Performing a CESA After Exhale

[happy-diver]

Unbalanced regs give you a bit of a warning, balanced regs not particularly

Who's diving unbalanced these days


Solo seems to have become, the where do I put any of my thoughts forum

 

[boulderjohn]

When the US Navy trains divers on buoyant ascents for submarine escapes, it teaches them to exhale fully before beginning the ascent. THere will still be plenty of air in the lungs, even enough to cause an injury, so they continue to exhale as they ascend.

 

[oly5050user]

I think people are missing his point. He’s not talking about running out of “Air” before reaching the surface, he’s talking about the requirement of exhaling during ascent to prevent an over-expansion injury.

I’ll give a shot at the answer. If your lungs are truly empty, they can’t expand upon ascent, and therefore exhaling is unnecessary. In reality, some air will remain and can expand, and therefore upon ascent you should try to exhale as more gas “becomes available”. As someone else stated, the gas in your tank also expands, and you often get a breath there as well to help during ascent. I think this is why “blow and go” isn’t recommended; even if you think your lungs are empty, air can still expand resulting in over-expansion injuries.

I’ve never done a “real” CESA from more than about 4 meters, so maybe I’m a little off base here and would like some verification of my answers.

Gas in tank does not “expand” what occurs is ambient pressure decreases during ascent allowing diver to take a breath or two or three. This is one reason why regulator stays in mouth during cesa. Other reason to keep regulator in is to avoid possible aspiration on water