nitrox deep) course that I am considering, however the instructor said there were some timed skills that needed to be done and that it was unlikely that someone new to doubles could pass it. the doubles class is about $300. seems like a lot of money to put some doubles on and swim about in a pool.

Would I be safe putting $300 into a set of doubles (+some I expect). and learning to swim about with them at the local quary? is there anyting about using doubles that is unsafe in their own right, assuming I can remember to turn them on, and get my weight right in 5ft water before jumping off a boat? I assume there is some skill to be learned with turning one on and the other off while at some depth, and then turning the other one on and using the other regulator etc. but I assume this I could learn without the class.
Quite likely those timed skills are valve drills ... and unless you're built like a gibbon, they usually take a bit of practice to do smoothly.

Remember, when you need a valve manipulation it's usually because you're losing gas you had planned on having available for breathing ... so time is of the essence.

FWIW - I paid $250 for a doubles workshop a few years back, and considered it a good investment. If you're going to get into this type of diving, you need to recognize that it's not an inexpensive endeavor ... that $300 for the workshop is barely going to register on the pressures tech diving can put on your budget. If it's a well-run workshop, it's worth the money.

... Bob (Grateful Diver)
 
Quite likely those timed skills are valve drills ... and unless you're built like a gibbon, they usually take a bit of practice to do smoothly.

Also depends on the quality of the valves. Sometimes it seems as if I can just will my thermos opened and closed, whereas I have to work at my halcyons.
 
I am pretty firmly on the "doubles class is a waste of money" side of the argument - especially $300.

Other than the risk of an overloaded and off balance diver falling over backwards and not being able to get up, the risks of diving doubles are slight. In my case at least I think the turtling risk is slight as well. To date date, having dove doubles first in about 1985, I have yet to fall over backwards in them.

It does help greatly if you have a diver experienced in using doubles to mentor you as it will speed the learning curve by helping you square your configuration away and resolve the weight and trim issues that arise. However, if you read up on the subject and ask around a bit, it is no impossible, or even all that hard to learn on your own.

I do think that a set of AL80's make a decent set of starter doubles. They are not overly heavy nor overly negatively buoyant when full so they do ease the transition to doubles a lot more than say a set of double 104 or 130's. Plus when you move on to something larger, the manifold will work on other doubles with just a burst disc change, the bands will work on any 7.25" tanks, and the doubles beccome very useable stage and deco bottles so nothing goes to waste.
 
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