"Balanced Rig"

[John_B]

A bunch of DIR threads have been purged. So we may very well need to revisit some of these oft' talked about subjects.

 

[rjack321]

Didn't we lose everything here about 4 months ago in a big server crash? Or was I dreaming?

 

[Thalassamania]

Thal-
I guess then, diving a wetsuit where compression is an issue, you could not acheive this at all depths, correct?

Tom

Achieve it perfectly at all depths, no, Achieve it "close enough" to be able to deal with it within your breathing pattern ... yes within limits of your lung volume and the amount of gas you carry. Face it, if you're going to go deep, or dive bottles and don't believe in more than one buoyancy system (I love my Fenzy) then you'd best to a dry suit. Most of the folks I dive with do a dry suit with a weight harness.

 

[dumpsterDiver]

Thanks for the explanation. That was definitely the most complete discussion I've heard about the definition of a balanced rig.

As for ditchable weight:
1. you have to be able to drop enough to allow you to swim a full rig up to your first stop, but also
2. you have to make sure you don't ditch too much so that once you reach the stop, you will be able to hold it.
3. Making things more complicated, you will also be breathing gas and making yourself lighter.

So then the safest amount of weight ditchable would be roughly the weight of the backgas you breath on the bottom. This would allow you to ditch weight at the start of the dive, and still be able to maintain your stops even if a team member has some total OOA situation and winds up breathing off your backgas during your whole ascent.

If you lose buoyancy at the end of the dive, you should be able to safely swim up your rig since its lighter. If you can't swim up you rig after reaching your rock bottom turn pressure, then you aren't diving a balanced rig.

Sound roughly correct, or am I inferring too much?

BTW, the original definition I was told for a "balanced rig" was one where you weight yourself for neutral without your rig, also weighting your rig to be neutral when empty. This would allow both you and your unit to be neutral on the bottom even when doffing and donning. I don't remember the source of this, and it definitely was not a DIR explanation, but this is what prompted the original question.

Tom

I thought some of the discussions were excellent! However, I do not see the logic of saying that you should carry ditchable weight equivalent to the weight of the gas in the tanks.... I do not see the logic in that, With a very think wetsuit and deep depth and a single tank, somebody will expereince MUCH more bouyancy loss from suit compression than the air weight in the tank... yes?

 

[rainman_02]

I thought some of the discussions were excellent! However, I do not see the logic of saying that you should carry ditchable weight equivalent to the weight of the gas in the tanks.... I do not see the logic in that, With a very think wetsuit and deep depth and a single tank, somebody will expereince MUCH more bouyancy loss from suit compression than the air weight in the tank... yes?

Since diving deep on a single tank and/or thick wetsuit is not DIR, this is not a consideration.

 

[John_B]

Didn't we lose everything here about 4 months ago in a big server crash? Or was I dreaming?

:blush: Uh, brainfart on my part.

John

 

[b1gcountry]

I thought some of the discussions were excellent! However, I do not see the logic of saying that you should carry ditchable weight equivalent to the weight of the gas in the tanks.... I do not see the logic in that, With a very think wetsuit and deep depth and a single tank, somebody will expereince MUCH more bouyancy loss from suit compression than the air weight in the tank... yes?

I'm only trying to understand the "DIR" Philosophy on ditchable weight here. I never thought ditchable weight was DIR, but I guess I was wrong. If you do have ditchable weight, it would be limited to a fairly small amount though if you can drop it and still plan on completing your deco/safety stops. I was curious how they calculated how much is safe to drop if you are diving properly weighted in the first place. If you drop ANY weight at depth, then you are basically relying on the weight of your gas as ballast. That's a little scary to me, but I'm trying to understand it before I disagree with it.

Tom

 

[limeyx]

OTOH, searching for "Balanced Rig" in the subject in DIR only, gives no results.

I did search. I didn't find what I was looking for.

Hmm, referencing other people's posts, you may be right.
I thought that when the (latest?) legendary crash occurred we only lost relatively recent posts. In that case, please accept my apologies.

I did suggest a sticky DIR FAQ thread that would cover a bunch of this stuff back when the "DIR Practicioners zone" was created but there was no traction.

I still think a FAQ could work well. I know there is a tendency for people to always think the question in a FAQ "doesn't quite cover their situation", but even so, I think it would help answering certain issues that are pretty well "closed up" and not up for huge amount of real debate (unless something within DIR changes, or some revolutionary new piece of gear makes something vastly different)

 

[Ben_ca]

I'm only trying to understand the "DIR" Philosophy on ditchable weight here. I never thought ditchable weight was DIR, but I guess I was wrong. If you do have ditchable weight, it would be limited to a fairly small amount though if you can drop it and still plan on completing your deco/safety stops. I was curious how they calculated how much is safe to drop if you are diving properly weighted in the first place. If you drop ANY weight at depth, then you are basically relying on the weight of your gas as ballast. That's a little scary to me, but I'm trying to understand it before I disagree with it.

Tom

That's because you are in the mindset of "ditching weight" to be one of your first actions....

As much as I hate saying it.... Take the class... It'll explain it a lot better than learning online.

 

[b1gcountry]

That's because you are in the mindset of "ditching weight" to be one of your first actions....

As much as I hate saying it.... Take the class... It'll explain it a lot better than learning online.

Well, actually, no, the idea of ditching weight was not brought up by me, but by JeffG. If you look up above, he said something to the effect of "Sometimes you need ditchable weight to be balanced". I'm trying to figure out his rationale behind that, and what his guidelines are for determining how much ditchable weight he needs.

For the record, I have not dove with any ditchable weight for about two years. I convinced myself I didn't need it one day by dumping my BC with a full tank and actually swimming up to the SS from the 80' platform at Mermet...so my mindset is very much not in the "ditching weight first" camp.

As far as taking Fundies, I would very much like that. The problem is I'm in St Louis. The only instructor I've found within a 6 hour drive is a guy in Lexington, KY. I have emailed him asking to keep me posted as to his next class...but that's a separate thread.