Surface time 1 hour because of Microbubbles

[coldsmoke]

There is such a thing as in water decompression but it's really less preferable than a chamber. In the event where no chamber is available quickly enough then in water decompression might be your only alternative, however it should not be done without close supervision by someone who knows a heck of a lot more about it than I do.

TSandM really said it right. You are concerned with the bubbles compressing so much that the are allowed to pass through the lungs without being expelled. A deep dive followed by a quick bounce dive to something even as shallow as 60 feet could cause problems. However a deep dive followed by another deep dive followed by a proper ascent will likely leave you feeling just fine.

There is a school of thought out there that every dive is really a deco dive and that your ascent should allow you to significantly off gas prior to surfacing. Said another way, decompressing in the water is preferable to decompressing on the surface during a SI. (not to be confused with in water recompression when a diver is attempting to treat an incident of DCS)

Hunter

 

[shark_tamer]

What I do after a +30 meters non-deco dive :

- First on ascent, I do micro bubbles stops: Stop for 1 minute at every half distance !
Example: Dive depth was 40 meters. First stop at 1/2 that depth ( 20 meters )for 1 minute.
Second stop, 1/2 that depth ( 10 meters ) for another minute, and then do the satefy stop - 3 minutes at 5 meters.

- Surface interval of minimum 1 hour. That gives me plenty of time to relax and drink lots of water.

 

[Scared Silly]

There is a school of thought out there that every dive is really a deco dive and that your ascent should allow you to significantly off gas prior to surfacing. Said another way, decompressing in the water is preferable to decompressing on the surface during a SI. (not to be confused with in water recompression when a diver is attempting to treat an incident of DCS)

I would not say there is a school of thought - every dive is a decompression dive. No ifs, ands, or buts. The difference is that some require a stop whereas others are no stop. Otherwise what you are saying it ture. I would rather spend 10 minutes at 15 feet looking a some fishes rather than 60 minutes on the surface waiting to see some fish.

 

[coldsmoke]

Well, some agencies teach NDL (No Deco Limits) and others teach MDL (Minimum Deco Limits). And while I think we are in perfect agreement, I think most people are taught that when they are doing recreational dives they are doing no-deco dives. Deco is always required it's just a matter of where you want to do it.

Hunter

 

[Scared Silly]

You are absolutely correct. Some agencies tend to hide this little fact.

BTW you guys getting any smoke? Frickin dry here - and I ain't talking about liquor.

 

[coldsmoke]

No - you guys got fires or something? We're getting snow.

Hunter

 

[dougchartier]

just reading a book about deep diving, deco diving.
They recommend to make surface interval between 2 dives of at least 1 hour.

Reason: at 40-50 min there is the maximum amount of microbubbles.

I don't understand that. I understand that you need a longer surface interval so that the Nitrogen can also leave that parts which react slower.
But what does it has to do with the micro bubbles. Before I though if there are microbubbles and I go down they will be re compressed, disappear. Is that wrong?

I've seen the term "microbubbles" referenced in several posts. Can someone tell me what microbubbles are and how they relate to decompression? Thanks!

 

[bleeb]

I've seen the term "microbubbles" referenced in several posts. Can someone tell me what microbubbles are and how they relate to decompression? Thanks!

Maybe someone else more knowledgeable can elaborate, but in a nutshell: bubbles are believed to have a minimum size. Smaller than that, the surface tension of water exerts more force than the interior gas pressure, and the thing is thought to shrink out of existance, driving all the gas back into solution in the surrounding liquid (the Laplace limit, I think). IIRC, at the surface, this happens somewhere between 1 and 10 micrometers. The value is probably more exact, but right now, my memory isn't.

Since big DCS bubbles start life as small bubbles, minimizing the latter seems like a good idea. I seem to recall that high-resolution ultrasound studies have found that almost every useful recreational dive produces some bubbles. (Maybe not 3 minutes to 5 feet, but I vaguely remember reading something about pool OW training dives.) There is a theory in hyperbaric medicine that these microbubbles may be responsible for 'sub-clinical' symptoms, i.e. irritating things like being tired after a dive, as opposed to 'clinical' symptoms, like pain or tingling, which are known to represent definite medical problems.

Some decompression models (the algorithms used to generate tables or run dive computers) such as RGBM (Reduced Gradient Bubble Model) try to take into account some aspects of diving that affect the formation and suppression of microbubbles.

 

[boulderjohn]

Very new diver here.

There was a question in one of the chapter reviews of my study book. Something about what do you do if you experience DCS at the surface. One of the choices was to go back down. I thought I remembered Lloyd Bridges doing that on Sea Hunt. Sort of like a makeshift decompression chamber. WRONG! The answer key said don't go back down!

This is not quite the scenario you asked about, but I think it's related: if you have microbubbles, you have too much nitrogen. I'd think you want a longer surface interval. Maybe very long. You ask, Wouldn't the bubbles be re-dissolved? I don't know. But if they are, your nitrogen load is even greater. That's why you want a longer SI.

And if you have any kind of symptoms, stop diving.

CAVEAT: I don't actually know what I'm talking about. But the fishes sure are pretty down there!

What you are talking about is in-water recompression for DCS, and it is a very controversial topic. Most experts recommend against it for a number of reasons, but not everyone agrees. One important reason against it is that just about nobody knows how to do it correctly.

Here is a Wikipedia summary:
In-water recompression - Wikipedia, the free encyclopedia

 

[Scared Silly]

No - you guys got fires or something? We're getting snow.

No fires, I speaking in terms of pow smoke - it is real dry here. Might get some snow this afternoon / tonight.