double tank weighting issue?

[Thalassamania]

Having talked to (three) buddies who've been tangled in gill nets (this is the NE after all), they've all said the last thing they would have ever wanted to do was ditch gear. All thought that would have made it worse. In two cases they called in a buddy, the other took time to cut himself out. He said it was dicey. He was sure he would have died had he removed his gear. Different views I guess. Gill nets scare the crap out of me (especially the chance of coming across one mid-water; just another reason to avoid drifting deco in the NE).

I'd suggest that might be because they were not neutral in the way in which I describe. I've had to get out of gill nets more than a few times and I can guarantee you that if your rig is neutral, and you are neutral, and you have a long hose it is not a difficult thing to do if you move slowly and work methodically. YOU MUST NOT THRASH ABOUT! I try and keep my buddy out of the act, unless they see that I am screwing up.

We've also played with this in the pool, if nets are a concern for you I highly recommend that you do the same. We found that you need need to be careful about every buckle on your body, they are all potential traps, your fin straps (though not the springs that I use), your mask strap (slap straps really do have a reason to exist), tank strap buckles, weight belt buckles, etc. Tank valves are the worst, especially slingshot valves and H-valves (and forget about J-valves!). Tools secured to a belt, your regulators (side breathers like the OMEGA II and Cyclon 300 were less likely to foul, the issue is the exhaust tee), your power inflator, even your knife. The list is almost endless.

Why am I so focused on this issue? Pretty simple. First I had to cut a few divers out of nets. Second, on many cruises that I've made, the ship has got a net in wheel. Maybe its just that I'm an albatross, or maybe its just that when there are divers aboard the Captain would rather risk them than risk the shaft seals and bearings, I don't know. Every time that I've undertaken this task I've had to deal with getting fouled. Often it was simple and could be solved with a single snip, other times (esp. when it took me unawares from behind) I needed to get out of my rig. But I've been thorough it often enough and found it scary enough that I put a fair amount of effort into the question. The bottom line, for me, is neutral diver and neutral tank, minimum entanglement locations and multiple cutting devices that are secured to me so that I can not drop them.

 

[Thalassamania]

As far as ditchable weight is concerned, we need to recognize that we are dealing with contradictory sacred cows. Open water divers have grown up in a tradition of having ditchable weight avaliable as a last resort. On the other hand cave divers (and face it, DIR is decedent from cave diving) quite reasonably see ditching weight as tantamount to suicide.

 

[nereas]

As far as ditchable weight is concerned, we need to recognize that we are dealing with contradictory sacred cows. Open water divers have grown up in a tradition of having ditchable weight avaliable as a last resort. On the other hand cave divers (and face it, DIR is decedent from cave diving) quite reasonably see ditching weight as tantamount to suicide.

I completely agree with the above.

There is a major flaw in DIR theory in their assumption that cave diving protocols are always appropriate to open water. They teach this, yet it is untrue. They believe it, yet it is false and misleading and dangerous.

It should be self evident that going into a fresh water cave is worlds apart from diving in the open seas. Yet to DIR it is no different at all. Funny thing. (Funny = sad.)

 

[cool_hardware52]

As far as ditchable weight is concerned, we need to recognize that we are dealing with contradictory sacred cows. Open water divers have grown up in a tradition of having ditchable weight avaliable as a last resort. On the other hand cave divers (and face it, DIR is decedent from cave diving) quite reasonably see ditching weight as tantamount to suicide.

I disagree.

Ditching weight in an overhead is not a viable solution, however it's not much of plan in open water with virtual ceiling either.

If you ditch your ballast in order to become positive at depth, an uncontrolled ascent is almost a certainty.

This thread concerns weighting for double tanks. Doubles imply mandatory decompression.

Recognizing that ditching ballast with a deco obligation is unsound, the concepts of a "balanced rig" (which in practical application means avoiding being overweighted) and redundant buoyancy, i.e. wing + drysuit, or wing + lift bag is taught as a means to provide an acceptable level of safety without dropping any ballast.

In short one needs to weigh the consequences of an uncontrolled ascent against the "complexity" of redundant buoyancy. With a wing and drysuit the redundant buoyancy requirement is met with gear already necessary for many dives that require doubles.

Tobin

 

[limeyx]

I completely agree with the above.

There is a major flaw in DIR theory in their assumption that cave diving protocols are always appropriate to open water. They teach this, yet it is untrue. They believe it, yet it is false and misleading and dangerous.

It should be self evident that going into a fresh water cave is worlds apart from diving in the open seas. Yet to DIR it is no different at all. Funny thing. (Funny = sad.)

Maybe you could post your thoughts on what parts of the DIR system are dangerous in open water, and how it is so specific to caves, and also a review of which classes you've taken (GUE and non-GUE), to demonstrate your first-hand knowledge, rather than hearsay.

I am truly interested.

 

[JeffG]

I completely agree with the above.

There is a major flaw in DIR theory in their assumption that cave diving protocols are always appropriate to open water. They teach this, yet it is untrue. They believe it, yet it is false and misleading and dangerous.

It should be self evident that going into a fresh water cave is worlds apart from diving in the open seas. Yet to DIR it is no different at all. Funny thing. (Funny = sad.)

There is a major flaw in your assumption that DIR dictates using Cave protocol in open water.

But I guess you didn't have enough time to google that, now did you?

 

[JeffG]

Recognizing that ditching ballast with a deco obligation is unsound, the concepts of a "balanced rig" (which in practical application means avoiding being overweighted) and redundant buoyancy, i.e. wing + drysuit, or wing + lift bag is taught as a means to provide an acceptable level of safety without dropping any ballast.

Not necessarily.


There is no "rule" that says you cannot drop ballast. That is not a part of a balance rig.

In fact, for some rigs to be balance, they may need ballast that has to be dropped.

 

[24940]

There is a major flaw in your assumption that DIR dictates using Cave protocol in open water.

But I guess you didn't have enough time to google that, now did you?

Welcome back.

 

[nereas]

I disagree.

Ditching weight in an overhead is not a viable solution, however it's not much of plan in open water with virtual ceiling either.

If you ditch your ballast in order to become positive at depth, an uncontrolled ascent is almost a certainty.

This thread concerns weighting for double tanks. Doubles imply mandatory decompression...

And there are many doubles circumstances that do not imply decompression, Tobin.

Redundancy for solo diving is one such example, as I am sure you are aware. Maybe you just forgot about it for a minute.

Extended NDL diving at shallower depths is another example.

Surface swimming after scuba is a third example.

And the pre-deco phase of a deco dive is a fourth.

Do you remember "plan your dive & dive your plan"?

Every dive can be different from the previous.

Planning implies thinking. And thinking implies configuring properly.

I do not believe smart divers go into the water without any ditchable weight.

However I do believe a lot of non-smart divers like to joke about ditchable weight. And the Grim Reaper is laughing hardest at their jokes. And he is waiting for them.

 

[cool_hardware52]

Not necessarily.


There is no "rule" that says you cannot drop ballast.

True, that's the basis for "double al 80's in a wetsuit in the Ocean" This almost certainly requires a weight belt.

In fact, for some rigs to be balance, they may need ballast that has to be dropped.

Also true. However...

If you have redundant buoyancy there is no need to drop ballast.

If you do not have redundant buoyancy, for example a wing + wetsuit, and drop ballast to establish positive buoyancy at depth, you may no longer be able to make a controlled ascent.

Recognize the risk being assumed and pick your poison.

Tobin