Personally..I'd pull water into my mouth, swish it around real hard then blow the hydrogen into the wing and the O2 out into the water. You must be careful not to swallow any of the pure O2 at depth.
Let's talk about balanced rigs
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JeffG
Contributor
What?? Didn't you O2 clean your bcd?
Jeez, hate it when having to work cuts into my posting on forums...
Jeff, I'm not being sarcastic, and so far I'm not antagonized. And actually I think you made my point here:
Back to the 230' wreck, or the Agamemnon Channel - either way if I run into bouyancy issues on the wreck my Plan A is to thumb the dive and head up escorted by the other divers I'm teamed up with. In the event of a catastrophic team breakdown, my Plan B involves scootering over to the anchor line and motoring up, stopping as needed (as you say, if your issues occur early enough in the dive you don't have any significant deco obligation).
If I understand your argument correctly, you're saying that when diving with a balanced rig your Plan A (or B) would be to un-buckle your waiststrap and ditch the can light; (assuming no substantial deco obligation) unclip your deco bottles and jettison them; (if you had a camera or scooter you may also ditch that,) and swim your rig up the 230' or so to the surface. Or be able to swim your rig up the 230' to the surface.
I'm having problems seeing that as a more optimal solution. Mostly because I suspect that my CO2 levels would likely rise, because I was exerting myself, such that somewhere coming up between 200' and 100' there is a possibility I may black out.
FWIW, my tanks were filled with a helium mix, one 40 held 50/50, the other 100% O2. As I noted, the 6 cuft tank held 'airgon'. I was wearing a thin polypro layer with a thicker fleece undergarment. I'm aware that scooters are neutrally bouyant, but they have mass - resistance that adds drag, increasing the amount of effort needed to push them through the water.
Had I ditched all my sling tanks and scooter its possible that I may have been able to swim the backgas up, but there are still physiological issues with CO2 loading at work.
I'm not against being able to swim to the surface if you have issues, but I disagree with the dogma that suggests that a 'balanced rig' is universally an optimal solution.
Beyond a certain level of diving, I don't find that a compelling argument. Taking into consideration issues of CO2 loading; and the costs of jettisoning tanks, gas, and scooters (both in terms of money and in terms of resources you could use on the way up); my argument is that there's a better way to plan deep dive problem-solving than ditching your can light and sling tanks and swimming up. But thats just me. If it works for you, great.
Where we agree is here:
If you decide you want to do the dive, then you also need to figure out how you're going to respond safely to issues that may occur during those dives where "some rigs can't be balanced".
Jeff, I'm not being sarcastic, and so far I'm not antagonized. And actually I think you made my point here:
Back to the 230' wreck, or the Agamemnon Channel - either way if I run into bouyancy issues on the wreck my Plan A is to thumb the dive and head up escorted by the other divers I'm teamed up with. In the event of a catastrophic team breakdown, my Plan B involves scootering over to the anchor line and motoring up, stopping as needed (as you say, if your issues occur early enough in the dive you don't have any significant deco obligation).
If I understand your argument correctly, you're saying that when diving with a balanced rig your Plan A (or B) would be to un-buckle your waiststrap and ditch the can light; (assuming no substantial deco obligation) unclip your deco bottles and jettison them; (if you had a camera or scooter you may also ditch that,) and swim your rig up the 230' or so to the surface. Or be able to swim your rig up the 230' to the surface.
I'm having problems seeing that as a more optimal solution. Mostly because I suspect that my CO2 levels would likely rise, because I was exerting myself, such that somewhere coming up between 200' and 100' there is a possibility I may black out.
I'm assuming that what you mean by this statement is that your 'rig in salt water filled with helium mix was very balanced' without any stage bottles or deco bottles, right?
FWIW, my tanks were filled with a helium mix, one 40 held 50/50, the other 100% O2. As I noted, the 6 cuft tank held 'airgon'. I was wearing a thin polypro layer with a thicker fleece undergarment. I'm aware that scooters are neutrally bouyant, but they have mass - resistance that adds drag, increasing the amount of effort needed to push them through the water.
Had I ditched all my sling tanks and scooter its possible that I may have been able to swim the backgas up, but there are still physiological issues with CO2 loading at work.
I'm not against being able to swim to the surface if you have issues, but I disagree with the dogma that suggests that a 'balanced rig' is universally an optimal solution.
Beyond a certain level of diving, I don't find that a compelling argument. Taking into consideration issues of CO2 loading; and the costs of jettisoning tanks, gas, and scooters (both in terms of money and in terms of resources you could use on the way up); my argument is that there's a better way to plan deep dive problem-solving than ditching your can light and sling tanks and swimming up. But thats just me. If it works for you, great.
Where we agree is here:
If you decide you want to do the dive, then you also need to figure out how you're going to respond safely to issues that may occur during those dives where "some rigs can't be balanced".
JeffG
Contributor
That's the definition. But adding the other stuff is really insignificant. You are talking about an extra 3-4 lbs. Physics is a stubborn thing.
Has nothing to do with the current conversation.
on the internet I guess. LOL
Why do you keep bringing up the scooter?????? ITS NEUTRAL!!!!!!
No, you said its a myth.
Just because you are unable to dive a balanced rig doesn't make it a myth.
I don't think you understand it.
LOL
It fascinates me how this thread has morphed from a question that arose from a recreational, single tank dive, into what one does with scooters and multiple deco bottles.
In answer to the original question -- steel tanks and thick wetsuits can make a pernicious combination. This was one of the examples we worked through in Fundies, that made me look at the instructor and think, "Wow, these guys have really thought things through." What works at the surface is a whole different animal at 100 feet, where a thick wetsuit can lose a large percentage of its original buoyancy. Then you are at depth with a large, negative tank, and you're 20 lbs more negative than you were at the surface, due to neoprene compression. At that point, you either need some kind of redundant buoyancy (and a 6 lb SMB may not be enough) or you need weight you can jettison (recognizing that discarding it may make it quite difficult to control the later portions of your ascent).
This is why the DIR recommendation is not to dive deep in cold water in a wetsuit. It's hard to make it work.
In answer to the original question -- steel tanks and thick wetsuits can make a pernicious combination. This was one of the examples we worked through in Fundies, that made me look at the instructor and think, "Wow, these guys have really thought things through." What works at the surface is a whole different animal at 100 feet, where a thick wetsuit can lose a large percentage of its original buoyancy. Then you are at depth with a large, negative tank, and you're 20 lbs more negative than you were at the surface, due to neoprene compression. At that point, you either need some kind of redundant buoyancy (and a 6 lb SMB may not be enough) or you need weight you can jettison (recognizing that discarding it may make it quite difficult to control the later portions of your ascent).
This is why the DIR recommendation is not to dive deep in cold water in a wetsuit. It's hard to make it work.
Welcome to ScubaBoard!
The spinoff may have come from a single tank recreatonald dive origin, but the question posed by the OP in this thread was one of balanced rigs. That doesn't imply purely recreational responses.
I suppose I'm partially to blame for the spinoff since I was one of the first posters to respond and mentioned both recreational and tech set ups. One would hope that by the time people have moved into heavy steel doubles, deco/stage bottles, scooters, etc. that their training has covered some of these aspects already and given rise to the "what if" scenarios. As I progressed through my tech training, I recall several classes where showing proficiency in shooting a bag and handling multiple sources of bouyancy was a requirement.
Hopefully, some of the answers given relating to tech will give recreational folk pause before deciding to ditch AL80's and move to heavy steel singles, etc. It may just open their eyes to things they've never considered before.
Gentlemen,
In the light of information exchange and trying to clarify the situation a bit, I offer the following for your consideration. Jeff and Doc, if you disagree with some of the numbers in my math or any of the starting assumptions, please correct me in this particular area. I realize that this is far from a recreational "balanced rig" question but as Cave Diver pointed out, sometimes the issues on the sharp end of the stick have relevance to issues closer to the middle of the stick.
In using the example of a 220' dive in salt water I am starting with a fully kitted out tech diver with double steel 130's, an AL 80 bottom stage, one Al 80 of 50% (or Al 40 depending on run time) and one Al 40 of 100%. This diver has a scooter and no camera. This diver is diving 15/55 trimix and wearing a 400 gm thinsulate undergarment and a tri lam drysuit. He is also carrying a typical 21 watt HID light. Since our gang regularly dives in this kind of environment I am using my weighting as a starting point.
When diving double 130's with this exposure protection, in order to remain neutral with 500 or so psi in my doubles at the end of a dive, I use a 5.5 kg backplate and no additional weighting other than my can light. I am about 5' 11 and 215 pds and play rugby. I am fairly dense (ask my wife) and sink in a swimming pool. I am not a "floaty" person. Hence, with just this gear and no additional equipment, at the start of every "recreational" doubles dive, I am about 15 lbs negative which is simply the weight of the gas in my filled 130's.
Now back to the tech dive outlined above. My bottom stage adds about 4lbs (trimix) to the equation at the beginning of the dive. My 50% bottle, about 5 lbs, my al 40, maybe 2 lbs. Because my backgas is 55% helium, which is about 1/5 the weight of air, 55% of my gas weight in my back gas is 20% as heavy......For making the math easier, lets say that half of my back gas weight (which was 15 lbs) is now 20% as heavy, which means 7. 5 lbs is now about 2 lbs. Thus, my back gas weight for this mix is now 9.5 lbs instead of 15 lbs. (7.5 lbs + 2 lbs).
Thus, the weight of my stages, deco and gas is 4 lbs + 5 lbs + 2lbs + 9.5 lbs, which equals 20.5 lbs.
But remember that my bottom stage and my 50% bottle are going to be closer to empty when I get to my 02 stop so I need to add weight to my starting weight in order to remain neutral. In this case, my bottom stage is now going to be about 2 lbs buoyant but my 50% bottle will probably still be a bit negative as it is doubtful I would use all that 50% gas for this dive. Thus, at the very least I would want to add 2 lbs to my weighting to be able to hold my 02 stops. In reality, since there is nothing worse than fighting to hold that stop for 30-40 minutes, we add a couple more pounds (small v-weight) to help this.
Thus, at the beginning of this dive, I have my gas weight of nearly 22 lbs, plus 5 pounds of lead to assist in holding my 02 stop. This comes very close to Doc's 30 pound overweight statement at the beginning of his dive, and I personally do not believe I could swim 27lbs up from any kind of depth, regardless of C02 loading. I wouldn't even want to try it in 30' of water actually.
So what the hell can we do? The first thing we can do is plan to get rid of the bottom stage at the end of the dive, thus getting rid of 2 lbs of the static weighting we needed to hold the 02 stop. We could send it up the line or meet midwater support and get rid of it. Getting rid of the 50% bottle is an option but you may not have to as you might not have used all you 50% gas on this dive and the bottle could be still slightly negative or even neutral. You may have started the dive with an Al 40 of 50% depending on run time so you might still want to unload that bottle as well as it would be slightly buoyant by that time. Regardless, unloading these two bottles would only let you get rid of a maximum of 5 lbs of lead at the beginning of your dive and my personal thoughts are that I am not going to get rid of my 50% bottle if it still has gas in it. But that could just be me. Moreover, I think it is a very bad idea to start the dive knowing that you couldn't hold your 02 stop with the kind of gas loading we are talking about. Missing your surface support is entirely possible in blue water with drifting deco and unknown currents so I personally would not do this, nor would I make my weighting plan contingent on ditching my bottom stage because that would mean that I have to get rid of the thing, regardless of circumstances. I can always unload it if I have to but I might prefer not to. They aren't really disposable dive equipment..........
So anyway we slice it, you are going to be a minimum of 22 to 27 lbs negative at the beginning of the dive and I don't think I want to try to swim that up.
Notice I didn't say anything about the scooter. The thing is neutral and while it might have some drag when swimming, if the bloody thing is working I would use it instead of swimming, but then I am inherently lazy.
So what can you do? The problem is clearly one of balancing your weighting at the end of your dive where you require enough to stay neutral and the weight of the gas and equipment at the beginning of the dive you required to do that dive. In my view, equipment can be replaced while my life can not. I am funny that way.......... If I had a disastrous wing failure at the beginning of the dive when I was overweighted, my first option is my buddies. I could unload some of my bottles to them and also use my drysuit for buoyancy. Not fun and you better stay on top of the power curve on this one with practise. One poster asked what to do if you also had buddy seperation . At this point, I am unloading my bottom stage (-4 lbs), unloading my 50% bottle (-5 lbs), unloading my canister light (-2 lbs) and probably even unloading my argon bottle (-1-2 lbs), and maybe even my 02 bottle. The 02 bottle would be the last to go for me as it only adds 1-2 pounds the equation. So in this almost worst case scenario, I have unloaded about 12 lbs of that at least 22 lbs or 27 lbs. This means I have to swim up 10 pounds or 15 lbs. Again not a lot of fun no question. But I still have my drysuit right? As I ascend, it is going to add buoyancy. So what if my drysuit is also screwed. Remember that scooter I had? Sure glad I didn't get rid of that thing at this point. I also have at least a 6lb closed circuit SMB in my pocket. Might be nice if my scooter didn't work, my drysuit was screwed, my wing was holed, my buddies were gone.........etc........
So when the rubber hits the road what does this exercise demonstrate? I propose that there is no way in hell that a fully kitted out tech diver can ever start a dive like the above in a neutral state. Moreover, he is going to be at least 22-27 pounds negative at the start of his/her dive.
Further, you have various tools at your disposal to help you deal with failures, but I believe we have to be realistic about the number of failures we plan for: buddy seperation? I am outta here. Wing failure? I am on my way home with or without some of my gear. Drysuit failure? Same thing. All these things happening at the same time? The sport has inherent risks. Period. But in my view, when the perfect storm comes along, it comes along. It is a question of how likely this could come along. I plan for one major failure and shut things down. Three or four in one dive? Somebody really doesn't like me and I am probably screwed. But I don't get out of bed each morning worrying about getting in a car crash and then getting hit by a passing car as I extricate myself from my broken vehicle, while I am also getting struck by lightning.
You also have the chance to just not do this type of dive. This is just a sport and nothing in the ocean is worth dying for so maybe the risks in this diveplan risks are unacceptable to many people. I think it also points out several very serious considerations: Doing this type of diving with a team that is not switched on is a very bad idea. A well practiced team is less likely to get seperated, can help with moving gear around, can take extra gear and manage a bad situation in a far less "dramatic" fashion than a bunch of dudes who are on the "same day-same ocean" program. Moreover, this diving requires some significant training. Maintaining your poise and keeping your wits about you when the **** hits the fan requires skill, training, and constant practise. Simply thinking through this problem while at depth and facing possible catastrophic consequences will use up a lot, if not most, of your available bandwidth. You don't have a lot of left over brain cells to deal with buoyancy issues, etc. This stuff has to be ingrained in your subconcious.
So I open to floor for comments. Jeff, I get the impression that you have some different views here and I welcome your input. Please take apart my scenario and beginning assumptions and show me where my thought process is flawed. I am in a constant state of learning and I am looking forward to a different analysis of this scenario. Same for you Doc, if you disagree with anything I wrote, please show me where I was wrong.
Learning never stops and even my grandma told me that several halfwits can usually equal more than a full wit.......I think she was including me in the halfwit category........
In the light of information exchange and trying to clarify the situation a bit, I offer the following for your consideration. Jeff and Doc, if you disagree with some of the numbers in my math or any of the starting assumptions, please correct me in this particular area. I realize that this is far from a recreational "balanced rig" question but as Cave Diver pointed out, sometimes the issues on the sharp end of the stick have relevance to issues closer to the middle of the stick.
In using the example of a 220' dive in salt water I am starting with a fully kitted out tech diver with double steel 130's, an AL 80 bottom stage, one Al 80 of 50% (or Al 40 depending on run time) and one Al 40 of 100%. This diver has a scooter and no camera. This diver is diving 15/55 trimix and wearing a 400 gm thinsulate undergarment and a tri lam drysuit. He is also carrying a typical 21 watt HID light. Since our gang regularly dives in this kind of environment I am using my weighting as a starting point.
When diving double 130's with this exposure protection, in order to remain neutral with 500 or so psi in my doubles at the end of a dive, I use a 5.5 kg backplate and no additional weighting other than my can light. I am about 5' 11 and 215 pds and play rugby. I am fairly dense (ask my wife) and sink in a swimming pool. I am not a "floaty" person. Hence, with just this gear and no additional equipment, at the start of every "recreational" doubles dive, I am about 15 lbs negative which is simply the weight of the gas in my filled 130's.
Now back to the tech dive outlined above. My bottom stage adds about 4lbs (trimix) to the equation at the beginning of the dive. My 50% bottle, about 5 lbs, my al 40, maybe 2 lbs. Because my backgas is 55% helium, which is about 1/5 the weight of air, 55% of my gas weight in my back gas is 20% as heavy......For making the math easier, lets say that half of my back gas weight (which was 15 lbs) is now 20% as heavy, which means 7. 5 lbs is now about 2 lbs. Thus, my back gas weight for this mix is now 9.5 lbs instead of 15 lbs. (7.5 lbs + 2 lbs).
Thus, the weight of my stages, deco and gas is 4 lbs + 5 lbs + 2lbs + 9.5 lbs, which equals 20.5 lbs.
But remember that my bottom stage and my 50% bottle are going to be closer to empty when I get to my 02 stop so I need to add weight to my starting weight in order to remain neutral. In this case, my bottom stage is now going to be about 2 lbs buoyant but my 50% bottle will probably still be a bit negative as it is doubtful I would use all that 50% gas for this dive. Thus, at the very least I would want to add 2 lbs to my weighting to be able to hold my 02 stops. In reality, since there is nothing worse than fighting to hold that stop for 30-40 minutes, we add a couple more pounds (small v-weight) to help this.
Thus, at the beginning of this dive, I have my gas weight of nearly 22 lbs, plus 5 pounds of lead to assist in holding my 02 stop. This comes very close to Doc's 30 pound overweight statement at the beginning of his dive, and I personally do not believe I could swim 27lbs up from any kind of depth, regardless of C02 loading. I wouldn't even want to try it in 30' of water actually.
So what the hell can we do? The first thing we can do is plan to get rid of the bottom stage at the end of the dive, thus getting rid of 2 lbs of the static weighting we needed to hold the 02 stop. We could send it up the line or meet midwater support and get rid of it. Getting rid of the 50% bottle is an option but you may not have to as you might not have used all you 50% gas on this dive and the bottle could be still slightly negative or even neutral. You may have started the dive with an Al 40 of 50% depending on run time so you might still want to unload that bottle as well as it would be slightly buoyant by that time. Regardless, unloading these two bottles would only let you get rid of a maximum of 5 lbs of lead at the beginning of your dive and my personal thoughts are that I am not going to get rid of my 50% bottle if it still has gas in it. But that could just be me. Moreover, I think it is a very bad idea to start the dive knowing that you couldn't hold your 02 stop with the kind of gas loading we are talking about. Missing your surface support is entirely possible in blue water with drifting deco and unknown currents so I personally would not do this, nor would I make my weighting plan contingent on ditching my bottom stage because that would mean that I have to get rid of the thing, regardless of circumstances. I can always unload it if I have to but I might prefer not to. They aren't really disposable dive equipment..........
So anyway we slice it, you are going to be a minimum of 22 to 27 lbs negative at the beginning of the dive and I don't think I want to try to swim that up.
Notice I didn't say anything about the scooter. The thing is neutral and while it might have some drag when swimming, if the bloody thing is working I would use it instead of swimming, but then I am inherently lazy
.So what can you do? The problem is clearly one of balancing your weighting at the end of your dive where you require enough to stay neutral and the weight of the gas and equipment at the beginning of the dive you required to do that dive. In my view, equipment can be replaced while my life can not. I am funny that way.......... If I had a disastrous wing failure at the beginning of the dive when I was overweighted, my first option is my buddies. I could unload some of my bottles to them and also use my drysuit for buoyancy. Not fun and you better stay on top of the power curve on this one with practise. One poster asked what to do if you also had buddy seperation . At this point, I am unloading my bottom stage (-4 lbs), unloading my 50% bottle (-5 lbs), unloading my canister light (-2 lbs) and probably even unloading my argon bottle (-1-2 lbs), and maybe even my 02 bottle. The 02 bottle would be the last to go for me as it only adds 1-2 pounds the equation. So in this almost worst case scenario, I have unloaded about 12 lbs of that at least 22 lbs or 27 lbs. This means I have to swim up 10 pounds or 15 lbs. Again not a lot of fun no question. But I still have my drysuit right? As I ascend, it is going to add buoyancy. So what if my drysuit is also screwed. Remember that scooter I had? Sure glad I didn't get rid of that thing at this point. I also have at least a 6lb closed circuit SMB in my pocket. Might be nice if my scooter didn't work, my drysuit was screwed, my wing was holed, my buddies were gone.........etc........
So when the rubber hits the road what does this exercise demonstrate? I propose that there is no way in hell that a fully kitted out tech diver can ever start a dive like the above in a neutral state. Moreover, he is going to be at least 22-27 pounds negative at the start of his/her dive.
Further, you have various tools at your disposal to help you deal with failures, but I believe we have to be realistic about the number of failures we plan for: buddy seperation? I am outta here. Wing failure? I am on my way home with or without some of my gear. Drysuit failure? Same thing. All these things happening at the same time? The sport has inherent risks. Period. But in my view, when the perfect storm comes along, it comes along. It is a question of how likely this could come along. I plan for one major failure and shut things down. Three or four in one dive? Somebody really doesn't like me and I am probably screwed. But I don't get out of bed each morning worrying about getting in a car crash and then getting hit by a passing car as I extricate myself from my broken vehicle, while I am also getting struck by lightning.
You also have the chance to just not do this type of dive. This is just a sport and nothing in the ocean is worth dying for so maybe the risks in this diveplan risks are unacceptable to many people. I think it also points out several very serious considerations: Doing this type of diving with a team that is not switched on is a very bad idea. A well practiced team is less likely to get seperated, can help with moving gear around, can take extra gear and manage a bad situation in a far less "dramatic" fashion than a bunch of dudes who are on the "same day-same ocean" program. Moreover, this diving requires some significant training. Maintaining your poise and keeping your wits about you when the **** hits the fan requires skill, training, and constant practise. Simply thinking through this problem while at depth and facing possible catastrophic consequences will use up a lot, if not most, of your available bandwidth. You don't have a lot of left over brain cells to deal with buoyancy issues, etc. This stuff has to be ingrained in your subconcious.
So I open to floor for comments. Jeff, I get the impression that you have some different views here and I welcome your input. Please take apart my scenario and beginning assumptions and show me where my thought process is flawed. I am in a constant state of learning and I am looking forward to a different analysis of this scenario. Same for you Doc, if you disagree with anything I wrote, please show me where I was wrong.
Learning never stops and even my grandma told me that several halfwits can usually equal more than a full wit.......I think she was including me in the halfwit category........
JeffG
Contributor
My setup is close to yours.
Here are the differences.
I did the dive with an al40 of 50%
My Backplate is an Al plate with a tail weight and a 6lb belt.
So, I am not as heavy due to the minor change in the 50% bottle and I have 6lbs of low cost ditchable weight.
So I would drop my belt as a first resort. If I couldn't cheat my drysuit into carrying the load (which would be approx 16-20lbs using your numbers) I would start handing my bottles to my buddy...until I could (carry the load).
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