Skydiving After Scuba?

[benbrockwell 0]

Hey everyone,

My friend and I are headed down to Florida to jump and we wanted to get some diving in, too. We plan to jump the day after we dive.

We'd do two dives to the no dec limit on regular air. The diving would end by 2 and we'd be jumping no earlier than 9 the next morning, giving us a no-fly interval of at least 19 hours.

So... How safe is this?

Thanks,
ben

[porpoishead 5]

hey bud wassup?

you should be fine after 12hrs if you stick to your no D limit which in scoobydoo if I remmember correctly leaves you at your first "O" group designation, you'll be clean after 12hrs. now if you get to "O" designation twice within 24hrs then you should wait 24hrs to get to altitude.

be smart, be safe, remember that your bottom time does not stop until your final ascent factor in your water stop, be conservative, if youre in current and overexerting yourself then go up to the next table. mother ocean shows no mercy...

on second thought bro be safe and wait 24hrs a cns hit is some serious shit, you wont be skydiving, diving, or anything much really, youll have your hands full learning to walk again, or maybe even breathe, be safe brosef...

if you want a friend feed any animal
Perry Farrell

[kkeenan 13]

Much less hassle if you can arrange to do the diving after the jumping.

Kevin

_____________________________________
Dude, you are so awesome...
Can I be on your ash jump ?

[porpoishead 5]

absolutely, best to err on the side of safety. DCS can really complicate your life.

if you want a friend feed any animal
Perry Farrell

[Martini 0]

[url]www.diversalertnetwork.org/medical/articles/article.asp?articleid=20

I believe that the reccommendation for flying in commercial aircraft which are typically pressurized to 8000' msl is a 12 hour wait after the last no-deco dive. How you relate this to skydiving at 13000' is up to you. How long, how deep, how many dives, your risk tolerance, alcohol/drug consumption, physical condition etc. A lot of stuff to manage. 24 hrs is considered a good delay time, 19 hours might be ok too. Or not. I've made many jumps fairly soon after diving but manage the risk by managing my dives and jumps. But some think I'm using myself as a Guinea pig too. What works for me might kill you. There are no fixed rules here.

Sometimes you eat the bear..............

[porpoishead 5]

very good point. I myself have ommited deco, and violated no fly times in the past, without incident. on the other hand I have seen so many get bent for no reason what so ever. as you stated many many factors, proper hydration before/after,hot shower, etc ...

if you want a friend feed any animal
Perry Farrell

[kelpdiver 2]

The no fly guidelines have been a bit of a joke, esp in how the resort industry lobbied, not with science, but with economics, to shift the general guideline back to 12 hours.

In truth, you can usually get away with the more aggressive approaches. Some of my DIR friends get on the plane with their hair still wet. They are better than the norm on deco tables, ascent rates, and fitness. The "optional" safety stops and 30fpm ascent rates remove a lot of those nitrogen bubbles.

But flying in an airliner is nothing like flying in an open cabin to 13k. If a flight from Cozumel to Houston lost cabin pressure, you'd see a lot of DCS cases.

The only other thought - if you're going to push it, it's better to go deep to the tables limits than shallower to the limits. Fast in, fast out.

[Johnsisland 0]

Quote

Hey everyone,

My friend and I are headed down to Florida to jump and we wanted to get some diving in, too. We plan to jump the day after we dive.

We'd do two dives to the no dec limit on regular air. The diving would end by 2 and we'd be jumping no earlier than 9 the next morning, giving us a no-fly interval of at least 19 hours.

So... How safe is this?

Thanks,
ben

Ben,

I think it would be much safer and easier if you switched the dive/jump to jump/dive.

Sometimes people are bent when the dive profile was conservative, sometimes you may never know why.

Do you know if you have Patent Foramen Oval? A percentage of people have PFO, and have increased risk of being bent on a conservative dive profile.

I am risk averse, and seek to minimize risks. Perhaps the dive/jump situation is within your comfort zone for risk.

Does your insurance cover a helicopter ride? Chamber dive? Rehab? Are there any restrictions on coverage?

Again, is it possible to jump/dive?

J

[Travman 6]

A co-worker did an advanced divers course over several days. There were 15 others on the course. When the course was over they all drove back from the coast, a trip of about 2 hours and an elevation of about 2500 ft.
Shortly after he arrived home he went into a deco chamber for 7 hours. No one else was affected.
Deco can be a funny thing. Personally I usually jump saturday and dive sunday.

[jraf 0]

Porpoishead has the gist in his post. I would definitely recommend 24 hours if you intend on going any deeper than 30 feet.

jraf

Me Jungleman! Me have large Babalui.
Muff #3275

[benbrockwell 0]

Hey everyone,

Thanks so much for all of your replies. They've all been incredibly helpful.

Given the uncertainty of the whole thing, we'll probably extend the no-fly time another day, or dive only after the week's jumping is over. Also, we might dive Nitrox on the air tables, to further increase our margin of safety.

On a side note, I was interested in the comment about diver-heavy flights, like those from Cozumel-Houston, and how they are full of Nitrogen-rich people. It got me thinking: What if airlines were to offer flights from popular dive destinations with the cabin pressurized to sea level, and not the usual 8,000 feet? Divers would no doubt be attracted to this for safety reasons. But are there any disadvantages associated with doing this? Threats to the airframe's integrity? Increased cost?

Thanks again, everyone.
ben

[jumpdr 0]

I think cost would be the main thing. You'd have to have a fairly well sealed aircraft to be able to maintain sea level pressures. Not sure it'd be worth the extra ticket cost the airline would have to charge, compared with a day of not diving before you left.

Skydiving is more than a sport and more than a job: skydiving is pure passion and desire which will fill a lifetime.

[willard 0]

The cabin of the aircraft could be safely pressurized to sea level, however this would require the flight to be flown at a lower altitude than normal thereby decreasing cruise speed and efficiency. The problem isn't the pressure inside the cabin, but in the pressure differential between cabin and the surrounding environment.
Don't know much about diving, though. I swim like a brick full of holes!

[ZigZagMarquis 8]

I don't SCUBA, so I don't know anything about "dive charts", "dive computers", how long after SCUBA diving before you can go back up and all that... but the "rule of thumb" I remember from FJC and JM training is you can Skydive & then SCUBA, but not the other way around... i.e., you can go up (ride up in a jump plane), skydive and then keep going down, SCUBA, but not the other way around, you CANNOT go down (SCUBA) and then back up (SKYDIVE)... without a sufficient break in between, but, again, I don't know how long that is or how to figure it... so, sounds like you'd be better off Skydiving on the first day and then SCUBA on the next... but why would someone want to jump out of a perfectly good boat??

[VincentVL. 0]

I have a dumb question: If commercial plains are pressurised, then how come you still have to clear your ears lest you get earpain?

[ZigZagMarquis 8]

Yes, commercial aircraft are pressurized, but some are better then others... as in, they don't all perfectly keep the cabin pressure the same as "sea level"... I think they have to maintain the cabin pressure to at least "like" 8K MSL... as in the cabin pressure cannot get any "higher" then that, but I'd expect varriations in cabin pressure in-between sea level and 8K... ergo, your ears pop.

[squirrel 0]

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I have a dumb question: If commercial plains are pressurised, then how come you still have to clear your ears lest you get earpain?

next time you fly, where your altimiter...your question will be answered when your at 28k but your altimiter reads 6 or 7k feet.

________________________________
Where is Darwin when you need him?

[willard 0]

"... but why would someone want to jump out of a perfectly good boat?? "

Gotta love it!

[kelpdiver 2]

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On a side note, I was interested in the comment about diver-heavy flights, like those from Cozumel-Houston, and how they are full of Nitrogen-rich people. It got me thinking: What if airlines were to offer flights from popular dive destinations with the cabin pressurized to sea level, and not the usual 8,000 feet? Divers would no doubt be attracted to this for safety reasons. But are there any disadvantages associated with doing this? Threats to the airframe's integrity? Increased cost?

loss of pressurization becomes an even bigger risk. Cost matters aside, non divers might get bent in such an event.

Deco theory started with the notion that bubbles form when pressure drops in half. From sea level pressure, that's at about 18k. I don't know that having the cabin at 5-8k buys you quite enough to get to 30some thousand, but it's closer.

Dollars are likely the leading reason.

[Zing 2]

I've flown on the decompression express a number of times out of Cozumel, and seen two people unloaded in Houston with symptoms of decompression sickness. The one guy ... fortyish? ... happened to be sitting in the same row as me. Said he'd waited 24 hours between last dive and the airline flight. He was complaining of deep tissue pain in his arm, shoulders and neck and had an impressive display of small "skin bubbles" on his upper arm and shoulder. The other case was a younger man, but I don't really know any details about him other than he was given oxygen and they had medics waiting for the plane when it landed.
I've pushed the limits for diving and flying a few times, so far with no ill effects that showed, so far. I'm now in my mid-fifties and try to be more conservative.
I had an interesting conversation with a medical person with a bit of expertise in blood-gas work. According to him, getting bent "a little" happens to a lot of people who either feel no symptoms, or don't recognize them for what they are. He warned that the effects of getting bent are cumulative. A bit of damage might not bother you in your 20s, 30s, 40s, even 50s, but could contribute to the detrimental effects of osteoporosis, arthritis and other conditions of the skeletal-muscular and circulatory systems. In other words, play now ... pay later.

Zing Lurks

[kelpdiver 2]

Quote

I had an interesting conversation with a medical person with a bit of expertise in blood-gas work. According to him, getting bent "a little" happens to a lot of people who either feel no symptoms, or don't recognize them for what they are. He warned that the effects of getting bent are cumulative. A bit of damage might not bother you in your 20s, 30s, 40s, even 50s, but could contribute to the detrimental effects of osteoporosis, arthritis and other conditions of the skeletal-muscular and circulatory systems. In other words, play now ... pay later.

Yes - each hit you take makes you more succeptable to future hits. Preclinical DCS can certainly accumulate. Type II hits (central nervous system - type I is joints) are especially bad in that you may never fully recover, and a repeat could be really bad.

The challenge, of course, is how to identify such cases. If I go diving in the Channel Islands (LA) for a weekend, I'm aching a bit the days after. Lugging over a hundred pounds of gear into the car, onto the boat, and back out again, along with a dozen donnings and doffings of 80-90lbs of gear in cold water is hard work and going to strain the muscles a little bit.

[bigdad510 1]

Everytime I teach a SCUBA class I get asked about flying and diving. It seems the rules change each year, but its always been at least 12 hours between diving, I think this year its 18. The conservative answer is 24hrs and even then, you can have microbubbles still in your system.

The dive charts,tables and computers are used as a "measure", everyone is different. I know divers that have been bent by doing a 60 foot dive, well within the limits of PADI table, but still suffered.

I agree with the post of switch the two. Skudive them SCUBA. Even small elevation changes can effect some people and a pressurized cabin in an aircraft for 8k can have ahuge effect on some. Some people can off-gas quicker than others.

For skydivers after SCUBA diving, not a good idea. The rapid accent to altitude causes the body to release Nitrogen at an extrememly fast rate, and even microbubbles still in you system can cause DCS.

Brad

[Martini 0]

Not to argue your points, clearly added decompression after diving is an added risk. But time at altitude is a factor. Riding in a commercial aircraft, even pressuruzed to 8000' msl, is a prolonged event. Riding a jump plane to 13k might be 20 minutes.

BTW at 13k atmospheric pressure is around 1/8th atm. That is a pretty significant drop.

Again lots of stuff to factor. My take has been to do a single dive to no more than 60' for an hour or so (most of my dives are deeper, longer and get into deco) followed by about a three hour delay before jumping.and keeping my jumps below 8k (shorter altitude exposure and a relatively low altitude). Of the many times I have done this I have had absolutely no apparent negative effect. I certainly don't reccomend that anyone follow my unconservative methods. Once again I have to state that doing this might prove fatal to someone else. Also I led up to doing this gradually, don't do it often and am aware that there could be hidden consequences. I'm mentioning this to illustrate the point that there aren't absolutes here and you aren't bound by all the naysaying advice. It is all very consertaive and that is as it should be. Very few studies have been done regarding flying after diving, none have been done about skydiving after diving. Learn what you can, make informed decisions and decide what level of risk you can accept. No you don't have to jump after diving but you might want to. No one will tell you that it's ok but that doesn't mean that it isn't.

Sometimes you eat the bear..............

[kelpdiver 2]

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Not to argue your points, clearly added decompression after diving is an added risk. But time at altitude is a factor. Riding in a commercial aircraft, even pressuruzed to 8000' msl, is a prolonged event. Riding a jump plane to 13k might be 20 minutes.

BTW at 13k atmospheric pressure is around 1/8th atm. That is a pretty significant drop.

Err, no, it's .563 atms at 15,000. You would die if it were only a PPO2 of .03. Even the summit of Everest is about 1/3 atm.

And I don't agree with the time element either. The bubble formation starts up immediately. The steeper gradiant of 13k promotes that. A long time at airline pressure (I find it typically a bit lower than 8k) promotes the off gassing, so long as it's under the threshold for bubbles the duration isn't a threat.

[willard 0]

The pressure at 13k is much more than 1/8 atmosphere. One would need to climb to app. 47k to get that kind of drop. The press at 13k msl (standard day) is closer to 9 psi, or roughly 3/5 sea level.