Question...kinda urgent (not a medical issue)

[ScubaSixString]

I'm planning on a dive tomorrow to arounf 70 ft on air. Possibly 2 dives. Assuming i stay withiin NDLs, how stringent are the time to fly rules (the 24 hour thing)?

I've seen times using deco software (assuming that profile with deep stops) of as low as 7.5 hours. I have to fly out sunday at 2 pm. Can i surface from my last dive at 5 pm or is the 24 hour a hard rule?


Thanks and i'm sorry if this is in the wrong place

 

[Tassie_Rohan]

From a conference a few years back I understand 18 hours is now the accepted no-flight time. More if doing deco.

You have 21 hours between your last dive and flying, so you will be OK.

Some computers will show less than 18 hours for no fly after shallow dives, however I'm not sure what algorithms they are using to calculate the no-fly time (anyone help here?). I tend to stick to 18 hours.

Cheers,
Rohan.

 

[ScubaSixString]

From a conference a few years back I understand 18 hours is now the accepted no-flight time. More if doing deco.

You have 21 hours between your last dive and flying, so you will be OK.

Some computers will show less than 18 hours for no fly after shallow dives, however I'm not sure what algorithms they are using to calculate the no-fly time (anyone help here?). I tend to stick to 18 hours.

Cheers,
Rohan.

Excellent. Thanks. 24 seemed like alot (especially with a blanket statement) 7.5 seemed almost like asking to get bent...

 

[Tassie_Rohan]

Yep – 18 hours means you can surface from your last dive at 4 pm and be on a plane 10 am following morning. Many people take the 24 hour no fly to mean that they should have a no diving day between there last dive and flying out: this can add up to 38-42 hours which, in my mind, is a waste of precious holiday dive time.

I wouldn't go under 18 hours no fly though - its the minimum amount of no fly for NDL dives, under which cases of DCS have been reported.

Cheers,
Rohan.

 

[MB]

...You have 21 hours between your last dive and flying, so you will be OK...

That's a bit of a broad statement. Some guiidelines do indeed suggest an 18 hr SIT, but I'd be very cautious about categorically stating "You'll be ok." Profiles, repetitive dives, edging up to (or over) NDLs, a diver's hydration, length of the flight and a whole host of other factors affect DCS risk. 18 hours may indeed be a reasonable time period but even a 24 hour wait does not assure a DCS-free flight. Be cautious and attend to the known risk factors, including those listed above.

 

[Tassie_Rohan]

That's a bit of a broad statement. Some guiidelines do indeed suggest an 18 hr SIT, but I'd be very cautious about categorically stating "You'll be ok." Profiles, repetitive dives, edging up to (or over) NDLs, a diver's hydration, length of the flight and a whole host of other factors affect DCS risk. 18 hours may indeed be a reasonable time period but even a 24 hour wait does not assure a DCS-free flight. Be cautious and attend to the known risk factors, including those listed above.

I agree - my statement was a little bit too broad. There are a lot of factors involved but for 1-2 NDL dives with no contributing factors have there ever been any reported cases of DCS after 18 hours? Let alone 21 hours?


Scubasixstring: let me change my statement to:

The weight of evidence is that you will probably live.

Enjoy your flight!

Cheers,
Rohan.

 

[ScubaSixString]

i appreciate all the info....Obviously people get bent diving the NDLs but I think i'll be fine....if i go....i may have a leak around my first stage Checking pressure a few minutes ago and heard a hiss that didn't stop once the hoses were charged.... filling up the tub now *crosses fingers*

 

[Snowbear]

A few things that can make for a lower risk of DCS from flying after diving....

- Keep your profiles conservative.... i.e. don't "push" the limits
- Make your ascents sloooowwww. You will offgas better, faster and more effectively if you ascend slowly and spend plenty of time shallow (less than 2 atm/33') than you will by doing a 30fpm ascent and a 3 or 5 minute safety stop. You are counting on finishing your offgas on the surface
- Stay hydrated before and after diving and stay away from alcohol

I'm sure there are more, but I'll let someone else chime in on them

 

[ScubaSixString]

A few things that can make for a lower risk of DCS from flying after diving....

- Keep your profiles conservative.... i.e. don't "push" the limits
- Make your ascents sloooowwww. You will offgas better, faster and more effectively if you ascend slowly and spend plenty of time shallow (less than 2 atm/33') than you will by doing a 30fpm ascent and a 3 or 5 minute safety stop. You are counting on finishing your offgas on the surface
- Stay hydrated before and after diving and stay away from alcohol

I'm sure there are more, but I'll let someone else chime in on them

I had planned on deep/pyle stops. The only time my computer hasn't screamed "SLOW" at me was when i did them...

But....its confirmed. I have bubbles (small ones but constant and fast) coming out of my SPG hose up near the first stage. Plus a slow leak around the tank o-ring.

dammit. Gotta take it to the lds. On travel for a week then leaving friday for some charter diving in NC. Gonna have to take it in tomorrow and hope they can fix it before friday...

Thanks guys/gals. Sorry for the false alarm...but your advice is helpful. I fly alot

 

[Snowbear]

I had planned on deep/pyle stops. The only time my computer hasn't screamed "SLOW" at me was when i did them...

:11: Yep... I'll say again that you should do sloooowwww ascents. Especially if you are going to push the "fly after dive" limits! By slow, I mean no faster than 10' per minute. And again, plenty of time spent shallow for time spent deep.

I But....its confirmed. I have bubbles (small ones but constant and fast) coming out of my SPG hose up near the first stage. Plus a slow leak around the tank o-ring.

dammit. Gotta take it to the lds. On travel for a week then leaving friday for some charter diving in NC. Gonna have to take it in tomorrow and hope they can fix it before friday...

Replacing a hose and an O-ring should be a "while you wait" service. If they can't do it when you take it in tomorrow I would find a different shop (well, actually, I would do it myself, but that's not for everyone )