Is it cheating?

[alanconstant]

I have read posts regarding flying and diving. I understand the new "standard" for flying after diving. However...

Our instructor has stuck to the 24 hour no fly standard.
Our dive op in Cozumel is also a 24 hour no fly advocate.
I always opt for conservatism.

Here's the situation: we plan to dive 5 days in Cozumel--4 days, a day off, one last 2-tank dive, and fly out the next morning (about 22 hours after our last dive). We plan an evening out after the fourth dive trip (a very special occasion) so I prefer not to dive the following day.

Are we "cheating" by taking a day off and treating the last dive day as non-repetitive?

Would diving Nitrox on the final day make a difference?

Thanks in advance for any advice.

Alan

 

[DocVikingo]

The following assumes typical Coz diving, including observation of recreational standards, e.g., no deco obligations.

You finish the second of your 2 tank AM dives at around noon.

Then you do no diving on the next day.

The following (last) day you do another 2 tank AM dive, with the first dive starting around 9:30. This means a surface interval of about 45 hours, sufficient time that this dive could legitimately be treated as non-repetitive.

However, you indicate plans for a 2 tank dive on this final day. A 2 tanker of course puts you back in the repetitive dive category & a 24 hour wait by the more conservative guidelines.

As far as minimizing N2 load during a dive trip, the more diving of EAN to air tables the better, including the last day.

Have fun.

DocVikingo

 

[pasley]

DISCLAIMER: NOT A DOCTOR OR EXPERT OF ANY KIND.

In additon to the several days of heavy diving and your plans to take a day off, I would also be concerned about your reasons for taking the day off. Sounds like a little consumption of acohol is anticipated that may contribute to dehydradion. So diving the following day in a dehydrated state in addition to the two tanks only increases your risk and the necessity of caution.

 

[fins wake]

.... involving an evening out sounds like a birthday, a wedding anniversary or a proposal ...

Pasley need not worry, it was quite clear from alanconstant's initial post that after the evening out

I prefer not to dive the following day.

Being dehydrated the day after the day off seems very unlikely, there's plenty of (non-diving) time to recuperate and hydrate at leisure. So enjoy the special evening!

DocVikingo is of course right that the 2-tank dive makes the final dive a repetitive one. Personally, I'd be happy - if it were me - with a 22-hour surface interval before flying as you've indicated under the circumstances (no deco obligations, second dive usually shallow in Coz, day off etc). But that's merely how I would do it, not specific advice to you guys.

Using nitrox the final day and diving to air tables (or air computers) will decrease your nitrogen load. Using nitrox for all dives all week will decrease any possible (and potential) nitrogen load even more ... If you have the option of diving nitrogen, are certified to do so and it fits your dive profiles, I'd do it anyway. If it's there, use it.

 

[Dr Deco]

Dear alan:

The advice from the earlier responds sounds fine to me. Do recall that diving nitrox would need to be on an air table or you gain not advantage with respect to reduced gas loads.

Additionally, be careful after the final dive about lifting and other strenuous activities. These cause to formation/growth of microbubbles that hold the gaseous nitrogen for a long duration. Dissolved nitrogen will be rather quickly eliminated, but nitrogen sequestered in bubbles is expelled at a very slow rate. And, it is these small bubbles that grow on the airplane and cause you problems.

I would additionally suspect that heavy, strenuous activities post dive would not be added to the fly-and-dive tests being planned/conducted. As I have mentioned before, tables must be used under the test conditions for them to be valid for your particular situation.

Dr Deco :doctor:

Readers, please note the next class in Decompression Physiology :grad:
http://wrigley.usc.edu/hyperbaric/advdeco.htm