Diablo(Offline)

So some on tell me why the ACB system is'nt DIR

TobyFish(Offline)

a properly-balanced DIR rig should allow the diver to swim to the surface with no buoyancy and without ditching weight. this eliminates the NEED to ditch weight, so retaininng the FACILITY to ditch weight provides an unnecesary risk in terms of accidentlal weight-loss. However unlikely this may be, it is unnecesary and while in open water losing a small amount of weight may be a minor problem, in the caves where DIR was born it can be more of an issue. Sudden buoyancy may make you rise only a little, but this may be enough to lose the line, disturb roof silt (now find that line) and of course, you may need to go down before you can exit - losing a load of lead from an otherwise balanced rig could make this tricky

steve_cooper71(Offline)

I understand the concept of the balanced rig, I think. But if you have to swim up against, worst case scenario, full doubles, would this be possible for everyone, haven't tried it yet myself?? In the olden days tho didn't they consider the big pro 14 as ditchable weight, would it not be better to ditch some lead than your expensive torch.

I understand that you should, at most, only ever have to swim up the weight of whatever gas you have, I suppose with a He mix that should be pretty managable, but double 12 Ls full of air will be about 13lbs of gas I know you shouldn't be using air but if one did would it be possible to swim up against that sort of negative buoyancy?

regards,
steve.

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Alastair(Offline)

Hmm I didn't think ditchable weight was a big no-no. The canister light for instance has been described as part of your ditchable weight in the past. Personally I put most of my weight in v-weights but do have a weight belt for sea diving with 2kg in it which I could ditch in an emergency.

If your wearing a drysuit and cave diving then yes I'd agree you'd rather the weight in your set and have it non-ditchable. Your backup is then your drysuit if your wing failed. However diving open water in a wetsuit then being able to ditch some weight and swim your rig up seems sensible to me.

I wouldn't use the ACB though as a weight belt works for me when I need one and it doesn't get in the way of the canister light like the ACB pouches would do.

Cheers
Al

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Helium is our friend - GI3

montyg(Offline)

I don't claim to understand all the ins-and-outs of a balanced rig, but I can tell you this: in message number 2968 on the Gavinscooters list, George Irvine wrote:

"RE: [gavinscooters] Loaded Question.....

Ricardo, you are correct - the drysuit is not redundant buoyancy and should not be considered that in planning or balancing a rig. This kind of misconception could lead to adding too much fixed weight and then finding out the hard way what happens when you try to use the drysuit as your only source of inflation - it really gets ugly."

rgds
monty

Alastair(Offline)

Hi Monty,

None the less it's I'm pretty convinced it's what get's taught by GUE. The point about a balanced rig is that a diver should be able to drop weight and swim up without a functioning BC, a drysuit can help you do this. I agree it shouldn't be the sole mechanism.

There's a bit more detail in this doc:
http://www.gue.com/Equipment/Config/index.html

Cheers
Al

__________________
Helium is our friend - GI3