Sunday I tried to measure residual volume. On a dive to 10 meters, I exhaled completely for over 10 seconds, emptied my mouth and pinched my nose to close off the expanding mask. When I got to the surface, I measured the air that I could exhale in 10 seconds and it was 1.1 liters. Given the method used, it should be read 1.0-1.3, I think. Head down or head up didn't seem to make any difference. Does that sound like a measurement of residual?
Since my vital capacity measures 5.2-5.8 (the higher number is immediately after stretching), I can leave the surface with a total air volume of 6.4 to almost 8 and should reach residual at 43 to 56 meters with the Beuchat mask or get a complete mouthful of air at 36 to 46 meters. When I tried, the 35 meters (no packing) worked OK, but at 45, I couldn't fill my mouth. Carlos, who patiently supervised all this, commented that I lost some air on the deeper dive.
Since a full exhale plus mouth full dive to 10 meters is possible, the lungs must be able to squeeze down to about half a litre. Just thought that I would share and find out if my logic will pass review.
Aloha
Bill
Since my vital capacity measures 5.2-5.8 (the higher number is immediately after stretching), I can leave the surface with a total air volume of 6.4 to almost 8 and should reach residual at 43 to 56 meters with the Beuchat mask or get a complete mouthful of air at 36 to 46 meters. When I tried, the 35 meters (no packing) worked OK, but at 45, I couldn't fill my mouth. Carlos, who patiently supervised all this, commented that I lost some air on the deeper dive.
Since a full exhale plus mouth full dive to 10 meters is possible, the lungs must be able to squeeze down to about half a litre. Just thought that I would share and find out if my logic will pass review.
Aloha
Bill