DIR- Generic Learning Doubles (in Wetsuit?)

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The Cosmicist

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Location
47°9′S 123°43′W
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Hello everyone, posting here because I recently got a Rec Pass in Fundies and I would like to learn (backmount) doubles in GUE style. I only own a wetsuit and don't currently have the money for a drysuit, so I have a couple of questions regarding how to learn doubles right now.

1. Are there problems with learning doubles while diving wet? I'm unsure of weighting considerations, although I can do some quick math in my head. I know this will depend on which cylinders are on my back and their buoyancy characteristics. For reference though, in Fundies I dived:
-in fresh water
-5mm suit with 6mm booties and 3mm hood
-single LP72 (not sure why they gave us those)
-Alu plate
-4lbs of weight

2. What cylinders are most recommended for normal backmount doubles? I understand this will depend on what diving I am doing/will do. I currently do a mix of ocean and FL springs diving at the recreational level, but my goals are to cave and mine dive (primarily), and also to dive wrecks. I don't care about weight on land, etc. I want to learn what is common/useful to cave diving (and secondarily, wreck diving)... I seem to see LP85s and HP100s mentioned here a lot. A follow up to this would be, what should I take into consideration when buying my own set of doubles?

3. How valuable is the GUE Doubles Primer class? I live in Savannah, GA and don't know anyone here (outside of an SDI shop and a couple NAUI instructors) that could teach me doubles and dive with me. I'm new to diving and haven't developed a base of friends and contacts, so the course seems beneficial in that sense.


Thanks for the advice!
 
Many of us that had never heard that diving twin tanks in a wetsuit is dangerous or something
have been diving twin tanks in a wetsuit and in caves with the Faber 12.2L 232bar cyl the go to
forever.
 
With a wetsuit, I would reccomend diving double AL80s as they are near neutral and easy to swim up in case of a BC failure. LP85s and HP100s will be substantially more negative.

The doubles primer is a great intro to diving them. Savannah is only a few hours from cave country where there are numerous instructors who more than dabble in doubles.
 
It's very useful to have someone help you learn the valve drill. It's described in detail if you are a GUE member and there are youtube videos IIRC, but doing it right is important and there are a decent number of steps. Doesn't have to be a GUE instructor, but they need to be an active GUE tech diver if not. It's also helpful to have someone watching to stop you when you skip a step and try to turn off all your air doing a valve drill. And yes, you probably will do that at least once.
 
Frankly I do not understand well what you mean with "learning doubles".
There is nothing special to learn using a twin tank of proper size when doing a recreational dive in a wet suit.
The only technical difference is how to attach the BCD to the tank. But this is a not-issue if you have a backpack + wing...
Once the tank(s) are behind your shoulders, you hardly have any effect.
Of course, whenever you change the tank(s) (different capacity, alu vs steel) you need to adjust the number and position of weights. That's all.
For me, switching from my standard 15-liters steel to an Al80 is much more troublesome than switching to an 8+8 liters steel twin tank.
Generally speaking, for a given capacity, two small tanks result in a rig which is more compact, better balanced and easier to use than the single large tank.
When I started diving, students were given twin tanks, as they were considered "easier". Typically 10+10 liters steel at 150 bar (3000 liters total). They were light, almost neutral, and well balanced.
The usage of a 15 liter steel at 200 bar, as my current one, was considered more difficult, as the tank is negative buoayant, more bulky, and the two separate valves are more distant and more difficult to operate.
Conclusion: rent your twin tanks (of proper size, not too big) and go diving. You will love them...
They went out of fashion for training new divers just because they are more expensive than a crap AL80, not because they are more difficult to use
 
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For Florida cave diving in GUE land, you’re going to want lp104s or hp130s (3442psi). 55-60lb wing. Drysuit required.

Florida wrecks, al80s with wetsuit or double hp100s. 85s are a pain because none of the south Florida shops properly fill lp steels. 40ish lb wing. Drysuit needed for the steels.

Acquire a drysuit. If you’re a stock size (or close to it), there’s always affordable suits on the used markets.
 
1. Are there problems with learning doubles while diving wet? I'm unsure of weighting considerations, although I can do some quick math in my head. I know this will depend on which cylinders are on my back and their buoyancy characteristics. For reference though, in Fundies I dived:
-in fresh water
-5mm suit with 6mm booties and 3mm hood
-single LP72 (not sure why they gave us those)
-Alu plate
-4lbs of weight
Last June I got my GUE-F rec pass on doubles and canister light with a 3mm wetsuit, if that answers your question. I used alu80s because for 104s a drysuit is highly recommended.

Also I came very close to a tec pass, so you can even get a tec pass in a wetsuit.
2. What cylinders are most recommended for normal backmount doubles? I understand this will depend on what diving I am doing/will do. I currently do a mix of ocean and FL springs diving at the recreational level, but my goals are to cave and mine dive (primarily), and also to dive wrecks. I don't care about weight on land, etc. I want to learn what is common/useful to cave diving (and secondarily, wreck diving)... I seem to see LP85s and HP100s mentioned here a lot. A follow up to this would be, what should I take into consideration when buying my own set of doubles?
Alu80s as other said.
3. How valuable is the GUE Doubles Primer class? I live in Savannah, GA and don't know anyone here (outside of an SDI shop and a couple NAUI instructors) that could teach me doubles and dive with me. I'm new to diving and haven't developed a base of friends and contacts, so the course seems beneficial in that sense.
It's a GUE class so I am confident is very valuable. Though, I learned to dive with doubles for the first time during my Fundies and at least for me it worked great. Not sure if the Doubes Primer is necessary.

P/S: I don't concider myself a good diver and for sure I sucked big time before GUE-F.
 
Frankly I do not understand well what you mean with "learning doubles".
There is nothing special to learn using a twin tank of proper size when doing a recreational dive in a wet suit.
This is 100% wrong. There are a ton of nuances to diving doubles. Let's ignore the obvious such as proper use of a long hose in an OOA situation. You need to understand how to properly size your harness, where your plate should lay on your back, how to adjust band heighths, how to adjust all of those things in order to trim out properly, and how to do valve drills effectively. The fitting of the bp/w and harness seems easy, but I've seen more people turtling, flipping feet over head, and just generally unsteady all because they're not properly fitted.
I learned to dive doubles from a mentor 15 years ago. 2 years ago I took GUE fundies. I thought I was pretty well versed in all of the things I mentioned above. On day 1, I realized I was wrong. I wish in retrospect I had taken some proper instruction on diving doubles. I hated doubles for many years and preferred sidemount, all because I had no idea my harness and doubles weren't set up properly.
 
This is 100% wrong. There are a ton of nuances to diving doubles. Let's ignore the obvious such as proper use of a long hose in an OOA situation. You need to understand how to properly size your harness, where your plate should lay on your back, how to adjust band heighths, how to adjust all of those things in order to trim out properly, and how to do valve drills effectively. The fitting of the bp/w and harness seems easy, but I've seen more people turtling, flipping feet over head, and just generally unsteady all because they're not properly fitted.
I learned to dive doubles from a mentor 15 years ago. 2 years ago I took GUE fundies. I thought I was pretty well versed in all of the things I mentioned above. On day 1, I realized I was wrong. I wish in retrospect I had taken some proper instruction on diving doubles. I hated doubles for many years and preferred sidemount, all because I had no idea my harness and doubles weren't set up properly.
Disagree on learning to adjust band height. People should leave them alone where they go. Most issues I see with people being unable to reach valves are from people mucking with their band height. The rest are incorrectly adjusted harnesses. Very few are actually true mobility issues.

The rest, spot on.
 
https://www.shearwater.com/products/peregrine/
http://cavediveflorida.com/Rum_House.htm

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