DIR- Generic Doubles Gas Management?

[buildhuntcook]

I am newly interested in moving into back-mounted doubles and looking into the different systems. I have talked with several advanced technical as well as cave divers and I have a newby question about how the gas is managed on a set of back-mounted twin cylinders. Everyone in my local area uses a long hose configuration, i.e. GUE/UTD/ISE with a manifold. I went to a PADI shop looking into tech courses as they are the only ones that offer technical courses in my area (the advanced divers in my area were trained elsewhere) and now I am really confused about how to breathe from back-mounted doubles. From what I can gather the manifold is open all of the time and the tanks are breathed down as if they were one big tank with a really large volume. The primary regulator stays in the mouth all of the time. If there is an issue then the appropriate response to find/shut down the problem is addressed. The PADI guys I talked to described using the back-mounted doubles basically as two independent systems and requiring redundant EVERYTHING. They described breathing down each tank 500 psi and then switching regulators and leaving the manifold closed and shutting off each tank. Is this the correct method according to PADI? I feel like this defeats the purpose of the manifold being able to share gas with each regulator. The introduction of redundant everything in my mind would make it much harder to find a problem. If you have a redundant bladder in your BC and it auto-inflates then the diagnosis is more steps than knowing your bc is inflated from just your right post. I asked what they did in the event of a buddy being out of gas and having to donate if the valve was shut every time they switched and they said you turn it on. If there is an event on the regulator you are breathing from then equalizing the pressure across the manifold introduces high pressure at depth that could potentially cause more problems. Am I just way overthinking this? Is this the PADI approach to technical diving? Again I am new to this journey and I just want to feel confident about the place I am going to seek training. Any advice or experience is greatly appreciated.
Thanks in advance

 

[john120283]

Have you looked into having an instructor travel to you? A lot of the GUE instructors are willing to travel to teach classes.

I took my Fundies class locally and traveled to Vancouver Island for Tech 1

 

[formernuke]

My only options for tech training as of now are this local PADI shop(which is not looking like an option), traveling nine hours to Tennessee for a UTD instructor, or five hours for an independent TDI instructor. My local SSI shop is looking into adding XR courses but no one knows anything about them so far. Of these options what do you think would be the best course? The UTD instructor basically said to train with UTD but teach elsewhere if you are looking to be an instructor. I just want to have a solid foundation. I grew up diving in Guam and literally just got certified a month ago because I don't have access to a compressor anymore. I learned that some of the stuff I grew up with is incorrect. I understand the importance of training and being certified now. I also learned that there is a large population of divers that can't tell you how much gas they need for a dive without their air-integrated computers.

Chase the instructor not the agency, except with Tech. In tech AVOID PADI. I traveled 5 hours for my set of tech (new to tech) next round I'm going to FL. I live in MA....

What conditions do you dive in?
Ask here for recommendations on the areas you are willing to travel to.
Call and speak with those who are recommended, as stated above it's good to mesh with your instructor.

 

[buildhuntcook]

Have you looked into having an instructor travel to you? A lot of the GUE instructors are willing to travel to teach classes.

I took my Fundies class locally and traveled to Vancouver Island for Tech 1

I had not considered having an instructor travel to me. My dive buddy is the only person I have met in the area that is interested in advanced diving. I am interested in GUE and like the idea of having a unified system among your dive buddies. It is hard to convince a certified dive buddy that we should spend $1500 on a fundamentals course when we could become master divers for $1000. I understand the quality of instruction is better and the GUE course probably covers the five courses worth of material. I want to have a really solid foundation with confident and competent dive buddies, there is just not a GUE presence where I live. Do you know of an instructor that would travel?

 

[Trace Malinowski]

Before isolation manifolds, doubles were connected with a crossbar that had one outlet in the center of a fixed crossbar. A malfunction anywhere would cause a complete loss of gas.

To eliminate this risk, divers eliminated the crossbar and attached the first stages to two independent doubles that were banded together. A catastrophic loss of gas would no longer drain the entire supply. One cylinder would be left. For gas management and balance purposes, each tank was breathed down to a certain point then the diver would switch regulators.

A better method of utilizing independent doubles was to sidemount them. Sidemounting is growing in popularity because 1) It allows cave divers more versatility and access to tight spaces and tunnels. 2) It's what the cool kids do and others want to be cool.

When the isolation manifold was invented, it combined the simplicity of one large volume of gas in the cylinders with the safety of being able to close an isolator on the crossbar to create two independent cylinders with a few turns of a knob.

With the DIR philosophy, gas management is normally divided into all gas is usable, 1/2 gas is used outbound and 1/2 gas is used to return, 1/3 of the gas is used out with 1/3 used to return and 1/3 left in reserve, or 1/6 is used out with 1/6 used back and 4/6 are left in reserve. These volumes are calculated after rock bottom gas is determined. Rock bottom is the minimum amount of gas needed to get 2 divers from maximum depth to the surface in recreational diving, or to the first gas switch in technical diving, or to the surface or first stage bottle when cave diving.

In DIR diving, we leave the isolator open and breathe from the long hose coming off the right post. In an emergency, the long hose is donated from the mouth to the out-of-gas diver, and the donor switches to the backup regulator worn on a necklace with the first stage connected to the left post. The auto inflator is connected to the right post and feeds the buoyancy compensator which is a back-inflation BCD called a wing. There are a couple of advantages to having the buoyancy come off the right post related to post roll-offs and runaway BCD inflation issues. The SPG comes from the left post along with the backup reg. Again, there are a couple of advantages to having the SPG on the left including post roll-offs and stage bottle management.

There is no need for an SPG on the regulator on the right tank because if you have a problem you are going home. You've already calculated emergency gas and in an emergency, it will be there.

 

[Robert H. Diver]

I had not considered having an instructor travel to me. My dive buddy is the only person I have met in the area that is interested in advanced diving. I am interested in GUE and like the idea of having a unified system among your dive buddies. It is hard to convince a certified dive buddy that we should spend $1500 on a fundamentals course when we could become master divers for $1000. I understand the quality of instruction is better and the GUE course probably covers the five courses worth of material. I want to have a really solid foundation with confident and competent dive buddies, there is just not a GUE presence where I live. Do you know of an instructor that would travel?

The title of “master diver” doesn’t mean anything. It doesn’t open any doors like an AN/DP course would…

 

[buildhuntcook]

Chase the instructor not the agency, except with Tech. In tech AVOID PADI. I traveled 5 hours for my set of tech (new to tech) next round I'm going to FL. I live in MA....

What conditions do you dive in?
Ask here for recommendations on the areas you are willing to travel to.
Call and speak with those who are recommended, as stated above it's good to mesh with your instructor.

I currently dive freshwater lakes, springs, and quarries in the midwest. Low visibility and cold thermals. I grew up diving in Guam as I stated above. I am extremely comfortable in the water. I am pursuing wreck penetration. My wife said that if I pursue cave diving then I will be single lol(she watches a lot of crazy videos). She doesn't understand there are plenty of similarities between wreck penetration and cave diving, but that's ok with me. I will be moving to the Pacific Northwest next year so it will be a lot of cold water diving up there. I am willing to travel and invest in quality training.

 

[buildhuntcook]

Before isolation manifolds, doubles were connected with a crossbar that had one outlet in the center of a fixed crossbar. A malfunction anywhere would cause a complete loss of gas.

To eliminate this risk, divers eliminated the crossbar and attached the first stages to two independent doubles that were banded together. A catastrophic loss of gas would no longer drain the entire supply. One cylinder would be left. For gas management and balance purposes, each tank was breathed down to a certain point then the diver would switch regulators.

A better method of utilizing independent doubles was to sidemount them. Sidemounting is growing in popularity because 1) It allows cave divers more versatility and access to tight spaces and tunnels. 2) It's what the cool kids do and others want to be cool.

When the isolation manifold was invented, it combined the simplicity of one large volume of gas in the cylinders with the safety of being able to close an isolator on the crossbar to create two independent cylinders with a few turns of a knob.

With the DIR philosophy, gas management is normally divided into all gas is usable from the cylinders, half gas is used out and half gas is used back, one-third of the gas is used out with 1/3 used to return and 1/3 left in reserve, or 1/6 is used out with 1/6 used back and 4/6 are left in reserve. These volumes are calculated after rock bottom gas is determined. Rock bottom is the minimum amount of gas needed to get 2 divers from maximum depth to the surface in recreational diving, or to the first gas switch in technical diving, or to the surface or first stage bottle when cave diving.

In DIR diving, we leave the isolator open and breathe from the long hose coming off the right post. In an emergency, the long hose is donated from the mouth to the out-of-gas diver, and the donor switches to the backup regulator worn on a necklace with the first stage connected to the left post. The auto inflator is connected to the right post and feeds the buoyancy compensator which is a back-inflation BCD called a wing. There are a couple of advantages to having the buoyancy come off the right post related to post roll-offs and runaway BCD inflation issues. The SPG comes from the left post long with the backup reg. Again, there are a couple of advantages to having the SPG on the left including post roll-offs and stage bottle management.

There is no need for an SPG on the regulator on the right tank because if you have a problem you are going home. You've already calculated emergency gas and in an emergency, it will be there.

This is exactly what my understanding of the setup and use is. When I was describing it to the instructor they looked at me like I was crazy and told me I needed two spg's, two computers, redundant bladders...I just thanked them for their time and said I was looking for something a little different.

 

[grantctobin]

@buildhuntcook Assuming we’re talking about Columbia MO, there is one very local Cave 2 Tech 2 diver within a few miles of you as well as a few people within OCDA that could likely put you on a smoother path

 

[buildhuntcook]

The title of “master diver” doesn’t mean anything. It doesn’t open any doors like an AN/DP course would…

I get that. I am working towards becoming a dive guide and master diver is literally just a stop on the way to that.

 

[john120283]

Here’s the list of US based instructors:

GUE Instructors | GUE

www.gue.com

I’d reach out to a couple to see their availability and pricing.

I took Tech 1 from Guy Shockey he’s a great instructor and does travel, he might be a bit on the expensive side for a fundies instructor though as he’d have to travel from Canada.

There’s a good sized GUE community in the Pacific Northwest, especially in the Seattle area.