18hr Flight Ban Valid After 5' Dive?

[vladimir]

Actually, aerobic exercise increases the risk of DCS. Take a nap, you'll probably be tired after your pool session.

In general, the caution against post-dive exercise is good advice. The nap recommendation is not. The increased circulation associated with light activity promotes better off-gassing, and a nap might mask DCS symptoms.

http://www.scubaboard.com/forums/ask-dr-decompression/149868-nap-not-nap.html

In the context of a 10 foot dive, of course, none of this matters.

 

[mempilot]

Sure you can get bad advice here. You can also get bad advice at your LDS or from your instructor. Many of the people here *are* those people. Their advice isn't automagically good if delivered in person and bad if delivered online. The difference is that bad advice on SB almost never goes unchallenged.

I agree with you 100%.

There are a lot of gray areas in diving where bad advice can be hidden in the body of good advice. Sadly, those are often the tidbits that set inexperienced divers up for incidents. That being said, many knee jerk react in the opposite direction and give unrealistically conservative advice which, while it won't get someone hurt, it can alter their opinion about the sport they want to pursue.

The perfect example lies in this thread.

Q. Diver asks if he can fly shortly after a pool dive so as to have opportunity to dive in a premium location with dive buddies.

SB Ans A. No. Flying after diving is forbidden.
SB Ans B. Yes. Flying after diving in a pool is acceptable.
SB Ans C. This answer actually has nothing to do with the Q.

Debate ensues about the validity of Ans A as it relates to pool dives and what defines a pool vs a pond. The original diver decides to go with the conservative answer, so he doesn't travel and misses out on the trip when in reality, he could have done it. These quick unthought out answers do influence new divers to either do the wrong thing, or remain sheepish about diving.

This happened to some degree with my GF. I told her to come here and poke around. She asks some questions and got 99 different perspectives, 98 of which were just plain silly. Weeding out the good from the bad is diluted when everyone is willing to dole out advice when they don't know the receiving end. Anonymity has it's advantages to those doing the doling.

So, she finally decided to stick with asking questions of those she knows and trusts. She has progressed quite nicely into a better than standard educated openwater diver able to actually calculate SAC and RMV in order to properly plan her dives using appropriate equipment and procedures. Why? Because she went headlong into extensive education and training, and stayed away from the couch divers and Dr. Phil wannabes.

That doesn't apply to everyone, but the problem for new divers is determining whos advice is sound and whos isn't.

 

[tomboone]

Well OP you did it again. You went and got us all worked up.

Just wait til I actually start diving...lol.

BTW, I called my LDS I'm training through to explain the situation, and they said "All they were allowed to advise me is that it is recommended to wait 18-24 hrs." I tried to press to see if it was different at all for this situation, and they just repeated that line again and again. Oh well...

Thanks for all the help, I'm going to consider myself good to fly about 8 hours after this short, 5-10 foot dive the night before. Thanks all!

 

[mempilot]

Thanks for all the help, I'm going to consider myself good to fly about 8 hours after this short, 5-10 foot dive the night before. Thanks all!

Tom,

The NOAA Ascent to Altitude table gives the following guidelines for exiting the dive as a Pressure Group A: There is no restriction on flying. Coming out as a PG B, you have only a 2 hr 11 min wait for an ascent to 10,000.

Commerical airliners are pressurized to a maximum cabin pressure altitude of 8000 feet. If the plane experiences a catastrophic failure causing rapid depressurization, getting bent will be the least of your worries, mate. And, everyone on board the aircraft will be bent, whether they went diving or not.

So, wait if you want, but coming from someone who looks at this a lot closer than a PADI manual since I fly for a living and dive on my days off with no ill effect for the last decade, I'd go ahead and jump on the earliest flight out.

Now when it's time to return after doing some OW dives, I'd stick to the rules if I were you.

Eric

 

[TSandM]

I think everybody here needs to cool down.

Mempilot, I do read people's posts, and usually fairly carefully, and I came away with the strong impression that you were arguing that there WAS some danger. For example, if you read one of your posts above, you have typos that result in making it completely unclear what you were advocating.

I suspect we may all be saying and thinking roughly the same thing, but not communicating it effectively. Maybe we should all give one another a little benefit of the doubt?

The bottom line is that the OP is safe to fly about as quickly as he can get dried off, dressed, and get himself to the airport. I think we all agree on that.

 

[mempilot]

For example, if you read one of your posts above, you have typos that result in making it completely unclear what you were advocating.

Please point out the typo and I will fix it so as to cause anyone else any confusion.

 

[XXXL]

10 fsw = 1.3 ATA

PN2 @ 10 fsw = .78 * 1.3 = 1.02 ATM

A Slow Tissue Compartment with 40 minute half-life:

HTP1 40 min 50%
HTP2 80 min 75%
HTP3 120 min 87.5%
HTP4 160 min 93.8%
HTP5 200 min 96.9%
HTP6 240 min 98.4%

HTP6 = fully saturated

((Y-X)/2)+X); where X = HTPn half life % and Y = HTPn+1 half life %

My point about living at 5 fsw is summed up above with an example at equivilent maximum depth of the pool in seawater. It would take the diver 240 minutes or 4 hours breathing air to become fully saturated.

I doubt he stayed at 10 feet for 4 hours.

Mempilot,
I am confused over this, as it was not how I was taught. I believed that a 1/2 life was 50%, 75% 87.5% etc.
But my tec instructor says this cant be so & gave me the following as an example

'Halftime' is time to half way.
Take your 20 min compartment.
It starts at 0.79bar because that's what you're breathing on the surface.
The target is 4m depth so 1.4 bar absolute so 1.4*0.79=1.106 bar N2 (assuming you're breathing air).
After the first 20 mins it gets half way (0.79+1.106)/2 = 0.948bar
after another 20 minutes it gets half way over the remaining distance (0.948+1.106)/2 = 1.027

I still agree that it would take a hell of a long time to get saturated at this depth.
I am not disbelieving you, but just need it clarified in my own mind.

 

[DandyDon]

So much for no personal attacks. I couldn't follow their argument...

Just wait til I actually start diving...lol.

BTW, I called my LDS I'm training through to explain the situation, and they said "All they were allowed to advise me is that it is recommended to wait 18-24 hrs." I tried to press to see if it was different at all for this situation, and they just repeated that line again and again. Oh well...

Thanks for all the help, I'm going to consider myself good to fly about 8 hours after this short, 5-10 foot dive the night before. Thanks all!

Yeah, they have to stick with certain rules and regulations to avoid unneeded liability. We don't. True, if you took a hit and couldn't walk for the rest of your life, you couldn't sue us - but there is no risk.

I once planned 2 dives to 20 ft before noon, with an afternoon flight home. I went over the NOAA charts including time to fly with my Tech Inst who was sponsoring the dives and he approved. Yes, it was in a real jet airliner, not a treetop plane.

 

[ishmaelcat]

I think everyone agrees about the OP being able to fly safely. I think the disagreement is about Mempilot's seeming contention that saturation at 5 ft. has similar or the same potential implications as saturation at other depths.

I don't have years of diving or multiple certs to appeal to, but I know some basic physics and biology, and I know that as I sit here in my sea-level apt in Goleta, my blood is saturated with N2 and will not ongas any more at this "depth." If I now travel to the top of a 12,000 foot mtn, the pressure will be about .69 atm. My blood will begin to offgas. I think this gradient is fairly close to the saturated diver at 5 ft flying to 8,000. It's certainly well less than the 5-footer (at, as we've heard, 1.12 atm), flying to 5,000 ft, which is at .83 atm (74% or so of 1.09).

People don't typically worry about getting the bends from traveling between the beach and the snowcaps, even if they don't know lots of decomp theory.

I'm not sure why everyone gets so worked up though.

 

[DandyDon]

I think everyone agrees about the OP being able to fly safely. I think the disagreement is about Mempilot's seeming contention that saturation at 5 ft. has similar or the same potential implications as saturation at other depths.

I don't have years of diving or multiple certs to appeal to, but I know some basic physics and biology, and I know that as I sit here in my sea-level apt in Goleta, my blood is saturated with N2 and will not ongas any more at this "depth." If I now travel to the top of a 12,000 foot mtn, the pressure will be about .69 atm. My blood will begin to offgas. I think this gradient is fairly close to the saturated diver at 5 ft flying to 8,000. It's certainly well less than the 5-footer (at, as we've heard, 1.12 atm), flying to 5,000 ft, which is at .83 atm (74% or so of 1.09).

People don't typically worry about getting the bends from traveling between the beach and the snowcaps, even if they don't know lots of decomp theory.

I'm not sure why everyone gets so worked up though.

Good one!