DIR- GUE Balanced rig with a thick wetsuit - mathematically impossible?
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Eric Sedletzky
Contributor
Sure you can, if you don’t go too deep and have really strong legs. Or ditch the belt if you haven’t been down long enough to worry about it, and don’t care about safety stops.
If you have a total BC failure you won’t have to worry about air expanding in the bladder so you won’t be rocketing to the surface, just a slow gentle ascent. Wetsuits don’t expand that quick.
How many total BC failures have you people heard about that it’s causing this much fuss? You’d think it happens ten times a day the way you guys are carrying on.
You people need to go out and get a life, then after that do a dive with no BC at least once to understand that diving with no BC can be done.
It’s a hell of a learning experience and a crash course on proper weighting.
JoeTPhilly
Contributor
Maybe it is overthinking and I too wonder what can possibly happen to the BC to cause total failure. However, I think the purpose of the example given in class is to get the student thinking about weighting and understanding the balanced rig concept. A lot of students are taking Fundamentals after taking OW or maybe AOW and weren't exposed to the information. I know I wasn't. However, what I did learn from AOW was that I wanted/needed more training and Fundamentals was my choice.
As to the example, it got me asking myself questions about weighting and what it means to dive a balanced rig considering the two extremes; 1: Divers should be able to hold a stop with nearly empty tanks and 2: Divers should be able to surface with a failed wing.
Below are some of the questions and observations I got out of the example. I bet the OP had some of the same observations based on the posting of the thread. If I am wrong let me know.
Is this a balanced rig? Why or why not? No. Although it meets extreme 1, being able to hold a stop with nearly empty tanks, it doesn't meet extreme 2, being able to surface with a failed wing. The diver is 22 pounds negative at 100 feet and the baseline weight that a diver can comfortably swim up to the surface is 10 pounds so the diver is overweight by 12 pounds for extreme 2.
Is this a balanced rig if the diver dropped the weight belt? Why or why not? No. If the diver dropped the 12 pound weight belt it brings them down to negative 10 pounds and they can comfortably surface so now extreme 2 is fulfilled; however, extreme 1 would not. At 10 feet the diver would be underweight by at least 6 pounds and maybe more depending on how much gas was used to ascend.
Is this a balanced rig if the diver had ditch-able weights equal to the weight of the gas in the tank? Why or why not? No. If the diver just ditched the weight of the gas they would be good to go for extreme 1 but would not fulfill extreme 2. The diver would drop 6 of the 12 pounds carried but would now be negative 16 pounds or 6 pounds over the 10 pound weight standard.
I realized that just doing a weight check at the end of a dive with an empty wing and near empty tanks may be insufficient since it doesn't take into consideration the beginning of the dive (extreme 2).
I learned from this thread options alternatives for a diver to surface with an unbalanced rig from old school shopping bags, better finning skills, DSMBs, bigger lung capacity, better fitness etc.
I realized why a drysuit would be preferred over a heavy wetsuit.
I realized that is impossible to balance the rig in the example. However, I think that was the intention so that I or any student would think about weighting in a wholistic manner. To really think about everything so one is properly weighted and not overweighted like many divers coming out of OW and AOW.
Maybe it is overthinking but I feel the example and the observations that come from it has made me a safer diver.
Now can we get back to talking about pee valves?
As to the example, it got me asking myself questions about weighting and what it means to dive a balanced rig considering the two extremes; 1: Divers should be able to hold a stop with nearly empty tanks and 2: Divers should be able to surface with a failed wing.
Below are some of the questions and observations I got out of the example. I bet the OP had some of the same observations based on the posting of the thread. If I am wrong let me know.
Is this a balanced rig? Why or why not? No. Although it meets extreme 1, being able to hold a stop with nearly empty tanks, it doesn't meet extreme 2, being able to surface with a failed wing. The diver is 22 pounds negative at 100 feet and the baseline weight that a diver can comfortably swim up to the surface is 10 pounds so the diver is overweight by 12 pounds for extreme 2.
Is this a balanced rig if the diver dropped the weight belt? Why or why not? No. If the diver dropped the 12 pound weight belt it brings them down to negative 10 pounds and they can comfortably surface so now extreme 2 is fulfilled; however, extreme 1 would not. At 10 feet the diver would be underweight by at least 6 pounds and maybe more depending on how much gas was used to ascend.
Is this a balanced rig if the diver had ditch-able weights equal to the weight of the gas in the tank? Why or why not? No. If the diver just ditched the weight of the gas they would be good to go for extreme 1 but would not fulfill extreme 2. The diver would drop 6 of the 12 pounds carried but would now be negative 16 pounds or 6 pounds over the 10 pound weight standard.
I realized that just doing a weight check at the end of a dive with an empty wing and near empty tanks may be insufficient since it doesn't take into consideration the beginning of the dive (extreme 2).
I learned from this thread options alternatives for a diver to surface with an unbalanced rig from old school shopping bags, better finning skills, DSMBs, bigger lung capacity, better fitness etc.
I realized why a drysuit would be preferred over a heavy wetsuit.
I realized that is impossible to balance the rig in the example. However, I think that was the intention so that I or any student would think about weighting in a wholistic manner. To really think about everything so one is properly weighted and not overweighted like many divers coming out of OW and AOW.
Maybe it is overthinking but I feel the example and the observations that come from it has made me a safer diver.
Now can we get back to talking about pee valves?
Attachments
PfcAJ
Contributor
The elbow separating from the bladder results in a total failure.
Eric Sedletzky
Contributor
And it doesn’t have to be all your weight either, it could be partial weight on a belt like 5 or 10 lbs.
There is another consideration people are missing.
During a deep dive in a wetsuit the material cools which lessens the bubble size in the neoprene making it less buoyant combined with the crushing effect from pressure. So a single tank diver starts a dive with a warm inflated wetsuit and a full tank with a gas weight of say 6 lbs.
As the air get depleted at depth the tank gets lighter and as the bottom time goes on the suit will continue to get heavier. So essentially what’s happening is the tank and the suit are just trading buoyancy. This is why I say you must check your weighting AT THE END OF A FULL LENGTH DIVE TO DEPTH with a near empty tank at the final stop depth of your choice. You should be able to hold a stop with an empty bc at your stop depth and maintain it with breathing alone.
I don’t know where the term “balanced rig” came from to mean proper weighting, because that’s really all it is. It’s the sum total of ballast on the diver however broken up to be perfectly weighted. It has nothing to do with just the rig because that’s just one component of the sum total. Balanced rig used to mean you were evenly weighted and your rig was evenly weighted (non integrated) so if you removed your rig at depth both you and your rig would be neutral, AKA “balanced rig”. Somewhere along the line this term was taken because it sounds tech and cool but it’s actually a misnomer.
This is not the real life.
You are not considering your lungs in these calculations...
When I started diving there was no BCD.
We were using steel twin tanks (10+10 liters) with reserve, no SPG, two complete independent regs on two separated valves, a 6.5mm Scubapro wet suit made of Rubatex neoprene (no nylon lining outside), Beuachat Jetfin long fins (much more powerful than the subsequent Scubapro bad copy).
The max depth was 50m with a couple of mandatory deco stops.
Typycally 5-6 kg of lead weights were enough. My wife was using no weight at all!
Surely we were negative down at 50m with the tanks full.
But why to ascend?
We did wait to get into reserve before ascending...
At that time the tanks did contain just 50 bar, not 200, so we had 4kg more buoyancy and kicking properly (double effect flutter kick, without flexing significantly your knees, of course, not the crap frog kicking) ascending was not a problem.
If one had to ascend earlier, with tank almost full and not having any deco obligation yet, ditching some weight was considered perfectly acceptable. And at that point there was no need to be neutral at 3m for a deco stop, the ascent was directly to surface.
Of course the BCD made diving at such depth much more easy and safe.
But, as we were able of doing it also without any BCD, the sudden loss of the air in the bladder had never been a problem.
And almost everyone was using the Bucher's invention of storing a shopper plastic bag, usually inside the left arm sleeve of the suit, just in case one needed more buoyancy.
Of course this was done entirely outside the DIR approach, simply because such a diving method had not been yet invented.
I also invite you to try diving without any BCD, possibly with a super-streamlined setup. I am sure you will enjoy it, it gives a sense of freedom that you loose when you are equipped with a standard DIR compliant rig...
And do not forget the plastic bag!
You don't keep diving after your wing fails... and if you can swim up 10lb you can swim down 6lbs (roughly the volume of a full lung)
When the first BCDs were introduced (or self built, as my one, made from a Vespa tire bladder and named "boiata compensator") failures were common.
It was not considered a reason for ending the dive. The BCD was usually left empty, it was considered just an additional safety device.
It could be manually (orally) inflated, or burst full by firing a CO2 cartridge. There was no "power inflator", allowing to carefully adjust the buoyancy...
johndiver999
Contributor
The spring can corrode and fail, the OPV cover can become loose and unscrewed and fall off, a zip tie on the corrugated hose can fail, The OPV valve base can crumble from aging and with no prior leakage or warning.
I've had a few failures myself, seem a few others and have probably eliminated many impending failures simply by checking the tightness of OPV valves.
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