question about dc, free diving in between scuba dives

[coolazul]

For years I have always free dived in between my regular scuba dives. most of my dives are in california. i did this on dive boats in the channel islands, monterey catalina and san diego. also did it on my beach dives. no dive masters or instructors have ever told me this was inappropriate or dangerous. i asked a physician one time about increase in nitrogen and free diving and he said it was no problem because i was not breathing "compressed" air (several years ago). I was in Utila a few weeks ago and a 20 year old instructor reprimanded me for doing this (free diving) . She told me that it will cause the nitrogen to bubble in my system. I am a member of dan, i read their publications and have not seen any imperical data supporting the dive instructors view. Am I miss informed??

 

[DocVikingo]

As your question really is more related to decompression issues than medical ones, I have taken the liberty of moving it to this more appropriate forum.

Dr. Deco has responded to this inquiry before and will be able to provide a good answer.

Best regards.

DocVikingo

 

[pipedope]

First go read;
http://www.wkpp.org/articles/Decompression/why_we_do_not_bounce_dive_after_diving.htm

While I would be the last person to reference GI3 as the final authority on anything, his arguement is sound.

It is the compressing and quick decompressing that is the problem with free diving after scuba, not the amount of nitrogen you absorb during the free dives.

As for the real risk, it depends a lot on the dive profiles. The more nitrogen you have absorbed the more risk from a free dive after.

 

[DandyDon]

Think of a can of hot beer or soda, saturated in CO2, but stable. Now, shake it enthusiastically before opening it. Don't do that to your body when it's loaded with N2, as too much N2 can come out of solution too fast, causing the dreaded bubbles, bends, etc.

We discussed this recently on Basic Scuba, as so many are not being warned against this...

 

[Dr Deco]

Hello coolazul:

Vigorous activity following a dive is not a good idea – to put it mildly. This is a very good way to cause nuclei to form/grow in an individual with excess dissolved nitrogen. This is not a theoretical concept that adds a “maybe” to the risk of decompression. It is an extremely observable risk factor. We encounter this NASA decompression work.

This type of activity falls in the same category as surface swims or beach volleyball – all bad post-dive activities.

In addition, none of these nuclei-generating activities are included in decompression algorithms. Thus the whole of the decompression process is interfered with as regards subsequent dives.

Dr Deco :doctor:

 

[coolazul]

thanks, i appreciate the info.