Buddy Dive - bad attitude?

[MXGratefulDiver]

We are not just talking about tissue but also bone and muscle. Every aspect of the human body works to determine how much weight is needed to sink the body only. Lung capacity, stomach size etc..... I am not a physics professor but I did stay at a Holiday Inn Express last night and I know that variation can and should be expected with weighting. How much variation is another question. To say that James is overweighted at 26# with nothing else to support his number or that statement is not sensible IMO. There is way too much missing in the way of information to make a statement like that.

I'm not a physics professor either ... just a lowly dive instructor who has been helping a lot of different people figure out how to weight themselves properly over the past several years. In those years, I've lost a lot of the preconceptions I thought I knew about proper weighting ...

... Bob (Grateful Diver)

 

[MXGratefulDiver]

OK, so you don't disagree with the physics, just the physiology?

How do dive computers lump the possible variations and combinations of human tissue into a simple computation about nitrogen absorption?

Poorly.

A few years back I did several dives with two different computers strapped side-by-side on my right arm. One was a Suunto Vytec and the other an Oceanic Versa Pro. Over the course of those dives I noticed as much as a 28 minute variance in NDL's, depending on depth and time. I would intentionally take them over NDL to see what occurred on ascent ... noticing that depending on the dive profile, they rarely agreed ... one would usually start reducing required deco time while the other would continue adding to it.

Why is that, do you suppose?

Could it be because those two computers are based on algorithms that make different assumptions ... based on choosing different mathematical decompression models?

Certainly neither one knows a damn thing about my body.

Fortunately, I do.

But to answer your question ... dive computers rely on a concatenation of "safety factors" which are built into their algorithms ... allowing for those variances. In effect, they build enough padding into their deco calculations that it will accommodate almost everyone ... in most cases, well beyond what are actually needed.

... Bob (Grateful Diver)

 

[boulderjohn]

I am seeing here a difference in how people approach situations like this in general.

When I encounter someone whose credentials denote expert status, and that person says something that doesn't seem right to me, my reflexive action is to think I must be missing something. I might ask for more information. I might probe. I might research elsewhere. In more than a few such cases I have learned that I myself was mistaken in my initial understanding, and as a result of this careful approach I was rewarded by a deeper understanding of the principles involved.

Other people approach such a situation by telling the acknowledged expert that he is wrong and doesn't understand even the most basic principles.

Different strokes for different folks, I guess.

 

[paulw]

The weight person wants or needs is the weight they want or need and I just don't see the big deal everyone makes of it. NOW if they are attaching the weights with spring loaded suicide clips.. well those things will kill ya!

 

[Mossman]

I am seeing here a difference in how people approach situations like this in general.

When I encounter someone whose credentials denote expert status, and that person says something that doesn't seem right to me, my reflexive action is to think I must be missing something. I might ask for more information. I might probe. I might research elsewhere. In more than a few such cases I have learned that I myself was mistaken in my initial understanding, and as a result of this careful approach I was rewarded by a deeper understanding of the principles involved.

Other people approach such a situation by telling the acknowledged expert that he is wrong and doesn't understand even the most basic principles.

Different strokes for different folks, I guess.

If we all trusted experts, we'd still believe the sun revolved around the earth.

Blind faith, just because someone professes to be an expert, might work for you but it doesn't work for me.

Besides, I'm an acknowledged self-professed expert too, so my observations are just as valid.

 

[MXGratefulDiver]

I don't claim to be an expert ... most of what I post on this board is based on what has worked for me and the people I dive with. Your mileage may vary ...

... Bob (Grateful Diver)

 

[boulderjohn]

If we all trusted experts, we'd still believe the sun revolved around the earth.

Blind faith, just because someone professes to be an expert, might work for you but it doesn't work for me.

Besides, I'm an acknowledged self-professed expert too, so my observations are just as valid.

I didn't say I put my blind faith in experts. I said...

When I encounter someone whose credentials denote expert status, and that person says something that doesn't seem right to me, my reflexive action is to think I must be missing something. I might ask for more information. I might probe. I might research elsewhere.

For example, a couple of years ago John Chatterton said something about decompression theory in one of the tech forums that I thought was wrong. But it was John Chatterton. So I cautiously asked clarifying questions, and I reviewed literature to confirm my understanding. It turned out he was indeed wrong. We all came to that understanding through that inquiry process, rather than my flat telling him he was wrong.

 

[Mossman]

I don't claim to be an expert ... most of what I post on this board is based on what has worked for me and the people I dive with. Your mileage may vary ... )

See what I mean? I don't think either of us were considering you to be the expert, we're talking about someone else

I didn't say I put my blind faith in experts. I said...

For example, a couple of years ago John Chatterton said something about decompression theory in one of the tech forums that I thought was wrong. But it was John Chatterton. So I cautiously asked clarifying questions, and I reviewed literature to confirm my understanding. It turned out he was indeed wrong. We all came to that understanding through that inquiry process, rather than my flat telling him he was wrong.

That you did, I apologize. However, I did concede that said expert contacted me after my inquiries of how I could possibly be wrong. For one, we were comparing apples to oranges, as I was specific about weighting a 3mm suit.

Good for you to challenge Chatterton. He's an expert writer and wreck diver maybe, but what makes him an expert on deco theory? Just because one might be an expert diver doesn't make one an expert in all things diving-related.

Greg Mossman, SPBE (self-professed buoyancy expert)

 

[Ump06]

May I help. Long before I got into teaching SCUBA I taught swimming, lifesaving, etc. No weights, just a body with a swim suit. One of the requirements was floating for a period of time. During that period of time I discovered that life doesn't always follow norms. One of those norms being preached here is identical people of same weight and height float at the same level. Not true. Some sink to just a nose, others float with almost all the head out, and a whole lot in between. When I got into SCUBA I would council people as to were to start with weights and adjust from there. All the book learning in the world is not a substitute for the real world. The other thing floated about here is comfort level. Again, that is the real world talking. If you want a couple of extra pounds for whatever reason for your comfort go for it. Maybe your BC has a little pocket that is not easy to deflate. Whatever. Book learning and school learning are great, but just a complement to real world obtained knowledge.

 

[scubadada]

Did Buddy Dive have an attitude problem?--------------> infinitely long discussison on proper weighting, go figure.