"Remove the snorkel from your mouth
On returning to the surface - blast clearing the snorkel nearly invariably leads to a shallow water black-out if the freediver has been close to his limits. Retention of the snorkel at depth complicates equalization and when diaphragm contractions begin can lead to the inhalation of water."
Please cite your source on this quote. As a free diver who has been diving since 1959, I doubt it is viable. Besides, who still uses "blast clearing"? Displacement is the method of choice, and starts before attaining the surface. If the free diver is experiencing diaphragm contractions, he or she is pushing the limits too far. I have never had any problems equalizing with a snorkel in my mouth, just as I don't have any problems with a scuba mouthpiece in my mouth.
Now, I'll get to reading the rest of this thread.
SeaRat
John C. Ratliff, CSP, CIH, MSPH
---------- Post added January 26th, 2013 at 06:42 PM ----------
Okay, I've read through the entire thread now, and think there are some things that need to be addressed. This was about the snorkel, first and foremost. Here is my "take" on the problems with jaw fatigue over a long period of snorkeling time. This could have to do with the resistance of the snorkel to the swimming forward speed in the water as much as the "weight" of the snorkel. I think the OpEd actually feels that it isn't the "weight" in the water anymore too. So far as the resistance in the water, that can be a problem depending upon the snorkel type, it's design, and the amount of "stuff" hanging high on the snorkel. I have used the "HyperDry" snorkel, for instance, and feel the resistance to the water when I swim.
I was the Finswimming Director for the Underwater Society of America, and finswimmers use a very different type of snorkel, which is mounted on the front of the finswimmer. They conduct open water competitions which are quite long swims sometimes too. Here is a link to the reasoning behind the finswimming snorkel:
The best snorkel for finswimming - Finswimming BayFinswimming Bay
In the text, they talk about "CMAS."
CMAS is the World Underwater Federation (Confederation Mondeals des Activities Subaquatiques in French), which governs underwater competition activities worldwide. The
Underwater Society of America governs these activities in the United States of America (both acronyms are "USA"). Michael Gower is now the Finswimming Director for USA, and took over from me in the 1980s.
Anyway, I diverge from the topic; the snorkel for finswimming is the most streamlined snorkel available, and would alleviate any problems with jaw fatigue.
The other topics have to do with Shallow Water Blackout, and I have studied this topic extensively. However, it deserves its own thread, and I will soon create it (or find one already there, perhaps), so we can discuss SWB in more detail. But I will say that there is a lot of myths about this topic, some of which came up here. Take what was said here with a grain of salt; there were some good ideas, but some that I consider somewhat off-base from the basic physiology of SWB. More on another thread, and I'll probably blog it too, later...
SeaRat
John C. Ratliff, CSP, CIH, MSPH
