PADI Inadequacies

[raybo]

Looks as though Stephen was right. Don't know why I thought not. :bonk:

I found this site Altitude Dive Table . It appears to support Stephen Ash's concept of simply using the highest expected elevation anticipated after diving, and use it to run the tables.

Walter? Mike? Is that what you interpret the "directions" at the bottom oif this link to indicate for procedure.

Do you agree with it, conceptually, that ascending immediately after diving would be be safe?

The only situation that I could see where this wouldn't be adequate are a few very high passes in some of the western mountain states. Not real likely, but if it's where you live, and you want to dive....

 

[GreenDiverDown]

raybo once bubbled...
Looks as though Stephen was right. Don't know why I thought not.

Dude, I'm not sure of that idea...I just brought it up to talk about.

I have heard of some folks doin' it that way. Roakey, our Colorado dive guru, says he has used that method...I'm sure that he is a better source on altitude diving than I. Don't forget...I live in the 'Valley of the Sun'.

SA

 

[MikeFerrara]

raybo once bubbled...

Walter? Mike? Is that what you interpret the "directions" at the bottom oif this link to indicate for procedure.

Do you agree with it, conceptually, that ascending immediately after diving would be be safe?

It seems reasonable. With the exception of the NOAA manual most texts I have seen recommend the rules for flying after diving.

 

[MikeFerrara]

ABQdiver once bubbled...





I would like to have the names of the books to satistfy my own curiousity about the subject. Can you name a few?

Thanks

The PADI advanced OW manual and the NOAA diving manual have theoretical depth charts. The PADI encyclopedia has some stuff but I don't remember how much (I'm not near my books now). I am sure that manuals from other agencies have it also. One of BRW's books may have the math. Also a number of sites on the web have this info also. Do a search on altitude diving.

 

[raybo]

Stephen Ash once bubbled...


I have heard of some folks doin' it that way. Roakey, our Colorado dive guru, says he has used that method...I'm sure that he is a better source on altitude diving than I. Don't forget...I live in the 'Valley of the Sun'.

I know. I just stumbled across that site.

Mike Ferrara once bubbled...

It seems reasonable. With the exception of the NOAA manual most texts I have seen recommend the rules for flying after diving.

It's seems reasonable to me as well, but it's almost too simple. that's why I questioned it in the first place. There's still got to be a way to determine the actual surface interval prior to departure and use the actual dive site elevation to plan dives.

I live in a place where I will change alelvation anywhere from 1000 to 5000 feet form my front door in less than 90 minutes. Just depends on which direction. It behooves me to understand this subject, and I'm just getting started in to in depth.

I posted that same link to that site on a new thread to Dr. Deco to get his input on it.

 

[GreenDiverDown]

Something about that method seems wierd...

Its like continuing the dive until you drive over that pass... but you stop keeping track of your dive time before you even get out of the water(you know...at the beginning of your ascent).

And looked at another way and taken to the extreme...

Potentially you could make a dive at 2000 ft. calculate it as if you were at 10000 ft. then hop in the car and make that 8000 ft climb.
Well that doesn't seem right... you've just figured a way to fly immediately after diving.

I don't think anyone has it figured out yet...not enough data.

I suppose you could stick to NOAA tables and use their ascent to altitude chart.

OR

Treat driving to altitude with the same respect as you treat flying.
The question then becomes...at what elevation does that plane take off! In other words...at what elevation is the pass too high to climb...2000 ft. 1000ft. 500 ft.

SA

 

[MikeFerrara]

It's the same situation as one encounters when flying after diving or...ascending to an even shallower depth. I would expect the way to calculate it is by using the same decompression model used to generate the table you are diving. The NOAA manual gives a chart based on showing required surface interval based on presure group and the change in altitude. This would seem to suggest that the answer is in the decompression model thus not a simple calculation like theoretical depth.

 

[raybo]

but in a sort of rational way if you thnk about it long enough.

Stephen Ash once bubbled...

Potentially you could make a dive at 2000 ft. calculate it as if you were at 10000 ft. then hop in the car and make that 8000 ft climb.

What your really doing is makking a rreeaaalllyy slow ascent from depth. with this metthod if you think about it. I think I saw somewhere to use 2 fsw for each thousand feet of air. so an 8000 foot ascent in air would essentially be an ascent from a shallow depth of something like 10-15 fsw adjusted for altitude (your "depth" at the dive site surface based on using the pass summit as your "surface"~ I'm sure technically it's pretty complicated,but you get the drift?)

So if it takes you an hour to reach the summit, and just for simplicity sake, it mathematically works out that the elevation change in air amounts to 10 fsw, then your last hour of the dive is at an ascent rate of .1667 ft/min. well within any recommended ascent rate I know of!

Given your plan is for the max altitude, and you will not have been ongassing for the lasst hour, but actually off gassing, you built in some conservatism in you plan, and the Si to the summit helos even more.

So, after some thought, it does seem to make some twisted sense.

 

[GreenDiverDown]

Warning...7% grade ahead...trucks pulling trailers use lower gears!

So what is your ascent rate if your driving a Ferrari?

SA

 

[raybo]

Got a reponse on the thread I started in the Dr. Deco forum. Indicationis that the Navy Manual has a table for this.

Mike Ferrara bubble...

This would seem to suggest that the answer is in the decompression model thus not a simple calculation like theoretical depth.

I aggree. I din't intend to imply that. But I think you stillhave to do the theoretical depth to determine use in the decompression model.

I've had a Navy manual on order for a while. should be here any day. Guess it'll make for interesting reading.

Thanks guys