Average Depth Diving?

[MXGratefulDiver]

An excellent point. I would begin with the ascent from the safety stop... as an informal "survey" I decided several years ago to time folks from the safety stop to the surface. I timed hundreds and hundreds of them over 5 or 6 years, in the Gulf, in the Bahamas, in the Caribbean. Divers from all over the States and Europe and Asia. Even a few Aussies.
Average time??? Under 7 seconds, about 140 ft/min!

Learned behavior, Rick ... and it typically starts in the pool during OW class. How many instructors really force their students to take 20 seconds to come to the surface from the bottom of the deep end of the pool? Not many, from what I've observed.

... Bob (Grateful Diver)

 

[Thalassamania]

Yes indeed it does!

 

[TSandM]

This is something that's caused significant arguments in our household -- if Peter gives me the thumb, he goes up; even if we are at ten feet, I want to take a full minute to get to the surface. This results in our being ten feet apart, and a very mad husband when my head finally breaks the water, because I have "abandoned my buddy".

Looking at the relative pressure changes, it should be CLEAR that that last ten feet should be treated with respect. (Plus, she says with an embarrassed grin, I'm so proud of being ABLE to do that last ten feet slowly . . . )

 

[serambin]

I'm not sure about Luddites, but my issue with dive computers is that people often rely on them to the point where they stop thinking about what they're doing and just let the computer do their "thinking" for them. They often don't understand what the computer's telling them ... and it sometimes gets them into trouble.

Those who eschew computers are often doing so because they want to develop and maintain that understanding through practical application ... preferring to use their "built-in" computer in such a manner as to establish that understanding as part of their regular diving regimen.

It's not so much that computers are bad (I hope not ... I use one regularly) so much as that people have a tendency to use them to develop bad habits ...

... Bob (Grateful Diver)

On repetitive dives, especially when diving on consecutive days, I manually profile my dives and compare the results with my computer. Sometimes they vary a lot and sometimes very little. This tells me at least two things:

1. My computer isn't malfunctioning.

2. The amount of 'extra' bottom time I'm getting from the computer algorithm.

It also makes the SI go faster.


Stan

 

[serambin]

Yeah, but at least in those days we were supposed to be shooting for 60 fpm, following some mythical "smallest bubble" and so... had an excuse... sort of...
Oh, and it was more like 30 - 35 years ago, wasn't it??? Are we getting a little long in the tooth?
Rick

My PADI OW Manual was copyrighted in 2002 and it still uses the 60 fpm rule. However, it says "A slower rate is acceptable, and appropriate."

On one other point, where can we get information on the 'latest' best assent profile?

Stan

 

[MXGratefulDiver]

Something else worth noting ... different computers will supply you with different information.

I own two computers ... a Suunto Vytec and an Oceanic Versa Pro. Both are nice computers, but use different algorithms.

A while back, just for comparison purposes, I strapped them side-by-side on my arm and took them for a few dives. Regardless of dive profile, the Suunto was consistently more conservative ... on deeper dives, wildly so. On one particularly aggressive dive, the Suunto put me into deco while the Oceanic told me I still had 27 minutes of NDL.

That's why I don't "trust" my computer ... I use it to provide me with basic information, and use my own judgment to decide how to use that information.

... Bob (Grateful Diver)

 

[JimC]

This is something that's caused significant arguments in our household -- if Peter gives me the thumb, he goes up; even if we are at ten feet, I want to take a full minute to get to the surface. This results in our being ten feet apart, and a very mad husband when my head finally breaks the water, because I have "abandoned my buddy".

You aren't doing the abandoning.. he is.

 

[JeffG]

Well average deco isnt working for her either is it. She could start by seeing if switching from average depth deco to using a computer avoids this. It would be more scientific than her present method

(Try this again...I hate my laptop)

You are confusing Avg Depth usage with a Dive Profile created by Ratio Deco.

The dive profile wasn't working for her. Has nothing to do with avg depth. Given that Ratio Deco creates similar profiles to most modern deco software, that would also mean she would be incompatible to the profiles generated by them.

So which would lead me to believe that she would be incompatible with whatever deco algorithm that was in her computer.

Do you also assume that just because your computer shows a deco obligation and a 10' ceiling that one is supposed to pop right up to 10' ??

Charlie, we have been talking about mixed gas diving here.

 

[limeyx]

Well average deco isnt working for her either is it. She could start by seeing if switching from average depth deco to using a computer avoids this. It would be more scientific than her present method



Cmon this isnt a great advert for it
...

An advert would imply I'm trying to sell it. I honestly dont give a crud if people use the technique or not, as long as I have enough dive buddies to actually get out & go diving with.

Dive however the heck you want. (BTW the 5 mins was not necessarily "arbitrary")

 

[limeyx]

...

only an idiot would believe this is the way to go about solving the problem. err i had a bit of a twitch on the last dive, i will spend another 10 minutes on o2 next time, see if it works for me.

First off, I'd rather you not call me an idiot if you can possibly help it.
Second, how do you really think that tables are generated? Maybe not by exactly that method, but it's all experimentation and reducing the statistical chances of getting injured to a "small enough" number.

Second, go tell that to people who regularly save multiple hours of decompression by doing just that.