Flying after diving...

[RDRINK25]

So if I where to skip a dive. Is it a more conservative profile only doing 2 dives on Sun to 100' and 2 dives on Mon with one being 75' and one being 60'? Or getting an extra hr of SI on the second day by doing 3 dives the first day and 1 the 2nd? I could alway only do 2 dives the first and 1 the second?

---------- Post added May 19th, 2015 at 10:36 PM ----------

I do have a Liquidvision Lynx which gives me my saturation and my max elevation

 

[RDRINK25]

 

[Steve_C]

3 dives the first day and 1 the 2nd?

It is not an extra hour of SI. It is reduced extra loading on the second day from one dive rather than 2.

 

[RDRINK25]

It is not an extra hour of SI. It is reduced extra loading on the second day from one dive rather than 2.

Im good with dropping the second dive on the 2nd day.

 

[RJP]

---------- Post added May 19th, 2015 at 10:36 PM ----------

I do have a Liquidvision Lynx which gives me my saturation and my max elevation

It does not give you YOUR saturation. It shows you a predicted saturation based on whatever model.

There's a difference.

 

[Charlie59]

I am not sure how a bubble study that does not correlate with clinical DCS should cause too much anxiety. I suspect people have some sub-clinical DCS in the middle of their week of diving based on bubble studies with no clear complications. If there was some evidence of clinically relevant DCS occuring in spite of following current DAN recommendations for flying after diving I would worry. Since there is no such information available, I think you should feel comfortable doing what you have always done. If or when DAN changes their recommendations, then I think you should change your approach, but not at this time based on one small study.

But just as with everything in diving, you are responsible for yourself.

 

[geoff w]

Personally, I'm conservative and always plan for 24 hours for offgassing with repetitive dives, even when diving nitrox (all recreational, non-deco dives)

If you want to really confuse matters and get your head spinning, look at the Navy Dive Manual, which will help you figure out how long to wait before flying after diving, depending on your ending pressure group (that would be the Navy pressure group scheme, not PADI or others). The manual is available for free online. Of course, it's also based on young, fit Navy divers and not necessarily the typical recreational diver, so YMMV

 

[Scuba7]

The tables are ultra conservative so it really comes down to your level of fitness.
If you are overweight, old, etc, 19 hours might not be enough time.

You can make it safer by cutting out the alcohol, cigs, stress, after the diving.

 

[MB]

Many of the recs here suggest additional safety factors for which you cannot go wrong: skip the drinks, stay hydrated, get extra sleep (as if we even had a choice!), etc. Nice!

But it is worth an extra note of caution... It is common advice that the last dive before boarding a plane should be a shallow dive. Well... maybe... Many divers figure that because the last dive is shallow they will stretch is out. Bad idea. The shallow vs deep decision is about maximizing tissue loads, but most divers make this recommendation without discussion the TYPES of tissues that are being loaded. In general, deep dives load fast tissues; shallow dives tend to load slow tissues. Fast to load also means relatively fast to UNload. And slow to load also means slow to UNload. Frankly, if the computer allows, I'm more likely to hit a shorter deeper dive for the last one than to max out the shallow dive. Just because you dive to 30' for a gazillion minutes does not mean you will off gas faster than a deeper dive under the NDLs!

So if you are planning to dive shallow for the last dive, keep it short. And use 40%. And stay hydrated. And skip the tennis and hot tub after. And don't smoke. Did I mention staying hydrated? And don't forget the map. Oh, and BTW, go ahead and enjoy the 24+ hours before the flight! Who needs to hassle those nice folks at DAN???

 

[EFX]

But it is worth an extra note of caution... It is common advice that the last dive before boarding a plane should be a shallow dive. Well... maybe... Many divers figure that because the last dive is shallow they will stretch is out. Bad idea. The shallow vs deep decision is about maximizing tissue loads, but most divers make this recommendation without discussion the TYPES of tissues that are being loaded. In general, deep dives load fast tissues; shallow dives tend to load slow tissues. Fast to load also means relatively fast to UNload. And slow to load also means slow to UNload. Frankly, if the computer allows, I'm more likely to hit a shorter deeper dive for the last one than to max out the shallow dive. Just because you dive to 30' for a gazillion minutes does not mean you will off gas faster than a deeper dive under the NDLs!

Using my spreadsheet and plugging in the numbers for a 30 ft 120 minute dive and a 80 ft. 5 minute dive the difference in tissue compartment (TC) loading was insignificant. After a SI of 18 hours all TC's were the same except for TC's 11-16 using the DSAT table. Here are the numbers (pressure absolute in feet of sea water):

Depth: TC's 1 - 16
30: 24.4, 24.4, 24.4, 24.4, 24.4, 24.4, 24.4, 24.4, 24.4, 24.4, 24.6, 24.7, 25.0, 25.2, 25.2, 25.3
80: 24.4, 24.4, 24.4, 24.4, 24.4, 24.4, 24.4, 24.4, 24.4, 24.4, 24.5, 24.5, 24.6, 24.7, 24.7, 24.8

As a point of reference the surface pressure for N2 is 24.4 fsw.