Question about “balanced rigs” and having all ballast unditchable

[MichaelMc]

When a cruise ship floats, part of it is out of the water

Huh. I understand Archimedes. I screwed up on the valve weight, but I do get Archimedes, and steel ships floating. Edit: if the 'buoyed by' equals the total object weight then it stays there, partiality out or all in at some depth. If the ship descends, the displaced and buoyed by increases, raising it. If that happens on one side, it rights the ship, based on righting moment. I understand Archimedes and ship righting moment architecture, much less just buoyancy.

Most descriptions of weighting suggest a surface test such as you described above, but as just a crude estimate to be refined by a proper SS test. I'm taking an exactly weighted diver. Is there an issue with that exactly neutral diver in my disaster scenario?

My neutral suited diver is perfectly neutral with near empty tank. That means they will float motion less just below the surface, or at any depth, with low air. That does not mean they can put their head out with out kicking or extra buoyancy, nor with their initial air load. So leaving their planning at having a balanced rig seems to leave them in a lurch.

 

[Dan_P]

AFAIU, in this thread it isn't. At least for me, having a bit of ditchable weight is just another tool in my toolbox. Me, I like having different tools available even if I don't use them at a specific time.

If I have to add weight to be properly weighted, I see no reason whatsoever not to be able to ditch that weight - or at least some of it. Depriving myself of that option seems... suboptimal to me.

On this end, I don't see a need to ditch, and don't want to risk accidental loss without what I perceive as a need, that's all.

 

[MichaelMc]

On this end, I don't see a need to ditch, and don't want to risk accidental loss without what I perceive as a need, that's all.

What of my *neutral* vacation diver? Rig is balanced - they can swim it up. Beyond that, they're neutral at safety stop with empty BC and low air, not negative. They have a neutral suit. Their bioprene is not minimal, so they have ballast, but none is ditchable, being told ditchable was a risk.

Wing failure at 30' on hot drop descent. Weak legs and fins let them swim 60 seconds to the surface against 5-6 lb. of a modest tank, *just*. Balanced rig got them up, with no risk from ditchable!

Head comes out, low, lost in the chop and waves, no sight of the boat. They keep kicking up the 5-6 lb. of air and the 3-4+ lb.(?) of head water weight. For however long they want to stay up, on their weak legs and fins.

How long? Before the boat sees and gets someone to them? They're barely visible. Can they tread high enough for the boat to notice? Or inflate a surface marker buoy, while treading past their max, and hold it up? How long before their buddy, swimming down, realizes they're missing, looks all around at depth, decides to ascend, and finds them in the waves?

They drown or ditch, rejecting reg from anxiety or over breathing, coughing in the chop, legs giving out. If they can ditch, they're low in water, but now floating and breathing.

Yeah, their legs and fins are weak, but all the surface work is beyond the demands defined by a - swim it up - balanced rig. And they're neutrally weighted, not negative. If they eliminated ballast, they'd struggle with every safety stop, that would be risky.

Do you see any need for keeping some of their ballast ditchable to get extra surface buoyancy? Or was that balanced rig enough? For this neutrally weighted diver.

 

[johndiver999]

I’ll

What of my *neutral* vacation diver? Rig is balanced - they can swim it up. Beyond that, they're neutral at safety stop with empty BC and low air, not negative. They have a neutral suit. Their bioprene is not minimal, so they have ballast, but none is ditchable, being told ditchable was a risk.

Wing failure at 30' on hot drop descent. Weak legs and fins let them swim 60 seconds to the surface against 5-6 lb. of a modest tank, *just*. Balanced rig got them up, with no risk from ditchable!

Head comes out, low, lost in the chop and waves, no sight of the boat. They keep kicking up the 5-6 lb. of air and the 3-4+ lb.(?) of head water weight. For however long they want to stay up, on their weak legs and fins.

How long? Before the boat sees and gets someone to them? They're barely visible. Can they tread high enough for the boat to notice? Or inflate a surface marker buoy, while treading past their max, and hold it up? How long before their buddy, swimming down, realizes they're missing, looks all around at depth, decides to ascend, and finds them in the waves?

They drown or ditch, rejecting reg from anxiety or over breathing, coughing in the chop, legs giving out. If they can ditch, they're low in water, but now floating and breathing.

Yeah, their legs and fins are weak, but all the surface work is beyond the demands defined by a - swim it up - balanced rig. And they're neutrally weighted, not negative. If they eliminated ballast, they'd struggle with every safety stop, that would be risky.

Do you see any need for keeping some of their ballast ditchable to get extra surface buoyancy? Or was that balanced rig enough? For this neutrally weighted diver.

Well if the vacationing diver just took a snorkel all would be well... (as if this thread isn't contentious enough) LOL On the other hand, it actually does address the issue you raise.

To be honest, I totally agree with you on the scenario above, the diver would be safer with 6 or 8 lbs of lead to drop versus having that much ballast in a non-ditchable configuration.

DonP makes the simple argument that the potential for accidental lose of ballast over-rides the benefit of being able to drop it. For no-deco recreational dives, with the potential to drop 4 or 8 lbs of lead, I think the benefits of being able to drop that much lead are greater than the negatives of accidental loss of lead, plus there are ways to configure ditchable lead that are very, very secure.

I remember reading about old time "tech" divers with thick wet suits (35-45 years ago) using 20 lb plus weight belts and using a standard nylon belt but using two standard metal buckles in series, so one buckle popping open or failing would not be an issue.

 

[rsingler]

OMS or Scubapro weight pockets:
Flap folds over pocket; Velcro holds the flap; heavy plastic buckle holds the velcro'ed flap.
And that's been criticized by other posters bc it takes an extra 4 seconds to release. Can't win, lol!
But it's some ditchable weight for me, for any configuration over 2mm. Never lost a pocket; can't expect I ever will. Unlike the students practising with my shop's Aqualung gear. Happens to one student in EVERY class. Usually just in the pool. Rarely, the ocean too.

 

[Dan_P]

What of my *neutral* vacation diver? Rig is balanced - they can swim it up. Beyond that, they're neutral at safety stop with empty BC and low air, not negative. They have a neutral suit. Their bioprene is not minimal, so they have ballast, but none is ditchable, being told ditchable was a risk.

Wing failure at 30' on hot drop descent. Weak legs and fins let them swim 60 seconds to the surface against 5-6 lb. of a modest tank, *just*. Balanced rig got them up, with no risk from ditchable!

Head comes out, low, lost in the chop and waves, no sight of the boat. They keep kicking up the 5-6 lb. of air and the 3-4+ lb.(?) of head water weight. For however long they want to stay up, on their weak legs and fins.

How long? Before the boat sees and gets someone to them? They're barely visible. Can they tread high enough for the boat to notice? Or inflate a surface marker buoy, while treading past their max, and hold it up? How long before their buddy, swimming down, realizes they're missing, looks all around at depth, decides to ascend, and finds them in the waves?

They drown or ditch, rejecting reg from anxiety or over breathing, coughing in the chop, legs giving out. If they can ditch, they're low in water, but now floating and breathing.

Yeah, their legs and fins are weak, but all the surface work is beyond the demands defined by a - swim it up - balanced rig. And they're neutrally weighted, not negative. If they eliminated ballast, they'd struggle with every safety stop, that would be risky.

Do you see any need for keeping some of their ballast ditchable to get extra surface buoyancy? Or was that balanced rig enough? For this neutrally weighted diver.

So the diver has a tank full of gas and that's what's keeping the diver "heavy".
But no more than the diver can manage on breathing alone (<3kg).
That is, the exercise here is to breathe and float.
That's literally it.

Now put that in contrast to every diver drowning from panic, not pressing their "go home"-button (release ditchable), getting an arterial gas embolism from relying on an uncontrolled ascent to solve stressful situations, DCS hit (albeit a lessor of evils in this context) and hitting traffic while running their uncontrolled ascends.

Look at the accident reports - people aren't dying from using a balanced rig + proper weighting method.
Conversely, try opening up an annual report, say DAN's 2016 one, press CTRL+S and type in "weight belt".

 

[MichaelMc]

So the diver has a tank full of gas and that's what's keeping the diver "heavy".
But no more than the diver can manage on breathing alone (<3kg).
That is, the exercise here is to breathe and float.
That's literally it.

Now put that in contrast to every diver drowning from panic, not pressing their "go home"-button (release ditchable), getting an arterial gas embolism from relying on an uncontrolled ascent to solve stressful situations, DCS hit (albeit a lessor of evils in this context) and hitting traffic while running their uncontrolled ascends.

Look at the accident reports - people aren't dying from using a balanced rig + proper weighting method.
Conversely, try opening up an annual report, say DAN's 2016 one, press CTRL+S and type in "weight belt".

8-10 lb from 5-6 lb. gas + 3-4 lb. head. Female average inspiratory reserve volume is 2.4L / 5.3lb. So breathing at the top of their lungs, they have the buoyancy and legs to stay head out. Barely. They had leg strength to get to the surface, that was your swim to surface balanced rig definition. But not to stay there for long. You want them keeping that effort up while hyperventilating? On their reg? Or in the chop at their swim it up work load? Not flushing CO2?

- I thought the risk was accidental loss? Now it is panic ditching at depth?
- You want to not give them ditchable options, because they might misuse them? That road can lead to taking away that BC power inflator, it is a lot more panic go home over nothing, than ditchable weight.
- Why suddenly AGE, would they not be swimming for the surface and breathing in either case, just lighter in one?
- Where did this overhead traffic come from? Wouldn't it just run over our low in the water hyperventilating diver?
- What DCS hit? That is fixable, and this is no-deco.

 

[johndiver999]

8-10 lb from 5-6 lb. gas + 3-4 lb. head. Female average inspiratory reserve volume is 2.4L / 5.3lb. So breathing at the top of their lungs, they have the buoyancy and legs to stay head out. Barely. They had leg strength to get to the surface, that was your swim to surface balanced rig definition. But not to stay there for long. You want them keeping that effort up while hyperventilating? On their reg? Or in the chop at their swim it up work load? Not flushing CO2?

- I thought the risk was accidental loss? Now it is panic ditching at depth?
- You want to not give them ditchable options, because they might misuse them? That road can lead to taking away that BC power inflator, it is a lot more panic go home over nothing, than ditchable weight.
- Why suddenly AGE, would they not be swimming for the surface and breathing in either case, just lighter in one?
- Where did this overhead traffic come from? Wouldn't it just run over our low in the water hyperventilating diver?
- What DCS hit? That is fixable, and this is no-deco.

The bolded sentence is definitely on point. People are going to be pressing the Jesus Take Me Home button on the BC way before they drop lead in a panic situation. Accidental loss of lead is a reasonable concern (although not too hard to address) but the fear that lead belts are going to be raining down to the bottom of the sea when the first big shark swims by a group of novice divers is probably not a major concern.

 

[Dan_P]

8-10 lb from 5-6 lb. gas + 3-4 lb. head. Female average inspiratory reserve volume is 2.4L / 5.3lb. So breathing at the top of their lungs, they have the buoyancy and legs to stay head out. Barely. They had leg strength to get to the surface, that was your swim to surface balanced rig definition. But not to stay there for long. You want them keeping that effort up while hyperventilating? On their reg? Or in the chop at their swim it up work load? Not flushing CO2?

- I thought the risk was accidental loss? Now it is panic ditching at depth?
- You want to not give them ditchable options, because they might misuse them? That road can lead to taking away that BC power inflator, it is a lot more panic go home over nothing, than ditchable weight.
- Why suddenly AGE, would they not be swimming for the surface and breathing in either case, just lighter in one?
- Where did this overhead traffic come from? Wouldn't it just run over our low in the water hyperventilating diver?
- What DCS hit? That is fixable, and this is no-deco.

To be clear, I don't have a problem with a diver opting for ditchable weight up to the weight of the gas, but if you want to advocate ditchable weight as a main solution with uncontrolled ascents as the solution mode, then accident reports are stacked against it (accidental loss, panicking divers not ditching weight, AGE, DCS, etc.)

Again, please do open up e,g, DANs 2016 Annual Dive Report, press CTRL+S and type in "weight belt".

 

[rsingler]

Why can't we both find room to agree here?
@Dan_P , you've told us we should be balanced, and I agree...when I'm diving in a 2mm. How nice to just be close to neutral all the time! Minus 6 at the beginning and 0 at the end. Minimal air required in bcd; easy to swim up.

A few posts back, you told us we shouldn't be diving more than a 5mm if we wanted to be balanced. It's drysuit time beyond that. Well, not everyone plunks down $1k to $3k for a drysuit, and there are a LOT of Nor Cal divers in 7/8's diving perfectly safely with ditchable weight. In fact, per capita, I'd bet there are as many buoyancy accidents with new drysuit divers as there are weight pocket accidents with new bcd divers. I might be wrong. My point is, wetsuit or drysuit, you need to use your equipment properly. And too much ditchable weight with an insecure system is wrong. But that doesn't make ditchable weight wrong and balanced right, when your only affordable solution is a wetsuit.

And in the post just above, you've told us that in the event of a wing problem at the beginning of a dive, we should be satisfied holding 3kg of negative buoyancy until the boat comes. That or sit on the bottom until we've used up enough air. I guess that means no 100CF tanks are allowed without redundant buoyancy.

A balanced rig is a great practice, but is not the most practical solution to every dive scenario. I wish you could at least grant us that.

Finally, your comment about runaway ascents suggests that perhaps you are not as well versed in "unbalanced" diving as you could be. Take a guy like me wearing a garden variety 7mm wetsuit and a steel 100 with a nice streamlined wing on a 5# steel BP. But oops! My wing fails at the beginning of a dive, when I'm 19# negative due to wetsuit compression at 100 ft. My buddy is someplace else.
I concede it: I'm "unbalanced". But let's assume I'm saving up for my doubles rig and drysuit, and just haven't gotten there yet. Bad on me.
Sure, I could blow my smb while kicking like mad on a wall dive and see if I could keep from descending much further during the time it takes me to deploy it. And I could hang on that 19# or more lift, kicking until I got shallow enough for wetsuit expansion to help me out.

But...really?

Dump 8 lb. Boom! I'm only 11# negative, and can kick that up with moderate effort, and as my wetsuit expands, it gets easier and easier.
But there's NO runaway ascent!
With wetsuit expansion, I become neutrally buoyant at 23 ft with a full tank. I hang there and collect my wits.
When I'm ready, it's an easy ascent from 23 ft to the surface, where I arrive 6# positive. That means with a full exhale on the way up, I'm rising with only 2# positive buoyancy, and have plenty of time to look out for all those speedboats. And floating there at +6#, I'm not having to hold up those 3 kilos waiting for the boat. I'll trade that for your $1000 drysuit.

How about we agree that for some situations, having ditchable weight works just fine! And next month, I'll be balanced right there with you in Bonaire.