Question about “balanced rigs” and having all ballast unditchable

[MichaelMc]

Diving negative is making your buoyancy control harder. And you have no reason that you need to be.... Its borrowing a necessity from some diving, carrying lots and lots of air, to conditions where it is not a necessity. Even safety issues aside of no ditchable and being negative on the surface when you forgot to turn the valve on.

Edit: You're discarding a safety feature for no benefit, and actually a cost in buoyancy control, you have no risk if you lose a pocket with half your 2-4 lb. ditchable. Yeah, that's not a lot ditchable, but that is all you have, for those tanks at least, AL or LP you would have more.

 

[Dan_P]

What do you mean 'won't scale anywhere'? And I mean ditchable weight, like integrated pockets or weight belt, not specifically just weight belt. Staying in rec. diving.

The tropics for low body fat people, not always the vacationer or local norm, who still care for no wetsuit, and want lots of gas, and in uncommon steels are a problem. That may be a big worry, but it does not leave the rest of rec. dives as 'won't scale anywhere'.

What I mean is, yes, absolutely, it's possible to do an entry-level dive in a wetsuit and with whichever BCD and ditchable lead. No problem.
When you go to AOWD-level, 30m, the bouyancy swing on your wetsuit (unless it's very thin) is so great that you're now relying on your BCD to work. If it doesn't, your only option now is to drop your lead and run an uncontrolled ascent.

That's at about day 5 of many rec divers' careers.
Nevermind tech (though obviously, pretty much no-one diving tech does so in a jacket-style BCD, which could serve as a reasonable indication).

In addition, you're looking at increased risk of accidental loss of ballast and subsequent uncontrolled ascent.

Hence, outside of a relatively narrow area of application, it won't scale anywhere.

 

[Bob DBF]

When you go to AOWD-level, 30m, the bouyancy swing on your wetsuit (unless it's very thin) is so great that you're now relying on your BCD to work. If it doesn't, your only option now is to drop your lead and run an uncontrolled ascent.

Without a BC at 30m if I drop my weight belt, I'll be staying there until I kick up, as a matter of fact I could dump all my gear and still not become buoyant, which is an actual problem. Somewhere around 50' or less the wetsuit will regain positive buoyancy over the rest of the ascent, which can be controlled by kicking down, or going horizontal.

The only way to have an uncontrolled ascent is to have air in the BC and not deal with it on the ascent.

The real problem is not having enough weight to drop and not being able to overcome your negative buoyancy, after you drop the weight, to swim up.

In addition, you're looking at increased risk of accidental loss of ballast and subsequent uncontrolled ascent.

Although in the past 50+ years of diving I have never lost a weightbelt, I understand it could possibly happen and act accordingly. An uncontrolled ascent would only happen if one did not take corrective action.


Focusing on the dreaded uncontrolled ascent avoids the actual issues involved. Seems the discussion won't scale.


Bob

 

[Dan_P]

Without a BC at 30m if I drop my weight belt, I'll be staying there until I kick up, as a matter of fact I could dump all my gear and still not become buoyant, which is an actual problem. Somewhere around 50' or less the wetsuit will regain positive buoyancy over the rest of the ascent, which can be controlled by kicking down, or going horizontal.

Hi Bob,

What are we talking here, a jacket-style BC, steel 12L, 7mm wetsuit and - say - 6kg of lead, at 30m?

You'd have to swim down almost 6kg of positive boyancy to maintain your stop and to dodge any surface traffic (which you obviously won't be able to see while swimming downwards).

I'd like to see a video demonstration of that, if you have the time and wouldn't mind

 

[CT-Rich]

Hi Bob,

What are we talking here, a jacket-style BC, steel 12L, 7mm wetsuit and - say - 6kg of lead, at 30m?

You'd have to swim down almost 6kg of positive boyancy to maintain your stop and to dodge any surface traffic (which you obviously won't be able to see while swimming downwards).

I'd like to see a video demonstration of that, if you have the time and wouldn't mind

You are confusing two unrelated problems. Maintaining a stop is irrelevant if you are ditching weight at depth. A safety stop is not required, just suggested. If you are in deco, you already made the decision, better bent than dead. Dropping lead at depth is not a decision to be made lightly. The last 20’ can put you at risk for an embolism as head to the surface. Boats don’t have any way of knowing whether or not you have a weight belt, so I am not sure how you become more likely to be run over.... The James method of diving away from machine gun fire and speed boats only works if you have a double “O” rating from MI-6.

 

[Dan_P]

You are confusing two unrelated problems. Maintaining a stop is irrelevant if you are ditching weight at depth. A safety stop is not required, just suggested. If you are in deco, you already made the decision, better bent than dead. Dropping lead at depth is not a decision to be made lightly. The last 20’ can put you at risk for an embolism as head to the surface. Boats don’t have any way of knowing whether or not you have a weight belt, so I am not sure how you become more likely to be run over.... The James method of diving away from machine gun fire and speed boats only works if you have a double “O” rating from MI-6.

Just like 10m/min is only suggested rather than 18, a safety stop is better and reduces risk of DCS - however, as you mention embolisms, I do agree that's a bigger problem, and one highly relevant also to uncontrolled ascents.
However, this is a choice one is making - if you want an option that doesn't work very well for controlled asends (namely the last portion of the ascend), that's your choice.

And I do agree boats won't see if you have a weight belt or not. Probably they won't even see you, particularly if they've already disregarded a dive flag. So do you want to be underneath one without the ability to stop, or be underneath one with the ability to stop, that's the question.

 

[AfterDark]

What I mean is, yes, absolutely, it's possible to do an entry-level dive in a wetsuit and with whichever BCD and ditchable lead. No problem.
When you go to AOWD-level, 30m, the bouyancy swing on your wetsuit (unless it's very thin) is so great that you're now relying on your BCD to work. If it doesn't, your only option now is to drop your lead and run an uncontrolled ascent..

Not everyone, my option to a non-operating BC is to open my safety pouch, remove my lift bag, clip it to my harness, fill it with air and begin a controlled ascent complete with SS. The option to drop a few pounds of lead from a pocket or two remains but lead is expensive these days so I'd go with a lift bag 1st option. And yes, I can do all that with only my pony bottle if need be.

A one trick pony in a sport with variables like diving seems strange to me.

 

[CT-Rich]

Do you know the saying: there are lies, big lies and statistics? Statistics don't proof your statement or the other way around fot that matter. Unless specific data about this issue is recorded (which to me seems almost impossible) there are a lot of opinions. Yours is one of them, others have other opinions

Statisctics won't convince me. And no, I don't object to ditchable weight, just have no use for it. So why not dive and let dive, ditchable weight or not. What's the issue here?

If you won’t believe Statists, you are just proof proof.

 

[AJ]

As long as statistics are used to prove an opinion I won't believe them. Statistics used in objective research are a whole other ball game. Statistics here are used to proof a point. So no, in this topic don't believe them. Prove me wrong with evidence and I will change my opinion

 

[Storker]

Statistics used in objective research are a whole other ball game. Statistics here are used to proof a point.

So what you're saying is that if I use statistics to reach a conclusion that's OK, but if I then use the same statistics to explain how I got to that conclusion you won't believe it?