Mantaray95616
Registered
I haven't yet got theknack of selectong quotes.Hey, if you look back on my posts, the original courses , before NAUI was created, were based on students mastering skills at their own pace and then being tested. Maybe failing is the wrong word; but if a student is unable to complete a necessary skill before the course ends (they can make as many attempts as they like) they cannot be certified. They are still welcome to re-enroll in later courses. What's so different between our two methologies?
In the two specific cases I brought up it was a matter of judgement. In my opinion neither of them would ever be comfortable in an underwater environment and I acted accordingly and with regret.
I have two comments regarding bouyant and free ascents.
At the depths you would be normally diving, fully emptying your lungs is unnecessary and can make the ascent more stessfull. Maintain an open airway and let change in ambient pressure do its work of expelling excess air. Does anybody know why the navy recommends completely emptying the lungs.? I can only quess that it is because of the extreme depths and a pressure differential on leaving the sub.
The second is regarding the Royal Navy's use of oxygen. Pure oxygen was used by the navy's frogmen in rebreather sets (no bubbles) to avoid detection.
Pure oxygen becomes TOXIC at a depth of 33 Ft. A pure air mixture becomes toxic when the partial pressure of oxyen reaches 14.7 psi (165 ft). This is one of the reasons mixed gas diving evolved. The human body can tolerate a certain amount of toxicity.