Question about “balanced rigs” and having all ballast unditchable

[lowviz]

Balanced rig does not preclude ditchable weight. Being able to swim up your rig without a working BCD is not an unreasonable goal, but ditchable weight has nothing to do with it. .../...

???

Edit:
OK. Yeah, I think I get your point. But there could be times when it doesn't.

Newbs are reading this. IMHO, a TAD overweighted, practiced, and ditchable is a very good thing.

 

[johndiver999]

@seeker242, lovely description of the malevolent 'sweet spot'. Blow the stop. Just focus on a controlled ascent.

'Properly weighted' means that I have options that are reasonable. I'll do my stop on the surface on O2. Any diver who passed advanced nitrox has that very same ability. Few realize its worth.

Another important consideration is that at 25 or
30 feet you will still have a lot of suit compression. Stopping around 25 and doing a stop there is still beneficial and might be perfectly relaxed - depending on the suit and amount of lead ditched.

How much danger is really generated by accidentally loosing a belt when you have a rig that will allow you to hang comfortably at 30 ft after dropping.

 

[MichaelMc]

It seems as if balanced, with or without ditchable, is about getting to the surface. Open water safety ditchable is about easily staying on the surface.

So saying 'I'm balanced, so I do not worry about ditchable' is missing those being separate concerns, a bit too lightly. Unless it's followed by one of:
* I'm head out buoyant on the surface with empty BC and full tank(s),
(Edit: Having both head out full tank no-ditchable buoyancy and a low tank safety stop is hard!! You need about 10 lb. of suit compression between 0' and 15-20'. Roughly 5 lb. for the head out, and ~5 lb. for the low vs full AL80. My very very thick 20/10 wetsuit is still, a little, short of expanding that much. I was getting carried away. A much better description is RainPilot's below, which might leave neutral at surface with full tanks, due to wetsuit expansion, and the next two cases.)
* the air I'm carrying leaves me with no way of having optional ballast, or
* I'm diving cave/deco and ditchable adds an extra risk.

 

[lowviz]

@johndiver999, Yeah. You get it. It is all about an unconcerned and controlled ascent from an NDL dive.

It can be done so your PDC doesn't get upset and cost you a second dive or it can be done to just get you back safe and sound.

 

[seeker242]

@seeker242, lovely description of the malevolent 'sweet spot'. Blow the stop. Just focus on a controlled ascent.

Or, just move to FL and ditch all that neoprene

 

[johndiver999]

I would like to start out by observing that all the scenarios you paint involve multiple failures.

I will not be found in a situation where I am helping someone else and have such a small reserve left that inflating my BC or (orally) inflating someone else's BC is not feasible.



If that happens, I'll ditch my kit.



There are pros and cons. I take a holistic approach to buoyancy management. Unintended loss of ballast poses its own risks. I will not lose my ballast by mistake. I will not have my kit rocket to the surface if I take it off to try to free it from some fishing line or whatever. To gain these benefits, there are some situations where I am using no wetsuit or a very thin wetsuit, and end up diving without ditchable ballast or with very little ditchable ballast.



Well, anyone whose dive skills are such that a situation like that is likely, probably should dive with ditchable weight. And an instructor.

Trying to ditch someone else's weights at depth would be a last resort for me. Donate air, yes. Inflate their BC for them, yes. Swim them up, yes. Pull them up by inflating my BC, maybe as a last resort.



I always have the option to ditch my weight at the surface, because I can ditch my kit. It's an emergency, right? If my kit can't provide me air to breathe and cannot be made positive, it's of no use to me, so I'll ditch it and come back for it another day.

I've seen the eyes-glazed-over-can't-make-a-decision behavior. More than once. People in that "box" can't ditch their lead any more than they can inflate their BC.

I’m not arguing that a recreational diver must have ditchable
Lead. I definitely would not argue that you should carry extra lead, just so you have some to drop.

I don’t like to hear casual recreational divers talking about having no ditchable lead and seeming to not grasp the potential problems with that. The devil is in the details
So general statements are often inapplicable.

The issue I see is along the lines of people using a steel tank maybe a steel plate, a thick wetsuit and even more undroppable ballast. This to me, is inherently more dangerous than carrying 8 or 12 lbs of ditchable lead that might allow themselves to kick their way up from a bc failure.

I sometimes dive with no ditchable lead, but I feel more secure with the same rig, a thicker suit and 7 lbs on a belt.

True emergency air sharing events with expanding air in two bcs and in 2 suits and/ or wetsuits can be very tricky in a midwater ascent. One diver over inflating and another underinflating and an accelerated ascent can easily cause a buddy separation- possibly even intentional. And a victim really can sink away and without ditchable ballast, the prospects are very negative. Maybe you view that as a multiple failure scenario and as such not something to worry about, but it is not too far fetched.

 

[lowviz]

@seeker242, HA!! Not that easy.

Look at the difference between coldwater and warm water fish. I would melt...

 

[RainPilot]

The way I was taught (and teach) the “balanced rig” concept is as follows:

Determine the minimum safe ballast required to be neutral at the safety stop with an empty-ish tank and zero air in the wing.

Distribute that weight as required for trim.

Ensure that you have some of that ballast ditchable equivalent to the weight of the gas at the start of the dive.

BCD failure at start of dive, ditch gas weight ballast and you will be neutral. This allows for a controlled ascent.

At the end of the dive? Leave the weight alone allowing for a controlled ascent.

If you have any issues at the surface ditch the weight and then gear if needed.

IF you are correctly weighted you should be positive at the surface equivalent to your suit compression. You should never end up significantly negative at the surface.

 

[MichaelMc]

The way I was taught (and teach) the “balanced rig” concept is as follows:

Determine the minimum safe ballast required to be neutral at the safety stop with an empty-ish tank and zero air in the wing.

Distribute that weight as required for trim.

Ensure that you have some of that ballast ditchable equivalent to the weight of the gas at the start of the dive.

BCD failure at start of dive, ditch gas weight ballast and you will be neutral. This allows for a controlled ascent.

At the end of the dive? Leave the weight alone allowing for a controlled ascent.

If you have any issues at the surface ditch the weight and then gear if needed.

IF you are correctly weighted you should be positive at the surface equivalent to your suit compression. You should never end up significantly negative at the surface.

^^^^ this seems a nicely exact description of weighting, trim, ditchable, and surface buoyancy.

The possible problems start when the minimum safe ballast dwindles to less than the air. Or ditchable vs trim, unless you entertain less common ditchable methods such as ditch pockets on the shoulders, which are a difficult step to advocate for most BCs, and particularly for those without threadable 2” shoulder straps.

 

[chrispscott]

My answer is that it is a Doing it Right (DIR) term. "Balanced Rig" is a term that was probably coined by George Irvine. It has been continued by GUE as the President Jarrod Jablonski was also on the WKPP exploration with George. Equipment Configuration | Global Underwater Explorers

If you watch the video below it is still pretty relevent today (unless you despise DIR). In the video keep in mind that dive computers were closer to their infancy and weren't yet trusted but the rest is still relevant in my opinion.

Not to be too pedantic but this is from 1999. Dive computers were nowhere near being "in their infancy." The Orca Edge was released 15 years before that. Although to your point there weren't many computers geared towards the tech market at that point.