Diving inverted profiles?

[amascuba]

Proceedings of Reverse Dive Profiles Workshop. -- Open the PDF at the bottom of the page.

Title: Proceedings of Reverse Dive Profiles Workshop.

Authors: Lang, MA
Lehner, CE

Keywords: reverse
Dive
divers
decompression
DECOMPRESSION SICKNESS
DCS

Issue Date: 2000

Publisher: American Academy of Underwater Sciences

Citation: Lang, M.A. & C.E. Lehner (eds) 2000. Proceedings of Reverse Dive Profiles Workshop. Smithsonian Institution, Washington D.C. 295p.

Abstract: FINDINGS:
1. Historically neither the U.S. Navy nor the commercial sector have prohibited reverse dive profiles.
2. Reverse dive profiles are being performed in recreational, scientific, commercial, and military diving.
3. The prohibition of reverse dive profiles by recreational training organizations cannot be traced to any definite diving experience that indicates and increased risk of DCS.
4. No convincing evidence was presented that reverse dive profiles within the no-decompression limits lead to a measurable increase in the risk of DCS.
CONCLUSIONS: We find no reason for the diving communities to prohibit reverse dive profiles for no-decompression dives less than 40 msw (130 fsw) and depth differentials less than 12 msw (40 fsw).

Description: American Academy of Underwater Sciences (American Academy of Underwater Sciences - Login)

URI: Rubicon Research Repository: Item 123456789/4244

Appears in Collections: American Academy of Underwater Sciences

 

[Garrobo]

Did anyone figure out what "tc246" suggested? I'm too lazy to do it. And "jeckyll", thanks for the always friendly comments.

 

[pir8]

I try to always do my deepest dive first. If logistics don't allow it I don't get all bent out of shape about it.

 

[amascuba]

Did anyone figure out what "tc246" suggested? I'm too lazy to do it. And "jeckyll", thanks for the always friendly comments.

Assuming air and a square profile; then you would have exceeded the tables even if you just did 105feet for 21 minutes. MDL/NDL for air at 100 feet is 20 minutes. If you followed the tables for your second dive alone you would have to use 110 feet for 25 minutes, which exceeds the tables by 10 minutes, which would give you around 15 minutes of deco. BUT I would take it that you didn't do a square profile and only spent a couple minutes at that depth. I haven't actually looked at the tables, just figuring it off the top of my head.

 

[Gene_Hobbs]

Proceedings of Reverse Dive Profiles Workshop. -- Open the PDF at the bottom of the page.

Thanks James!

Also of interest may be this paper:
McInnes, Edmonds, and Bennett. The relative safety of forward and reverse diving profiles. Undersea Hyperb Med. 2005 Nov-Dec;32(6):421-7.
RRR ID: 4059 and 2005 UHMS Abstract 1799

This paper had a letter to the editor that needs to be read with it:
Risberg. Letter to Editor: The relative safety of forward and reverse diving profiles. Undersea Hyperb Med. 2006 Sep-Oct;33(5):321.
RRR ID: 5008

St Leger Dowse, Gunby, Moncad, Fife, and Bryson. A PROSPECTIVE OBSERVATIONAL STUDY OF REVERSE DIVING PROFILES (RDP) IN UK FEMALE RECREATIONAL DIVERS. 2003 UHMS Abstract.
RRR ID: 1326

It is worth mentioning that 'Reverse profiles in the rat spinal cord model' will be presented at the "Decompression and the deep stop" pre-course of the 2008 UHMS Annual Meeting in Salt Lake City. Frans is one of the best speakers I have even seen so it should be an interesting presentation.

 

[ianr33]

My Aeris computer does not like big reverse profiles. On a couple of occasions I have done an 80-100 foot dive followed an hour or two later by a 130 foot deco dive. The computer starts asking for huge amounts of deco. As these dives were planned/checked on V-planner I felt O.K about ignoring most of the deco.

My take on this is that the manufacturer does not really know what to make of these profiles and so pads them with a huge amount of conservatism.

My computer wont get me hurt doing reverse profiles,but the second dive is going to be very short if kept within NDL's

 

[Garrobo]

Evidently, the tables are screwed up.

 

[ianr33]

Could you explain that assertion in a little more detail please? I am afraid that I might get bent.

 

[Gombessa]

I believe GUE's tech training also holds the position that there's nothing fundamentally wrong with reverse profiles, and that dive planners and computers are adequately accounting for them.

 

[jeckyll]

I believe GUE's tech training also holds the position that there's nothing fundamentally wrong with reverse profiles, and that dive planners and computers are adequately accounting for them.

You just used GUE and computers in the same sentence. That's probably not ideal

Seriously, I think there is a difference in tech and recreational that doesn't transfer well. IN tech you assume that you do not have access to the surface for emergencies and a "proper" ascent with stops is involved in every dive. Unfortunately, in recreational you can't count on that.