Single tank: One 1st Stage or Two?

WhatAKeepah · August 19th, 2006, 03:53 AM

The following is a quote from Part Two of [A HREF="http://www.direxplorers.com/dir-tech-diving/2267-doing-right.html"]THIS POST[/A]

Quote: (Originally Posted by peter_steinhoff)

If we look at consistency in equipment configuration everything looks the same with different layers of complexity. A single tank diver has a backplate, wing, longhose, backup reg, one first stage/tank. A double tank diver has the same rig except two first stages and canister light. A more advanced diver would add a number of stage bottles and deco bottles and perhaps a scooter or two. An even more advanced dive would use a rebreather placed between the regular doubles and add the rebreather mouthpiece and switchblock to a regular doubles setup.

So, which is the more accepted setup for a beginning diver [actively (read: desprately) seeking DIR-F] diving a single tank. One 1st stage or Two? I figured it makes more sense to get "used" to having two 1st stages with all the associated cable routing, etc...

Thoughts, advice?

-Alex

MonkSeal · August 19th, 2006, 02:41 PM

Quote: (Originally Posted by WhatAKeepah)

The following is a quote from Part Two of [A HREF="http://www.direxplorers.com/dir-tech-diving/2267-doing-right.html"]THIS POST[/A]

So, which is the more accepted setup for a beginning diver [actively (read: desprately) seeking DIR-F] diving a single tank. One 1st stage or Two? I figured it makes more sense to get "used" to having two 1st stages with all the associated cable routing, etc...

Thoughts, advice?

-Alex

Concepts of MGR (minimum gas reserve) and MDL (minimum deco limit) as well as MOD for nitrox 32 define dives that can be conducted with single tank. From that perspective it looks that gas sharing within team is enough redundancy for 1st stage failures. IMO one 1st stage follows DIR path of minimalistic approach.

Regarding "desperately seeking DIR-F" you can contact any of four Italians from http://www.gue.com/Training/Instructors/index.html

steve_cooper71 · August 20th, 2006, 11:17 AM

I've wondered about this one myself, in the end I opted for an H valve on my single mainly because it makes changing between doubles and singles a lot simpler. What I have inferred whether rightly or wrongly is that double valves shouldn't be seen as giving some sort of redundancy that would perhaps have people pushing the limits of a single tank? For my part its about convenience but I believe there's also an issue of regulator performance if you have an OOG situation, it's surely better to have each reg of an independent 1st stage if you can?

steve.

Quote: (Originally Posted by WhatAKeepah)

The following is a quote from Part Two of [A HREF="http://www.direxplorers.com/dir-tech-diving/2267-doing-right.html"]THIS POST[/A]

So, which is the more accepted setup for a beginning diver [actively (read: desprately) seeking DIR-F] diving a single tank. One 1st stage or Two? I figured it makes more sense to get "used" to having two 1st stages with all the associated cable routing, etc...

Thoughts, advice?

-Alex

MonkSeal · August 20th, 2006, 05:17 PM

Quote: (Originally Posted by steve_cooper71)

I've wondered about this one myself, in the end I opted for an H valve on my single mainly because it makes changing between doubles and singles a lot simpler. What I have inferred whether rightly or wrongly is that double valves shouldn't be seen as giving some sort of redundancy that would perhaps have people pushing the limits of a single tank? For my part its about convenience but I believe there's also an issue of regulator performance if you have an OOG situation, it's surely better to have each reg of an independent 1st stage if you can?

steve.

I'm not sure about performance issue, maybe there's higher possibility of freezing in cold water due to increased flow. However, if you have H valve then it's definitely better to have two 1st stages because that eliminates possibility on unintentional roll-off of valve that doesn't have 1st stage attached to.

WhatAKeepah · August 23rd, 2006, 09:19 AM

OK, I just received copy of Doing It Right: The Fundamentals of Better Diving, and on page 81 JJ states that, "...single tank divers who choose to dive in deeper areas or in overhead environments must adhere to equipment redundancy, and use a "Y" or "H" valve to allow two first stages to be affixed to a single tank." [emphasis added].

As my typical dives are in the 30-35m range, I would say that this is appropriate for me.

Quote: (Originally Posted by MonkSeal)

Regarding "desperately seeking DIR-F" you can contact any of four Italians from http://www.gue.com/Training/Instructors/index.html

I'm actually waiting on an instructor to find two more people to get a class together soon. Worst case scenario, I'll do it in Florida when I take leave in December...I was just planning on doing Adv Nitrox/Decom while I was there instead...oh well...

Jonathan · August 23rd, 2006, 10:36 AM

Quote: (Originally Posted by WhatAKeepah)

OK, I just received copy of Doing It Right: The Fundamentals of Better Diving, and on page 81 JJ states that, "...single tank divers who choose to dive in deeper areas or in overhead environments must adhere to equipment redundancy, and use a "Y" or "H" valve to allow two first stages to be affixed to a single tank." [emphasis added].

As my typical dives are in the 30-35m range, I would say that this is appropriate for me.

As MonkSeal says, it's generally the case that you use single tank, single first stage to ~30m and if you need additional redundancy then go straight for twin 12ls.

Quote: (Originally Posted by WhatAKeepah)

I'm actually waiting on an instructor to find two more people to get a class together soon. Worst case scenario, I'll do it in Florida when I take leave in December...I was just planning on doing Adv Nitrox/Decom while I was there instead...oh well...

Also keep an eye on here as a space may come up on one of the UK courses

Cheers

J

MonkSeal · August 23rd, 2006, 10:40 AM

Quote: (Originally Posted by WhatAKeepah)

...in overhead environments...

For me overhead equals doubles and of course 2 1st stages and manifold.

WhatAKeepah · August 23rd, 2006, 01:50 PM

Quote: (Originally Posted by MonkSeal)

For me overhead equals doubles and of course 2 1st stages and manifold.

No argument here. Thanks all for your input on this.

- Alex

Chrisch · August 23rd, 2006, 03:03 PM

Quote: (Originally Posted by steve_cooper71)

..in the end I opted for an H valve on my single mainly because it makes changing between doubles and singles a lot simpler. ...

Me too.

Oddly enough in France an instructor is required by law to have a two outlet tank, but there is no requirement for two 1st stages....

Chris

MonkSeal · August 23rd, 2006, 03:12 PM

Quote: (Originally Posted by Chrisch)

Me too.

Oddly enough in France an instructor is required by law to have a two outlet tank, but there is no requirement for two 1st stages....

Chris

... which can lead to very dangerous situation: the post without 1st stucked in on position - instant loss of gas.

August 19th, 2006, 03:53 AM	#1 (permalink)
WhatAKeepah(Offline) New Member Join Date: Jul 2006 Location: La Maddalena, Italy Posts: 26	Single tank: One 1st Stage or Two? The following is a quote from Part Two of [A HREF="http://www.direxplorers.com/dir-tech-diving/2267-doing-right.html"]THIS POST[/A] Quote: (Originally Posted by peter_steinhoff) If we look at consistency in equipment configuration everything looks the same with different layers of complexity. A single tank diver has a backplate, wing, longhose, backup reg, one first stage/tank. A double tank diver has the same rig except two first stages and canister light. A more advanced diver would add a number of stage bottles and deco bottles and perhaps a scooter or two. An even more advanced dive would use a rebreather placed between the regular doubles and add the rebreather mouthpiece and switchblock to a regular doubles setup. So, which is the more accepted setup for a beginning diver [actively (read: desprately) seeking DIR-F] diving a single tank. One 1st stage or Two? I figured it makes more sense to get "used" to having two 1st stages with all the associated cable routing, etc... Thoughts, advice? -Alex

August 23rd, 2006, 09:19 AM	#5 (permalink)
WhatAKeepah(Offline) New Member Join Date: Jul 2006 Location: La Maddalena, Italy Posts: 26	OK, I just received copy of Doing It Right: The Fundamentals of Better Diving, and on page 81 JJ states that, "...single tank divers who choose to dive in deeper areas or in overhead environments must adhere to equipment redundancy, and use a "Y" or "H" valve to allow two first stages to be affixed to a single tank." [emphasis added]. As my typical dives are in the 30-35m range, I would say that this is appropriate for me. Quote: (Originally Posted by MonkSeal) Regarding "desperately seeking DIR-F" you can contact any of four Italians from http://www.gue.com/Training/Instructors/index.html I'm actually waiting on an instructor to find two more people to get a class together soon. Worst case scenario, I'll do it in Florida when I take leave in December...I was just planning on doing Adv Nitrox/Decom while I was there instead...oh well... Last edited by WhatAKeepah; August 23rd, 2006 at 09:34 AM. Reason: To add more information

August 19th, 2006, 02:41 PM	#2 (permalink)
MonkSeal(Offline) Old Member Join Date: Feb 2006 Location: Zagreb, Croatia Posts: 474	Quote: (Originally Posted by WhatAKeepah) The following is a quote from Part Two of [A HREF="http://www.direxplorers.com/dir-tech-diving/2267-doing-right.html"]THIS POST[/A] So, which is the more accepted setup for a beginning diver [actively (read: desprately) seeking DIR-F] diving a single tank. One 1st stage or Two? I figured it makes more sense to get "used" to having two 1st stages with all the associated cable routing, etc... Thoughts, advice? -Alex Concepts of MGR (minimum gas reserve) and MDL (minimum deco limit) as well as MOD for nitrox 32 define dives that can be conducted with single tank. From that perspective it looks that gas sharing within team is enough redundancy for 1st stage failures. IMO one 1st stage follows DIR path of minimalistic approach. Regarding "desperately seeking DIR-F" you can contact any of four Italians from http://www.gue.com/Training/Instructors/index.html

August 20th, 2006, 11:17 AM	#3 (permalink)
steve_cooper71(Offline) New Member Join Date: Jul 2006 Location: Northern Ireland Posts: 41	I've wondered about this one myself, in the end I opted for an H valve on my single mainly because it makes changing between doubles and singles a lot simpler. What I have inferred whether rightly or wrongly is that double valves shouldn't be seen as giving some sort of redundancy that would perhaps have people pushing the limits of a single tank? For my part its about convenience but I believe there's also an issue of regulator performance if you have an OOG situation, it's surely better to have each reg of an independent 1st stage if you can? steve. Quote: (Originally Posted by WhatAKeepah) The following is a quote from Part Two of [A HREF="http://www.direxplorers.com/dir-tech-diving/2267-doing-right.html"]THIS POST[/A] So, which is the more accepted setup for a beginning diver [actively (read: desprately) seeking DIR-F] diving a single tank. One 1st stage or Two? I figured it makes more sense to get "used" to having two 1st stages with all the associated cable routing, etc... Thoughts, advice? -Alex

August 20th, 2006, 05:17 PM	#4 (permalink)
MonkSeal(Offline) Old Member Join Date: Feb 2006 Location: Zagreb, Croatia Posts: 474	Quote: (Originally Posted by steve_cooper71) I've wondered about this one myself, in the end I opted for an H valve on my single mainly because it makes changing between doubles and singles a lot simpler. What I have inferred whether rightly or wrongly is that double valves shouldn't be seen as giving some sort of redundancy that would perhaps have people pushing the limits of a single tank? For my part its about convenience but I believe there's also an issue of regulator performance if you have an OOG situation, it's surely better to have each reg of an independent 1st stage if you can? steve. I'm not sure about performance issue, maybe there's higher possibility of freezing in cold water due to increased flow. However, if you have H valve then it's definitely better to have two 1st stages because that eliminates possibility on unintentional roll-off of valve that doesn't have 1st stage attached to.

August 23rd, 2006, 10:36 AM	#6 (permalink)
Jonathan(Offline) New Member Join Date: Nov 2005 Location: Kent, UK Posts: 215	Quote: (Originally Posted by WhatAKeepah) OK, I just received copy of Doing It Right: The Fundamentals of Better Diving, and on page 81 JJ states that, "...single tank divers who choose to dive in deeper areas or in overhead environments must adhere to equipment redundancy, and use a "Y" or "H" valve to allow two first stages to be affixed to a single tank." [emphasis added]. As my typical dives are in the 30-35m range, I would say that this is appropriate for me. As MonkSeal says, it's generally the case that you use single tank, single first stage to ~30m and if you need additional redundancy then go straight for twin 12ls. Quote: (Originally Posted by WhatAKeepah) I'm actually waiting on an instructor to find two more people to get a class together soon. Worst case scenario, I'll do it in Florida when I take leave in December...I was just planning on doing Adv Nitrox/Decom while I was there instead...oh well... Also keep an eye on here as a space may come up on one of the UK courses Cheers J

August 23rd, 2006, 10:40 AM	#7 (permalink)
MonkSeal(Offline) Old Member Join Date: Feb 2006 Location: Zagreb, Croatia Posts: 474	Quote: (Originally Posted by WhatAKeepah) ...in overhead environments... For me overhead equals doubles and of course 2 1st stages and manifold.

August 23rd, 2006, 01:50 PM	#8 (permalink)
WhatAKeepah(Offline) New Member Join Date: Jul 2006 Location: La Maddalena, Italy Posts: 26	Quote: (Originally Posted by MonkSeal) For me overhead equals doubles and of course 2 1st stages and manifold. No argument here. Thanks all for your input on this. - Alex

August 23rd, 2006, 03:03 PM	#9 (permalink)
Chrisch(Offline) Hogarthian Heretic Join Date: Dec 2005 Location: Brighton Posts: 104	Quote: (Originally Posted by steve_cooper71) ..in the end I opted for an H valve on my single mainly because it makes changing between doubles and singles a lot simpler. ... Me too. Oddly enough in France an instructor is required by law to have a two outlet tank, but there is no requirement for two 1st stages.... Chris

August 23rd, 2006, 03:12 PM	#10 (permalink)
MonkSeal(Offline) Old Member Join Date: Feb 2006 Location: Zagreb, Croatia Posts: 474	Quote: (Originally Posted by Chrisch) Me too. Oddly enough in France an instructor is required by law to have a two outlet tank, but there is no requirement for two 1st stages.... Chris ... which can lead to very dangerous situation: the post without 1st stucked in on position - instant loss of gas.