I'd like to delve a bit into gas management since I rarely hear anyone doing any at the sites I visit (except for cavers). So to that end:
When planning your dives, how much or your buddy's gas belongs to you?
How much of your buddies gas is yours?
Started by
PerroneFord
, Aug 16 2006 10:06 AM
77 replies to this topic
#1
PerroneFord
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Posted 16 August 2006 - 10:06 AM
#2
ScubaDadMiami
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Posted 16 August 2006 - 10:17 AM
On closed circuit, we use another scheme for these situations. We carry 1.5 times the required gas to get to the surface or other staged tanks between the total team members. So, if there are three of us, and we are at the farthest point in our dive (such as maximum penetration into the wreck), and it would require 80 cubic feet to get back to the surface, each of the divers on the team will carry a 40 cubic foot tank for bailout, making a total of 120 cubic feet of available bail out gas between all team members.
The prodecure is to breathe down the bail out tank until half of it is used. Then, switch tanks with someone else until all bail out tanks are down to half. Then, breathe down half of what is left, and continue the cycle.
If we are in a mixed group, where someone is on open circuit, that person observes the rule of thirds but the remainder of us carry the balance to make the 1.5 times required gas. We usually won't do bigger, longer dives with open circuit divers on the team since they will have to drag stages and klunky tanks all over the place, and even then, they will have a much reduced bottom time compared to the CCR divers. It's still possible, but I would have to know these divers well before I would consider such a move.
Much of the time, I treat my situation as if I am a solo diver even when I am not. In those instances, I carry enough gas to make it back to the suface with some extra gas left for contingencies.
The prodecure is to breathe down the bail out tank until half of it is used. Then, switch tanks with someone else until all bail out tanks are down to half. Then, breathe down half of what is left, and continue the cycle.
If we are in a mixed group, where someone is on open circuit, that person observes the rule of thirds but the remainder of us carry the balance to make the 1.5 times required gas. We usually won't do bigger, longer dives with open circuit divers on the team since they will have to drag stages and klunky tanks all over the place, and even then, they will have a much reduced bottom time compared to the CCR divers. It's still possible, but I would have to know these divers well before I would consider such a move.
Much of the time, I treat my situation as if I am a solo diver even when I am not. In those instances, I carry enough gas to make it back to the suface with some extra gas left for contingencies.
"The most important thing is not to stop questioning." Albert Einstein
"For the diligent diver, closed circuit rebreathers are actually safer than open circuit scuba." Tom Mount
"For the diligent diver, closed circuit rebreathers are actually safer than open circuit scuba." Tom Mount
#3
Walter
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Posted 16 August 2006 - 10:34 AM
I never expect to get any gas from my buddy.
No single raindrop believes it is responsible for the flood.
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#4
PerroneFord
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Posted 16 August 2006 - 10:39 AM
I never expect to get any gas from my buddy.
With that winning smile and your charm??? Maybe cut back on the onions...
#5
Diverbrian
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Posted 16 August 2006 - 10:49 AM
The gas that my buddy requires to do deco should be theirs. But, typically you don't see me discussing with my recreational buddies because I am using high capacity doubles for most of my diving and have been called a Sunoco station often enough. In no deco diving, I just need to worry about getting both of us up and 500 psi of double E8-130's is a whole heck of a lot of gas when that buddy is diving smaller tanks.
Otherwise, I multiply my gas needs by 1.5 and make sure to that amount with me. I don't tend to count on getting extra from my buddy, but they had better be able to get it from me if at all possible.
Another factor on this is gas mixes. I tend to dive helium mixes which will throw my dive buddies planned ascent profile off if they need to get gas from me. So, it is definitely an emergency in many cases if my buddy requires my gas. There is one buddy that vent the helium for to better match mixes and that person knows who they are.
Otherwise, I multiply my gas needs by 1.5 and make sure to that amount with me. I don't tend to count on getting extra from my buddy, but they had better be able to get it from me if at all possible.
Another factor on this is gas mixes. I tend to dive helium mixes which will throw my dive buddies planned ascent profile off if they need to get gas from me. So, it is definitely an emergency in many cases if my buddy requires my gas. There is one buddy that vent the helium for to better match mixes and that person knows who they are.
A person should be judged in this life not by the mistakes that they make nor by the number of them. Rather they are to be judged by their recovery from them.
#6
Latitude Adjustment
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Posted 16 August 2006 - 11:25 AM
I always have extra air and have never planned around will my buddy have enough for me mainly because most have higher SCR's than me and bottom times are based on their air use and NDL times.
On the last trip I was on I saw a lot of air sharing and only once was it a drill between a DM and student. The rest of the times it seemed to be poor planing for the safety stops where one of the buddies didn't have enough air for the stops and hadn't signaled that they needed to assend sooner.
On the last trip I was on I saw a lot of air sharing and only once was it a drill between a DM and student. The rest of the times it seemed to be poor planing for the safety stops where one of the buddies didn't have enough air for the stops and hadn't signaled that they needed to assend sooner.
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#7
mantarraya
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Posted 16 August 2006 - 11:42 AM
I trust that was the same trip where I saw lots of air sharing. That was definitely the most air-sharing I ever saw at a time - as many as 3 buddy teams sharing air and on more than one dive. I don't have any problem with it - the air supplying buddy seemed to have plenty left and was comfortable with the process. It almost seemed they were just trying to keep the group together as much as possible on the drift dives to make it easier for the boat to pick up, but then some people were going up early, too. Perhaps part of the issue was that we had one boat, but two groups that had gone in at slightly different times, so keeping any one group together was a good thing for the boat guys tracking the groups.On the last trip I was on I saw a lot of air sharing and only once was it a drill between a DM and student. The rest of the times it seemed to be poor planing for the safety stops where one of the buddies didn't have enough air for the stops and hadn't signaled that they needed to assend sooner.
Back after a long absence - whew, too busy at work!
#8
drbill
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Posted 16 August 2006 - 12:06 PM
As a solo diver who goes deep, I have to continually utilize gas management. I dive with a 120 cu ft primary tank usually only filled to an effective 100 cu ft on the dive boat. Although I always carry a 19 cu ft pony, it is only for emergency use. On really deep dives (> 150 ft) I often carry a 30 cu ft.
Many of my dives the past few months have been deep (150-200 ft) using this set up. I am pretty comfortable judging my air consumption, and will plan for deco stops that are preferably 3-10X the required length. One day last week I did three dives in the 170-180 ft range and never came close to needing the pony.
I used to practice gas management by setting goals to achieve. For example, using my 120 filled at 3,500si I would set a goal to do two dives to a maximum depth of 80 feet for 50 min each. I would then adjust my depth, breathing rate, etc., to meet that goal (or any other pattern I might choose) returning with 500 psi in the tank. This made the dives an interesting challenge, especially in the days before I took up video.
Many of my dives the past few months have been deep (150-200 ft) using this set up. I am pretty comfortable judging my air consumption, and will plan for deco stops that are preferably 3-10X the required length. One day last week I did three dives in the 170-180 ft range and never came close to needing the pony.
I used to practice gas management by setting goals to achieve. For example, using my 120 filled at 3,500si I would set a goal to do two dives to a maximum depth of 80 feet for 50 min each. I would then adjust my depth, breathing rate, etc., to meet that goal (or any other pattern I might choose) returning with 500 psi in the tank. This made the dives an interesting challenge, especially in the days before I took up video.
#9
Walter
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Posted 16 August 2006 - 12:55 PM
I never expect to get any gas from my buddy.
With that winning smile and your charm??? Maybe cut back on the onions...
I don't think that's the issue. OOA divers never refuse to take my gas, but I've never needed any from another diver - yet. I plan my dives to not need gas from anyone else.
No single raindrop believes it is responsible for the flood.
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#10
hnladue
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Posted 16 August 2006 - 12:59 PM
My buddy has gas???? Then I'm staying FAR AWAY from him!!! PPEEEEE YYEEEEWWWW!!!
Did he eat beans or something before hand to get that gas.. OMG I'm gonna die!!!
Also wouldn't that cause bouyancy issues??
I'm staying far away when he opens that dry suit too..
No wonder there's no fish around here anymore.
Did he eat beans or something before hand to get that gas.. OMG I'm gonna die!!!
Also wouldn't that cause bouyancy issues??
I'm staying far away when he opens that dry suit too..
No wonder there's no fish around here anymore.
Sempar Partus!!
#11
mantarraya
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Posted 16 August 2006 - 01:22 PM
I guess a bottle of Beano needs to be in everyone's SAVE-A-DIVE kit...just don't try to carry it onboard the airplane on the trip to the dive site!My buddy has gas???? Then I'm staying FAR AWAY from him!!! PPEEEEE YYEEEEWWWW!!!
Did he eat beans or something before hand to get that gas.. OMG I'm gonna die!!!
Back after a long absence - whew, too busy at work!
#12
drbill
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Posted 16 August 2006 - 03:41 PM
OOA divers never refuse to take my gas, but I've never needed any from another diver - yet. I plan my dives to not need gas from anyone else.
Walter... I think of the one time I really needed my pony bottle, or a buddy, when my debris tube clogged and nothing was flowing out of my primary tank. Of course that was only the second time in 45 years I needed a gas source, but it could have been the last one.
#13
Walter
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Posted 16 August 2006 - 04:30 PM
If I remember correctly, that was not long before I dived with you.
No single raindrop believes it is responsible for the flood.
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#14
drbill
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Posted 16 August 2006 - 06:01 PM
If I remember correctly, that was not long before I dived with you.
I believe that is correctimundo. That pony bottle never strays far from my HP120 since the next time I need it might otherwise be the next time I don't take it.
#15
Basslet
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Posted 16 August 2006 - 07:24 PM
I never had to share air either, but if my buddy needs it he/she is welcome to it in an emergency. But if my buddy was constantly running out of air and needed to share all the time, I would find a new buddy. That kind of diving is not my style
Edited by Fairybasslet, 16 August 2006 - 07:28 PM.
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