Surprising decrease in air consumption.

[Malpaso]

Saw a major decrease in my air consumption on two dives last night. We did a dusk dive, followed by a night dive. For the first time in my short diving career, I was under for a full hour on an 80AL, which may not be great for everyone, but is a noticeable improvement for me, especially cold water diving. Now there are a number of variable that may have contributed:

We never went deeper than 30'
We were really moving slow, just looking at the wildlife
I'm getting a lot more comfortable in the water
I feel "different" with a bp/w
I've been doing a lot of wind work at the gym, e.g., heavy bag, rowing machine

Anyway, first dive I hit the shore with 400#, the second I ended with 1000#.

 

[TSandM]

I suspect it's 2, 3 and 4 . . . You moved slowly, were more relaxed, and may have been more horizontal (so not wasting as much energy). But staying shallow makes for longer dives, too!

 

[dumpsterDiver]

Definitely the slower movement at night. At night, you tend to move much less, concentrate on the little creatures and if you are comfortable in this environment, it often translates to a more relaxing dive and lowered air consumption,

 

[DivemasterDennis]

The first three things the op mentioned are 95% of the reason for reduced consumption, and the first depth, is the cause of most of the improvement. Strangely, aerobic and anaerobic exercise that increases stamina usually increases lung capacity as well, and offsets any increased metabolic efficiency that comes with "getting in top shape." But Malpaso, keep up the good exercise habits and enjoy those 60 minute dives!
DivemastrerDennis

 

[TSandM]

Lung capacity is not changed by exercise, nor is lung size correlated at all with gas consumption, except in that people with large lungs are likely to be large people.

The bottom line on gas consumption is set by CO2 production. CO2 levels in the blood must be maintained within rather narrow limits for the chemistry of the body to work properly. CO2 elimination is directly related to the VOLUME of gas passing through the alveoli in a given period of time.

CO2 production is reduced by reducing muscle activity -- thus going more slowly, and also training muscles so that less effort is required to achieve a given amount of work, act to reduce the amount of CO2 that has to be removed from the body.

Agree that depth will have a profound effect on gas consumption, though -- probably more than any change in diver effort or efficiency, once one is past the initial very ineffective period as a diver.

 

[Poseidons Playground]

Good job man! I do a lot of adventuring and Im only up to 53 minutes with 300# left with my st80. For whatever reason or however you did it, good job and keep it up . . . . safely!

 

[mruseless]

Keep up the good work! For your next day dive, try and recapture that feeling of moving slowly, effortlessly, just looking at the fun stuff (but of course keep and eye on your buddy). You should find that over your next hundred dives or so, your gas consumption will steadily get better. Of course you will have some dives where you just weren't as comfortable and used more gas for a given depth, but overall you should see improvement. Congrats!

 

[tamas970]

...
We never went deeper than 30'
We were really moving slow, just looking at the wildlife
I'm getting a lot more comfortable in the water
I feel "different" with a bp/w
I've been doing a lot of wind work at the gym, e.g., heavy bag, rowing machine
...

As earlier said, #1-3 are clear reasons for lower consumption. #1&2 applies to the instructor with 5000 dives below his/her belt.

 

[Scuba.com]

Great job reducing your air consumption without resorting to those other pitfalls that newer divers succumb to, like skip breathing.

Relaxation and reduced workload on a dive are certainly the best way to reduce your air consumption.