Flying After Diving

[PK1]

I volunteer at my local aquarium. I regularly dive the exhibits for cleaning and feeding. Depths range from 8-15 ft. Air supply is via hookah hose to compressor. Average dive time is 45 minutes. Can someone please advise whether usual flying after diving guidelines apply to these types of dives. I’m scheduled to work at the aquarium on Friday and then am flying on Saturday.

 

[boulderjohn]

Here are some facts that may help you make a decision.

• You are essentially doing a 45 minute safety stop.
• On the U.S. Navy tables, you would finish the dive as an A or B diver--barely.
• Scottsdale's elevation is 2,165 feet, so a flight would be an elevation gain of about 6,000 feet to a pressurized cabin.
• On the U.S. Navy ascent to altitude table, a diver in groups A, B, C, and D can ascend 6,000 feet without any surface interval. A diver in pressure group E would have to wait 51 minutes. It might take more than that to get from the Aquarium to takeoff time.

 

[chrisch]

This topic has been discussed a lot on here and you will find a lot of opinions and points of view, I agree with John - this is not deep enough and long enough to worry about.

You will find other views.

 

[Ballyhoo]

If you have a dive watch computer I would be interested to see if it gives you the no fly signal after your dive that shallow.

 

[CT Sean]

If you have a dive watch computer I would be interested to see if it gives you the no fly signal after your dive that shallow.

It depends on the computer but I'll bet most give you a simple 24 hour countdown based on what the PC considers a dive ending. My wife's Oceanic will display a 24 hour countdown upon surfacing and it'll log almost anything more than a couple feet deep as a dive. Mares newest top of the line "Quad Ci" says it will only give you a 12 or 24 hour countdown depending on single or multiple dives. I doubt there are any that will do any time to fly calculations based on dive depth and time.

 

[gamon]

You're good.

Safe travels.

 

[kdlv]

It depends on the computer but I'll bet most give you a simple 24 hour countdown based on what the PC considers a dive ending…

Garmins have the option to calculate depending on dive profiles not only taking into account the last one.

Ontopic: curious about using hookah. The supplied air density should be at surface level. Meaning that underwater at 5-6m (15ft) you are breathing less volume of nitrogen and oxygen as opposed to if you were breathing compressed air from a tank that is at your depth. Therefore the amount of nitrogen in your tissues should be significantly lower and wouldn’t present an issue at all. Indeed in my lame point of view this appears to be a long safety stop with no effect on no fly time. What am I missing?

 

[LFMarm]

Algorithm in DCs typically doesn’t use Navy tables but much rougher guidelines. The answer from John is spot on.

 

[inquis]

What am I missing?

The fact the supplied air cannot be at 1 atm, since the water pressure would prevent you from taking a breath. At 15 ft, it would be an additional ~7 lbs per square inch, and there are quite a few of those on a torso.

 

[kdlv]

That I understand. With hookah you will get the 125-135 psi at the 2nd stage. The theoretical question is whether at 5m/15ft you still breathe 21% oxygen and 78% nitrogen or you get 31% oxygen and 117% nitrogen (very rough calculations) during every breath as the air in the hose is subject to pressure at depth before reaching the 2nd stage.