Let's talk about balanced rigs

[maged_mmh]

That's the tip of a big iceberg of what's wrong on internet forums generally. Many forums, including this one, have their share of cyber-expert-know-it-alls. Many such comments, however, are made with good intentions even if they're not always right on the mark. I can understand that this irritates you. I have a similar pet-peeve when I read posts from someone with an obvious skills issue and someone tells them that they have to change their gear.

Newbie: "I can't hover"
cyber-expert-know-it-all: "you need a backplate and wing".
me: (rolls eyes)

kind of the same thing, I guess.

R..

http://www.scubaboard.com/forums/basic-scuba-discussions/278275-survival-kit-basic-divers-sb.html

 

[Slonda828]

Well I guess I am misunderstanding something then



That's not what's happening when you weight yourself correctly. If you're neutral at 10-15 feet with a near-empty tank and no gas in your wing (and minimal air in your drysuit, if that's what you dive), then you're properly weighted (at least at the end of your dive--weighting considerations at the beginning are another thing).

I'm just contending that the mechanism offered (slow expansion of wetsuit bubbles) is not the actual reason why you end up neutral in such a case.

You must be confused. Read what I am about to write, several times and aloud if neccessary:

When I dive with an AL80, I weight myself to be neutral at the surface with a FULL tank. This means I will be positive by about 3 lbs when I have about 500 PSI of gas left in my mostly empty tank. Ceteris paribus, this would mean that I would be light at my safety stop. I am not though, because my wetsuit has compressed enough to compensate for this fact. That is all I am saying. This is different from how most people weight themselves with an AL80 in a 3mm wetsuit.

In application it means that I have a 3mm wetsuit that takes 5lbs of lead to sink (without any scuba gear on). I know my NTEC rig is 2.5 pounds negative, and my regs are 2 lbs negative. This gives me 4.5 pounds of ballast. A luxfer AL80 is negative by 1.4 pounds full. I start the dive weighted to be neutral in this setup, so we'll call it "0". Now, I have consumed 2500 PSI of gas, so my AL80 (ballpark) is about 3.5 pounds positive. Why do I not blow my safety stop? Two reasons. One, I control my breathing. Two, my wetsuit has compressed from depth, making me neutral at my 15 foot safety stop. This is verifiable via experience, as I cannot weight myself in this fashion when diving in just shorts (without a wetsuit), because the buoyancy swing it too large and my lungs cannot compensate unless I short breathe, which I do not feel safe doing.

Is there anything at all about what I just wrote that you do not understand?

 

[Cave Diver]

You must be confused. Read what I am about to write, several times and aloud if neccessary:

When I dive with an AL80, I weight myself to be neutral at the surface with a FULL tank. This means I will be positive by about 3 lbs when I have about 500 PSI of gas left in my mostly empty tank. Ceteris paribus, this would mean that I would be light at my safety stop. I am not though, because my wetsuit has compressed enough to compensate for this fact. That is all I am saying. This is different from how most people weight themselves with an AL80 in a 3mm wetsuit.

Seems perfectly clear to me.

It's not the way I'd approach it, but if you understand the concept of weighting and neutral bouyancy and that's the way you choose to achieve it, it's not up to me to tell you differently.

 

[Slonda828]

Seems perfectly clear to me.

It's not the way I'd approach it, but if you understand the concept of weighting and neutral bouyancy and that's the way you choose to achieve it, it's not up to me to tell you differently.

I agree. It seems Goombessa needed clarification, so I did my best to remediate him. Cave Diver, I particularly like the fact that though we share different views on how to achieve neutral buoyancy, we did not begin the whole "my way is better!", "no, my way is better!" thing. I like when these discussions cover different views on things like a balanced rig, weighting, buoyancy, etc. This is what helps divers.

 

[Cave Diver]

Cave Diver, I particularly like the fact that though we share different views on how to achieve neutral buoyancy, we did not begin the whole "my way is better!", "no, my way is better!" thing. I like when these discussions cover different views on things like a balanced rig, weighting, buoyancy, etc. This is what helps divers.

Yes, that tends to get counter productive rather quickly. It's not important that a diver believe in my philosophy on diving, but rather how I came to those conclusions. What is important is that they understand the concepts, the theories and the practical applications behind my decisions so they can draw their own conclusions.

When I see someone who comes to a conclusion without the comfort of thought, I tend to argue my viewpoint rather passionately. But it's more to make them think about their decision than to convince them mine is correct.

They may decide that I'm an oracle, an idiot, or somewhere in between. The fact that they came to an informed decision is what's important.