driving to elevation after diving?

[Thalassamania]

Try this article for background:

At-Altitude Arithmetic

By Larry "Harris" Taylor

 

[robertarak]

...the same way you'd use conventional tables for multiple dives?

<shrugs>

If you are asking specifically about the Ascent to Altitude tables, you use the highest Repetitive Group (in the last 24 hours) for computation of your SI until moving to the higher altitude.


All the best, James

OH, you mean, actuallu open the second link to see the rest of (or back side) of the tables! DOH!

 

[RonFrank]

Try this article for background:

At-Altitude Arithmetic

By Larry "Harris" Taylor

Good article. Now I just need to determine if my computers take altitude into consideration when calculating depth because me thinks they do!

 

[Tigerman]

The lake we routinely dive here is at 5250 ft. I wouldn't be concerned with gaining 600-800 feet elevation.

Diving at and ascending to altitude is not quite the same thing. Doing altitude diving I hope youre aware of that..

 

[Thalassamania]

Good article. Now I just need to determine if my computers take altitude into consideration when calculating depth because me thinks they do!

Some newer computers do. I think Harris' piece predates.

 

[RonFrank]

Some of the responses to this question trouble me somewhat. I crossed the street 3 times against a red light and didn't get hit so you should be able to as well.........

This is just my personal opinion.

Dive Safe.

Steve

I like the analogy, but I don't think it fits. The science behind altitude adjustments is largely theory. My computer does penalize me for altitude, and I dive within those constraints. I'm also very aware of some of the fly time adjustments.

OTOH, every time we are at the Hole, there is generally well over 100 divers. Every one of them living in CO will hit over 8000 feet on the way home after a weekend of diving. None of them will off gas for more than a few hours before doing so.

To date I've not heard of ONE person getting bent doing this. If they want a test group, here it is. As I indicated, the Tech divers often hit over 200' on two dives, do NOT adjust for altitude in their deco scenarios, and they then drive home over an 8000' pass.

I would LOVE it if DAN, or some other agency wanted to do some studies on divers who dive at altitude on a regular basis rather than just working off theory.

As for the OP's question, I do shallow profiles in CO lakes (5280'), and then head home to 8950' a few hours later. I'm not even sure gaining 600' of altitude is something to consider.

Dr. Bill sited an example of someone getting bent by adding a 1600' altitude gain. The real question would be WHY did she get bent? There is a lot that goes into this mix, and a gain of 1600' may have had nothing to do with it.

 

[Thalassamania]

I like the analogy, but I don't think it fits. The science behind altitude adjustments is largely theory. My computer does penalize me for altitude, and I dive within those constraints. I'm also very aware of some of the fly time adjustments.

The science is far more than just theory, there&#8217;s a large group at Brooks Air Force Base that&#8217;s worked on this for years, in fact the originator of DAN, Col. Jeff Davis, M.D. was there and lots of empirical testing was done.

OTOH, every time we are at the Hole, there is generally well over 100 divers. Every one of them living in CO will hit over 8000 feet on the way home after a weekend of diving. None of them will off gas for more than a few hours before doing so.

To date I've not heard of ONE person getting bent doing this. If they want a test group, here it is. As I indicated, the Tech divers often hit over 200' on two dives, do NOT adjust for altitude in their deco scenarios, and they then drive home over an 8000' pass.

I suspect that the techies are managing only because of the mix that they&#8217;re diving and the oxygen their decompressing with. Clearly the other divers are likely not loading up on nitrogen very heavily and the time it takes them to the top of the pass is sufficient for them to out gas.

I would LOVE it if DAN, or some other agency wanted to do some studies on divers who dive at altitude on a regular basis rather than just working off theory.

As for the OP's question, I do shallow profiles in CO lakes (5280'), and then head home to 8950' a few hours later. I'm not even sure gaining 600' of altitude is something to consider.

Dr. Bill sited an example of someone getting bent by adding a 1600' altitude gain. The real question would be WHY did she get bent? There is a lot that goes into this mix, and a gain of 1600' may have had nothing to do with it.

Getting bent going quickly from a day of heavy duty diving at Catalina then driving past the airport at 1,602 ft. can, in rare cases, get you bent (there is a similar rise at Pacheco Pass, 1,300 ft., from Santa Cruz to Los Gatos) and it is only a drop in absolute pressure of about 5%. Going from 5,280 feet to 8,950 is on the order of 15% and thus should present a more serious challenge. When diving in Monterey we were required to do the ascend to altitude calculation for 2,000 feet if we were driving back over Pacheco Pass.

 

[pawclaws]

Safe ascents to altitude after diving are a rather controversial subject in my neck of the desert, Las Vegas. Some local dive shops sponsor trips to Southern California which leave Las Vegas in the morning and return immediately after diving. There is a 4700 ft mountain pass which must be crossed on the drive back.

Although I've never heard of any problems with any diver getting bent on the trip back, I do know that my LDS and instructor feel that it is dangerous and advises to spend the night and not risk it.

So quite a difference of opinion, depending on who you talk to.

 

[RonFrank]

The science is far more than just theory, there’s a large group at Brooks Air Force Base that’s worked on this for years, in fact the originator of DAN, Col. Jeff Davis, M.D. was there and lots of empirical testing was done.

Any links to this type of information?

 

[Gene_Hobbs]

Any links to this type of information?

The beginning of DAN's History linked here or here. Dr. Davis actually started the LEO-FAST program at Brooks Air Force Base. It was this idea of a 24 hour/ 7 day a week emergency line for divers that was later molded by Dr. Bennett into a NOAA grant and later into what is now the DAN we all know.

Jeff Davis was the co-author of the Bove and Davis' Diving Medicine book and MANY other hyper- and hypobaric research publications. He was a pioneer in the clinical use of hyperbaric medicine and the UHMS Gulf Coast Chapter gives away the Jefferson Davis Award yearly. The Hyperbaric chamber complex at Brooks Air Force Base is named in his honor as is the wound care center in San Antonio.

He oversaw the work of Dr. Bassett on:
Decompression Procedures for Flying After Diving, and Diving at Altitudes above Sea Level.
Bassett, 1982
RRR ID: 4531

and much of the work done by Dr. Sheffield:
Sheffield PJ (ed). Flying after Diving. 39th Undersea and Hyperbaric Medical Society Workshop.
UHMS Publication Number 77(FLYDIV)12-1-89. Bethesda: Undersea and Hyperbaric Medical
Society; 1989; 222 pages. RRR ID: 4256

You can find Dr. Davis' work in PubMed and Google searches but here are a couple more highlights:

Davis JC (ed). Treatment of Serious Decompression Sickness and Arterial Gas Embolism. 20thUndersea and Hyperbaric Medical Society Workshop. UHMS Publication Number34WS(SDS)11-30-79. Bethesda: Undersea and Hyperbaric Medical Society; 1979; 82 pages.

Davis JC (ed). The Return to Active Diving After Decompression Sickness or Arteial Gas Embolism.Proceedings of a Symposium held 28 May 1980. UHMS Publication Number 41(CW)11-13-80.Bethesda: Undersea and Hyperbaric Medical Society; 1980; 42 pages. RRR ID: 4245

He was a TRUE pioneer in EVERY since of the word.