Balanced rig limits, no bcd?

[northernone]

Balanced rig: Neutral buoyancy limits with no bcd and related safety considerations. Curious what comfort limits others have who regularly dive without a bcd have and what gear configurations work well.

Sharing my observations from a test dive, not suggesting it should be emulated.

Short version: Balenced rig, Two al80s, 2/3mm wetsuit using only lung volume for buoyancy compensation. Comfortable at 65ft. Deco stop at 10' with 500psi also comfortable. Able to hold motionless neutral without uncomfortable breathing patterns or finning.

Longer version:
Remembering the streamlining and comfort of diving without a bcd combined with my newer found love for maintaining the ability to hang motionless without constant finning or fanning I explored the edges of comfort to see how my rig would behave practically without an external bcd, all following bottom contours keeping a hard bottom below me. Outlined is the data and observations.

Relevant equipment: configuration:
Al80s filled to 3100psi
2/3mm full wetsuit size large, slim. I'm 6'2" 175lbs. (Suit closer to 1.5/2.5mm now due to use)
3mm booties (Newish)
Reduced my carried lead by 4lbs.

Dive profile, gas (SM independent doubles pressures rounded and reported as single manifold doubles pressures) and notes:

15ft, 3100psi. Comfortable respiration. Neutral without thought.

50ft, 2800psi. Deeper inhalation needed and breathing from the 'top part' of my full lung begins to be conscious.

65ft. 2800psi. Needing to breathe with lungs predominantly full (comfortable) to maintain neutral buoyancy. I drift for photography 6 minutes while breathing pattern becomes less intentional.

100ft, 2700psi. Can hover without feeling uncomfortably full but in exhalation there's a significant buoyancy change and uncomfortable to breathe at that rhythm.

130, 2700psi. Neutral still possible without packing inhalation but rapid drop when exhaling to breathe. The skip breath pattern of breath is unnatural and narcosis from suspected co2 is predominant.

145ft, 2600psi. Neutral with full feeling lungs. (not packing like freediving, just deep inhalation) finning needed on exhalation. Narced, needing to be negatively buoyant with occasionally finning to hold my place in the water column.

160ft, 2500psi. Narced, can't hold neutral buoyancy without forming the co2 headache and packing my lungs to somewhat uncomfortably full. Task loading for manual dual strobe photography notably challenging and most of my focus needed for maintaining depth and monitoring pressure. Accepting I'm negative and adopting out of trim finning to keep up for cruising. Neutral only for framing photos. Heading up to deco now.

30ft, 1200psi. Notice I'm breathing "normally" neutral buoyancy effortless and familiar. Eagle rays show up to soar and bank with me a while.

15ft, 800psi. Now needing to breathe shallower. Conscious I'm a little light but still within normal comfort.

15ft, 500psi. Breathing shallower, altered breathing pattern. Still neutral comfortably. I clear deco (plus 30 minutes for conservatism and photography) and free-flow the tanks down to near empty in shallow water.

10ft, 200psi. Neutral 1/4 exhaled. Comfortable inhale puts me positively buoyant. Light finning down to be happy.

Slow ascent to surface. Able to bob about comfortably with my head above water on a full breathe.

To those of you who made it through this reflective rambling piece, thanks for your attention.

Discussion welcome.

Regards,
Cameron

 

[Akimbo]

I can totally relate since that was how all of us pre-BC (as-in Buoyancy Compensator, not Before Christ) divers learned. It was easier when wetsuit material wasn't as compressible as it is now but picking up rocks near the end of the dive wasn't unusual. It was also common to adjust our weight belts by a a pound or two based on the anticipated depth of the dive. No safety stops also helped.

I suspect that is why wings are disproportionately preferred over jacket BCs by old school divers. It is like all that extra bulk, especially in our view, is unnatural or a loss of freedom.

 

[JamesBon92007]

Balanced rig: Neutral buoyancy limits with no bcd and related safety considerations. Curious what comfot limits others have who regularly dive without a bcd have and what gear configurations work well.

Sharing my observations from a test dive, not suggesting it should be emulated.

Short version: Balenced rig, Two al80s, 2/3mm wetsuit using only lung volume for buoyancy compensation. Comfortable at 65ft. Deco stop at 10' with 500psi also comfortable. Able to hold motionless neutral without uncomfortable breathing patterns or finning.

Longer version.
Remembering the streamlining and comfort of diving without a bcd combined with my newer found love for maintaining the ability to hang motionless without constant finning or fanning I explored the edges of comfort to see how my rig would behave practically without an external bcd, all following bottom contours keeping a hard bottom below me. Outlined is the data and observations.

Relevant equipment: configuration:
Al80s filled to 3100psi
2/3mm full wetsuit size large, slim. I'm 6'2" 175lbs. (Suit closer to 1.5/2.5mm now due to use)
3mm booties (Newish)
Reduced my carried lead by 4lbs.

Dive profile, gas (SM independent doubles pressures rounded and reported as single manifold doubles pressures) and notes:



15ft, 3100psi. Comfortable respiration. Neutral without thought.

50ft, 2800psi. Deeper inhalation needed and breathing from the 'top part' of my full lung begins to be conscious.

65ft. 2800psi. Needing to breathe with lungs predominantly full (comfortable) to maintain neutral buoyancy. I drift for photography 6 minutes while breathing pattern becomes less intentional.

100ft, 2700psi. Can hover without feeling uncomfortably full but in exhalation there's a significant buoyancy change and uncomfortable to breathe at that rhythm.

130, 2700psi. Neutral still possible without packing inhalation but rapid drop when exhaling to breathe. The skip breath pattern of breath is unnatural and narcosis from suspected co2 is predominant.

145ft, 2600psi. Neutral with full feeling lungs. (not packing like freediving, just deep inhalation) finning needed on exhalation. Narced, needing to be negatively buoyant with occasionally finning to hold my place in the water column.
160ft, 2500psi. Narced, can't hold neutral buoyancy without forming the co2 headache and packing my lungs to somewhat uncomfortably full. Task loading for manual dual strobe photography notably challenging and most of my focus needed for maintaining depth and monitoring pressure. Accepting I'm negative and adopting out of trim finning to keep up for cruising. Neutral only for framing photos. Heading up to deco now.

30ft, 1200psi. Notice I'm breathing "normally" neutral buoyancy effortless and familiar. Eagle rays show up to soar and bank with me a while.

15ft, 800psi. Now needing to breathe shallower. Conscious I'm a little light but still within normal comfort.

15ft, 500psi. Breathing shallower, altered breathing pattern. Still neutral comfortably. I clear deco (plus 30 minutes for conservatism and photography) and free-flow the tanks down to near empty in shallow water.

10ft, 200psi. Neutral 1/4 exhaled. Comfortable inhale puts me positively buoyant. Light finning down to be happy.

Slow ascent to surface. Able to bob about comfortably with my head above water on a full breathe.

To those of you who made it through this reflective rambling piece, thanks for your attention.

Discussion welcome.

Regards,
Cameron

You are a very thorough person

First off, (and I'm sure you know this) with twin AL 80s you will have a 10 pound buoyancy shift just from your tanks, not including any suit compression (which won't be huge since you were diving a 2/3. I'm a little out of practice because for the past few years I've been diving from dive boats and shore diving from Maui and a BC is required but I didn't use any kind of a BC for my first 44 years of diving. With a single steel 72 it's easy enough to weight yourself so you are neutral at the surface at the end of the dive with a few hundred psi of air left. Even with a 7mm Farmer John it's not that bad except at the beginning of the dive, at depth. In that case I was always a bit negative but after about 20 or so minutes of diving I could become neutral by breathing off the top of my lungs. With a single AL 80 I didn't think it was that much different but needed an extra four pounds of lead and, of course, the empty 80 has a little more positive buoyancy but when shore diving I don't need to hold a safety stop so it wasn't ever an issue.

On a dive trip last month I told the DM how much weight I needed and he gave me less. I ended up spending three minutes at 15 feet with no air in my lungs. I supposedly have a strange and extremely rare intestinal disorder where my intestines are filled with air all the time and therefore I am more buoyant than it seems like I should be.

My current solution, to satisfy the scuba police and to attempt to remain a bare bones diver, is a mini-back wing that I attached to my old-fashioned scuba backpack. It is a decent-quality snorkel vest (actually it's my second vest but the other one finally wore out) and it has around 15 pounds buoyancy when filled but since, with a single tank, I should ever need more that about eight pounds it's more than I need and it's just like strapping on an old tank and backpack. I over-weighted myself by ten pounds and filled it until I was neutral and it didn't look very inflated So far I have only used it once at Catalina Island and I never gave it a thought after initially putting a little air in it. Another reason I like this contraption is because I bought two supposedly-compact travel BCs and still had to bring a checked bag. With the backpack/snorkel vest I think I can get back to a carry-on only (plus my small backpack) but I will have to wash out my clothes more often because not many will fit.

Edit: I forgot about the safety considerations. Well, you can always drop your weight belt

 

[REVAN]

I dive without a BC all the time. I usually only dive a single AL80, but I have dove a 120 without a BC before. Smaller tank volume is easier. On a single 80, I never get that sensation of needing to over inhale to maintain buoyancy unless I messed up my weighting. That's rare, but it can happen. The last time, I thought I had a standard AL80, but it turned out to be something called a neutral 80. I dropped 4 pounds of ballast, and all was right again.

Many people don't really think much about the many ways BC's consume air. For me, discarding the BC is all about streamlining. That's why I'm only using single tanks these days. The more efficient I can swim, the less air I need. BC's consume air intrinsically from using them, but also from metabolic consumption to drag the damn things through the water. I can get so efficient in the water that the single 80 is almost always more tank volume than I actually need.

On my last dive, I did a big 1.6 mile search for hammerhead sharks and other big animals. I was hoping to find something really impressive to video. I ran out of bay to search before I ran out of air. After 90 minutes searching, I got out with 1100 psi still in the tank. It's amazing how long a tank can last when you aren't working hard to swim.

 

[JamesBon92007]

Many people don't really think much about the many ways BC's consume air. For me, discarding the BC is all about streamlining. .

Since I have never attempted to enter through the surf while wearing a BC I can't really say for sure, but it sure seems like it's going to cause a lot of drag and slow me down in situations where timing is important. And then there is the "air" thing you mentioned too!

 

[Coztick]

130, 2700psi. Neutral still possible without packing inhalation but rapid drop when exhaling to breathe. The skip breath pattern of breath is unnatural and narcosis from suspected co2 is predominant.

Sounds like you've hit the limit for 95% of divers that would go with a bc let alone without. But no, lets try deeper..

Narced, needing to be negatively buoyant with occasionally finning to hold my place in the water column.

Ya sounds like you found the limit by any reasonable measure. But no, lets try deeper..

160ft, 2500psi. Narced, can't hold neutral buoyancy without forming the co2 headache and packing my lungs to somewhat uncomfortably full.

Now it sounds like you're past safe limits.
30 feet deeper than where "predominant narcosis" set in, substantially negative, co2 building... I'm hoping you had a little weight to drop or a dsmb along...

Thanks for not exceeding you're personal limits Cameron. Please tell me you had a support diver for this experiment.

 

[RayfromTX]

Fascinating and thank you for sharing this with us.

He had a hard bottom under him so I assume that bailing on the experiment would mean settling to the bottom and breathing normally to clear the retained CO2. I'm not saying it is safe to experiment with this, that is not something I am qualified to judge. I will say that dropping 4 lbs would have made his deco stop more difficult but there are always rocks I suppose.

In my very limited experience, my concern would be crossing the line where the CO2 narc impaired my mental ability to recognize the level of impairment and deal with it, like the sleepy or drunk driver.

From what I can tell Cameron, your safety backstop was the hard bottom. What were you carrying in the way of lift, such as a dsmb that could have been inflated? Would that have been too much task loading at the point of your most serious narc? What was your thought for contingency? What was your previous experience that you built this experiment on?

Humor, at what point could you just take off your fins and walk out?

 

[Kharon]

Personally, I've found using a thin, manually inflated snorkel vest that has a dump valve (IST Adult Snorkeling Vest at SwimOutlet.com - Free Shipping) under my soft backpack/harness gives me a safety factor and still is every bit as streamlined as the soft backpack/harness alone. If I do need to inflate it, a wee bit or a lot, it's air that has already been used.

 

[JamesBon92007]

Personally, I've found using a thin, manually inflated snorkel vest that has a dump valve (IST Adult Snorkeling Vest at SwimOutlet.com - Free Shipping) under my soft backpack/harness gives me a safety factor and still is every bit as streamlined as the soft backpack/harness alone. If I do need to inflate it, a wee bit or a lot, it's air that has already been used.

I've given some thought to using that type of vest and it seems to have advantages and disadvantages. If they made one with pockets I'd probably give it a try Originally I was using a very old Voit vest which had a built-in CO2 inflator which was inside a snapped pocket plus had another snapped pocket opposite of it. The result, when attached to a backpack, was that I had two small "back" pockets. Unfortunately it started to come apart at the seams and although it was easy enough to re-sew the seams it still did not hold air as well as I thought was acceptable. On both snorkel vests I attached the inflator and dump valve from another BC so I have the option of oral or power inflation just like any other BC. I consider the dump valve more as an over-pressure valve because I would need to be in a head-down position to completely deflate it, but in an upright (ascending) position to deflate it using the oral inflator.

From my point of view, based upon my personal experiences, diving with no BC is not a problem unless you are in a situation where perfect neutral buoyancy is important (hovering over delicate coral reefs, inside a shipwreck, inside a cave). I find this to be tricky at the beginning of the dive with a single tank and I'm having trouble imagining how to accomplish it with doubles, particularly double AL 80s. In my mind, if diving with doubles, somehow the diver is going to need (or at least want) about five pounds of controllable positive buoyancy from somewhere. There may be a few of us with giant lungs and an extra five pounds of capacity but I'm not one of them Perhaps there may be a trick that I'm not familiar with other than carrying around a big rock at the end of the dive. I heard about a diver who carried a bucket which he inverted and filled with exhaled air and emptied as the dive went on. A bit cumbersome but it could work. Personally I find a plastic grocery bag to me more convenient. Bottom line: I think I'd pass on diving doubles without some kind of controllable buoyancy compensation.

 

[100days-a-year]

I have at least a dozen friends with 5000 to more 15000 dives solely on hard pack diving 72s 80s and all kinds of oddball steel and aluminum tanks.Bouyancy control based on wetsuit thickness and ditchable weight.