Staged decompression air only diving

[jbd]

I'm trying to decide if I want to get into staged decompression diving. Currently I have been looking at a set of Navy dive tables from a 1970 reprint of a book originally written in 1957. When I look at these tables I'm looking for dive profiles that I find acceptable to me. For the most part I'm not interested in deeper than 130 to 140. I'm not interested in hanging out for much more than 20 minutes at a given stop.

A specific example of my max from the tables.

Depth 140, Bottom time 30 minutes, first stop 5 minutes at 20 feet, second stop 21 minutes at 10 feet.

This set of tables uses the 60fpm ascent rate which I know has gone the way of the dinosaurs.

Is this an acceptable dive profile on air in this day and time?

I have not dove this profile and will not do any staged decompression diving until I get some specific training. As I said I'm just trying to decide if staged decompression diving is something I would do.

 

[ericfine50]

Why are you using air? How about Nitrox or even Tri-mix? For a deco gas think about 50/50 (50%02)? For training take a look at the GUE web site - www.gue.com

For tables - get a copy of a table computer program and use the different gases to A) get you out of the water faster and B) feeling better.

Eric

 

[Lost Yooper]

Navy tables are the absolute worst possible thing you could have gotten your hands on. They belong in a museum or something. They are a great example of what not to do. Download V-Planner for free and take a look at how deco should be, more-or-less, done. Chuck the navy tables.

http://www.coastnet.com/~powercheck/vplanner

You want to stay away from air diving. Nitrox and trimix are much better for you regarding deco.

V-Planner is easy to figure out and use, but if you have any questions, let me know.

Mike

 

[roakey]

To quote Irvine, the Navy tables "Bend you deep and fix you up shallow."

Programs based on all the new dcompression information out there don't bend you at all.

Roak

 

[padiscubapro]

Air deco diving is not a great idea, using the Navy tables is even a worse idea.. The navy accepts a certain percentage of divers getting bent. The worst are the 150 ft tables depending on the statistics you use typical incidence rate is 10%-15%, not exactly what I'd call safe..

For simple dives int the 130ish range Air as a bottom gas isn't horrible, a Nitrox mix would shorten your deco requirements, but at least a 50% mix for decoing is a must..

I see someone already recommended VPlanner, its a good program but should be run with a saftey margin incorporated, I personally use GAP www.gap-software.com with gradient factors turned on. For open ckt diving abyss software works well once you get used to the way it does repetitive dives, and its bailout too is pretty good. The current version is useless for a CCR diver. Gap and Abyss generally generate stop times longer than vplanner but a little extra hanging doesn't bother me.

 

[Lost Yooper]

Yeah, I have GAP as well. It's works, but I just prefer V-Planner's layout and ease of use. Whatever, so long as you understand deep stops and slow ascents -- especially the very slow final ascent. We can talk about this in depth if you come up this summer, JBD.



Mike

 

[Bob3]

GAP allows you the option to print out your profiles; haven't tried it on V-planner.
The USN tables have been redone a few times since the '70s,
the new ones aren't nearly as bad as folks are letting you believe though.
I suggest you do a couple things:
Download GAP (and/or V-planner)
download a new set of NOAA tables for comparison:
http://www.scubadiving.com/members/divetips.php?s=331

Those deep stops (GAP & V-planner) get rid of a whole world of microbubble mischief.

And for God's sake, use some enriched air in your gas; the difference it'll make may obviate the need for you to be walking with a cane (like me) years down the road.


If you have a slow connection & can't make the few meg download of the deco programs, PM me.