Diving for 2 minutes to 20 feet or 10 feet and coming to the surface

[spoolin01]

Rare anecdotes aside, what is the practical risk of lung over-expansion coming up from 10-20 ft?

If this information in Wiki is to be believed - and if I'm getting the definitions right - at the end of typical inspiration you have about a 100% capacity buffer against over-expansion. Even allowing for some differences as to how we breathe on scuba and what those numbers mean in this context, it seems like that's a pretty good insurance policy.

How common is this scuba injury at 10ft anyway?

Regarding the lung information at Wiki, I was surprised to see that a typical breath is less than 20% of total lung capacity.

 

[boulderjohn]

I am curious as to why you want to keep going up and down like this. If you are on scuba, why not just go down and stay down?

 

[scubadude223]

I do it because I am collecting rocks and shells.

I I clean them on the raft and go back down.

I I enjoy going up and going back down.

I I just didn't know if short 30 second dives were dangerous or posed a greater risk.

I must say again. I do not hold my breath and would never on a dive. I am just trying to figure out the short dive thing and if it were a danger.

 

[boulderjohn]

It is commonly believed that repeated ascents and descents are not good for the body. It is for that reason that scuba instructors are allowed to spread CESAs over a number of dives, so they are not dooing too many in succession.

Why not take a collection bag down with you, swim around until you have it full, and then go to the surface?

 

[nimoh]

As others have mentioned, you should forget about scuba for these repetitive 30 second dives as it just isn't practical.

You will be much more mobile swimming around on the surface in your wetsuit with a mask, snorkel and fins than when carrying 50lbs of scuba gear. When you see something you want to collect, hold your breath and swim down to get it. you can hold your breath for 30 seconds can't you?

 

[scubadude223]

But if I chose to do it,what would my risks be.

I I haven't been able to find an answer.
I know it's not a normal thing but what would the risk be.

 

[boulderjohn]

But if I chose to do it,what would my risks be.

I I haven't been able to find an answer.
I know it's not a normal thing but what would the risk be.

The risk would not be decompression sickness--not by a long shot.

If you don't hold your breath, there is not so much danger of air embolism.

As mentioned, scuba instructors often find themselves in a situation when they must do multiple ascents and descents. It is considered to be hard on the body, they do all they can to avoid doing too many of them. One of the reasons for it is the issue known as bubble pumping. For information on that, check out this thread: http://www.scubaboard.com/forums/basic-scuba-discussions/487628-bubble-pumping-theory.html

 

[nimoh]

You would have the same risks as any scuba dive as you were taught in your OW class with a decreased risk of DCS due to the depth and an increased risk of ear barotrauma due to the up and down.

However, that is off the top of my head and I am no expert. I would take what boulderjohn says to heart as he is usually pretty on top of things. I always thought CESAs were spread out becuase too much up and down is hard on the ears, but perhaps there is more to it.

I think the most likely reason that you are not getting a clear answer is that people just don't dive those profiles, so there has likely been very little if any research on them. In theory, based on my limited knowledge, it doesn't sound all that risky.

 

[scubadude223]

Thanks,

i can can find very little on the subject.

I mi have started diving in this style. I can extend my dives and can explore and find things that normally can't be found.

I I will have to look into it more.

 

[boulderjohn]

I think the most likely reason that you are not getting a clear answer is that people just don't dive those profiles, so there has likely been very little if any research on them. In theory, based on my limited knowledge, it doesn't sound all that risky.

As I tried to indicate, doing this is exremely rare, primarily because most people, including me, don't see the point in it. If I were looking for shells and rocks on scuba at a depth of 10-20 feet, I'd sure find it a lot easier to swim around on the bottom, searching and putting what I find in a collection bag or box, then making one ascent with the whole collection of loot. I think most people would.