During my navigation dive in my AOW course, I very nearly ran totally, completely out of air.
The dive was separated into 3 parts:
1) Descend a few meters. Count fin cycles needed to complete 25m. We were diving off a boat 25m long.
2) Descend all the way to the bottom. Navigation in a straight line, with buddy on the compass and I counting fin cycles, and returning. Then it was me on the compass and buddy was counting fin cycles, to and fro. Distance covered: 25 m x 4.
3) Navigation in a square. Buddy was guiding by compass first, and I was counting fin cycles again. After the square was completed, we switched roles. Distance covered: 25 m x 8.
Upon finishing the exercise, I looked down at my gauges, and realised the air pressure needle was on zero bar (usually we ascend on 50 bar). I performed CESA, and fortunately there were still a few good breaths I could take from the tank. My instructor and buddy followed me up. On the surface, when I asked my buddy what his gauge read, he was on zero too.
I think this is what happened.
1) We were finning hard when we were doing our navigation exercise. I had to fin hard to keep up with my buddy, who was faster than I was. We were over-exerting ourselves underwater.
2) We were too focused on finning and our compass, we forgot to check our gauges often.
I suggest that students be told that the navigation exercise is not a race, to avoid over-exertion and to check gauges often.
EDIT: I must state that I was falling a little behind my buddy and instructor when I looked at my gauge and decided it was time to perform CESA. I didn't have any tool to sound a signal. When my instructor looked back (and up) for me, I gave him the OOA signal and continued up.
The dive was separated into 3 parts:
1) Descend a few meters. Count fin cycles needed to complete 25m. We were diving off a boat 25m long.
2) Descend all the way to the bottom. Navigation in a straight line, with buddy on the compass and I counting fin cycles, and returning. Then it was me on the compass and buddy was counting fin cycles, to and fro. Distance covered: 25 m x 4.
3) Navigation in a square. Buddy was guiding by compass first, and I was counting fin cycles again. After the square was completed, we switched roles. Distance covered: 25 m x 8.
Upon finishing the exercise, I looked down at my gauges, and realised the air pressure needle was on zero bar (usually we ascend on 50 bar). I performed CESA, and fortunately there were still a few good breaths I could take from the tank. My instructor and buddy followed me up. On the surface, when I asked my buddy what his gauge read, he was on zero too.
I think this is what happened.
1) We were finning hard when we were doing our navigation exercise. I had to fin hard to keep up with my buddy, who was faster than I was. We were over-exerting ourselves underwater.
2) We were too focused on finning and our compass, we forgot to check our gauges often.
I suggest that students be told that the navigation exercise is not a race, to avoid over-exertion and to check gauges often.
EDIT: I must state that I was falling a little behind my buddy and instructor when I looked at my gauge and decided it was time to perform CESA. I didn't have any tool to sound a signal. When my instructor looked back (and up) for me, I gave him the OOA signal and continued up.
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