Qs About Science of Diving Content

[tursiops]

Were you an instructor and involved in the debate back then?

Irrelevant. It has all been reported and published; when I get home in a few hours I'll provide the reference.

 

[BoltSnap]

Irrelevant. It has all been reported and published; when I get home in a few hours I'll provide the reference.

Were you? Can you explain why DAN Europe said otherwise? Can you explain why SSI, NAUI still say 24 hours?

 

[tursiops]

Irrelevant. It has all been reported and published; when I get home in a few hours I'll provide the reference.

See Flying After Diving
and attached.

 

[Beau Holden]

I remember looking at my computer profile after diving the Car Wash cave in Tulum. It was one of the worst sawtooth profiles you will see

If I remember correctly Mayan Blue is the same. That was my first fun dive after full cave certification and we were doing this as a planned deco dive. I remember in and out of the halocline was driving my buoyancy nuts. But it is a beautiful cave and would like to do it again.

 

[Beau Holden]

As long as you are diving within limits, the difference should not matter.

I have heard all the recommendations and course guidance about not doing saw tooth dives. At what point does it actually become one. Is it a change in +/-3-ft, 5-ft, 20-ft, 30-ft? How is that actually defined? Ever had to chase students? How about a group of say 5 students and the instructor doing the CESA skill? There is a lot said that seems to conflict with actual diving (training), in my opinion.

Reverse profiles, yep don't do them as them as the rule makers say but if you are within gas limits, ascent rates and NDLs or deco requirements, where is the evidence that this will hurt or kill you. If my computer cannot account or track that, then I need to go back to tables. I can plan a reverse profile on a table? Does that make the table wrong?

Don't get me wrong. I do dive conservatively base on the training and information I have at hang. Not to say stupid has not ever came to visit. Never been bent and pray God I never do get bent. However, it has always been a pain in my ass for someone to tell me not to do something and not give a good defenitive reason why.

 

[boulderjohn]

I remember in and out of the halocline was driving my buoyancy nuts. But it is a beautiful cave and would like to do it again.

Since most readers have never experienced this,I will add that when you ascend or descend through a halocline, the normal process used to maintain buoyancy is reversed.

 

[Beau Holden]

when you ascend or descend through a halocline, the normal process used to maintain buoyancy is reversed.

True. Also on this dive, my HP hose was across the top corner of my wing and I was not venting completely when through the bottom dump, which I normally use during the dive so I was really wacky. Another lesson learned about rechecking hose position before splashing.

 

[Dan G]

whenever this topic comes up i always wonder why so many people get so wrapped up in what i would consider to be such a minor detail.

is someones holiday time planned that tight that they cannot manage to wait 24 hrs? will their vacation be ruined over a measly 6hrs?

pls remember that the DAN recommendations are "minimum" times required. people seem to over look that.

i don't know about you but i try to exceed minimum standards with most things in life and i have very rarely been diving where i pushed my limits. when it did happen it was due to my own poor execution of the dive plan. it was not because i planned it that way.

if the max i can dive today is 100 feet, i don't dive to 100 feet. if my max time at a depth is 60 min, i don't stay down 60 min. but thats me. many others will disagree.

so when we dive on holiday, we plan our time so we have at least 24hrs before we fly. its not that hard. why not be conservative. there are other things on holiday we like to enjoy.

if you did one dive on a trip that was no where near your limits, would it be safe to only wait 12hrs? if you did 5 days of 2 dives per day, would it be safe to only wait 18hrs? i would respectfully say the answer is somewhere between maybe and probably.

are you in peak physical condition? did you consume large amounts of booze that week? are you dehydrated most of the time? was your last dive on the verge of requiring an added deco stop? etc etc there are so many variables.

if many divers choose to follow the 18hr rule and nothing bad ever happens, then thats great. but that does not mean it is a guarrantee all divers will have the same results. i choose to wait the 24hrs.

Not to pick a fight over this, but the SSI recommendation of 24 hrs is also a minimum standard. Here is the language from the Science of Diving manual:

SSI’s recommendations are:

1. A minimum surface interval of 24 hours is required to be reasonably assured a diver will remain symptom free upon ascent to altitude in a commercial jet airliner (pressurized to an altitude of 2500m).
2. A surface interval of more than 24 hours is recommended after daily, multiple dives over several days or dives that require decompression stops. The greater the surface interval before flight the less likely decompression sickness will occur.

I would guess that virtually all divers who go away on a dive trip fall into category #2. That means, 24 hours is not even the minimum standard for most vacation divers.

I think it is an argument of semantics to state that "I do more than the minimum." Where does it end? For example, the minimum standard is to carry a primary second stage and a backup second stage. Why not carry a third or even a fourth second stage and therefore exceed the minimum?

 

[boulderjohn]

SSI’s recommendations are:

1. A minimum surface interval of 24 hours is required to be reasonably assured

The old English teacher in me struggles to understand that.

Since there is no enforcement of the this, the word required cannot mean anything akin to the phrase "required by law." It is more likely a synonym for needed, as in "A standard bechamel sauce requires the blending of equal parts flour and melted butter." They further diminish the impact of the word required by labeling it as a recommendation. Finally, they diminish it further by saying that if you follow the required recommendation, you can be reasonably assured....

So, I need to ask. You said, "Not to pick a fight over this, but the SSI recommendation of 24 hrs is also a minimum standard." How can a recommendation be a standard?

 

[DeepSeaExplorer]

The wording is an attempted hedge. If anyone tries to sue, be reasonably assured that within 24 hours, they’re going to hide behind the word recommendation.