bourj, I had similar experiences as you during my 25 first dives six years ago. I'll show you how my figures improved from the beginning to present date after 570 dives.
I am a middle-aged male with some extra bioprene in the middle. My BMI has varied between 29 and 31. Apart from regular diving, I might do 0-2 hours of relatively easy fitness per week. Six years ago I thought that a single tank (10L) with weights (12kg/26lbs) was heavy. Now with 100kg/220lbs of technical gear and a camera, it feels a bit heavy.
Six years ago, my very first 25 dives showed the following stats:
- Average surface consumption (rmv) 37.1L/min or imperial 1.05, i.e. very similar to your figures
- Min 0.65 (23L/min) and max 1.85! (65.4L/min). This includes some of the first training dives and you can see I was really breathing a lot at times.
Already the next 25 dives showed a significant improvement:
- Average 0.55 (19.3L/min), i.e. the consumption almost halved. Now I was feeling more comfortable in water, however still swimming rec style.
- Minimum 0.40 (14.3L/min) and max 0.86 (30.2L/min).
One year later, the stats are slightly worse:
- Average 0.67 (23.7L/min) diving in cold waters (dry suit) and 0.65 diving in warm waters (wet suit). The likeliest explanation is that I was gradually extending my comfort zone and diving deeper and longer.
- Minimum 0.44 (15.6L/min) and max 1.33! (47l/min). The max occured during a CMAS P3 training dive. Other maximums occurred during pinnacle dives like my first penetration to a wreck at 100ft/30m depth. However, the minimum was reached at a docile sand bottomed site and a couple of days later on the same site I was breathing almost triple the amount.
- Notice how big the variation was between min and max.
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Now six years later I have certs for cave diving (could not foresee that happening), trimix and solo diving. The stats are:
- Average 0.51 for open water, low ciz cold water with dry suit. Min 0.45 and max 0.60. So there is much less day-to-day variation. The max occurred during 96 minute 180ft/55m pinnacle dive to a famous but demanding wreck.
- Average 0.49 for open water, high viz warm water with dry suit. Interestingly the minimum 0.39 and the maximum 0.57 occured during the same day in Hong Kong (the viz was not particularly good). The difference was that the first dive was task-loaded since we helped a local university in preparing a dive site for academic research.
- Average 0.54 for "easy" cave dives. "Easy" means bottom times of 40 minutes at 100ft/30m plus deco in 4ºC/39ºF water. Min 0.47 and max 0.60.
- Average 0.58 for more demanding cave dives. Min 0.46 and max 0.76. The max figures correlate to various pinnacle dives, e.g. a half-mile penetration into a cave south of the Ural mountains near Siberia, total dive time 113 minutes. Or a cave traverse at 190ft/58m - incidentally one of my dive pals got a DCS hit on a similar dive couple of months later.
The lesson here is that you will gradually become comfortable at whatever dive level you are diving at. When you extend that range into new pinnacle dives, be prepared that your gas consumption will increase. As new diver, the increase is significant. As a more experienced diver, the increase is smaller, but still there. You'll need to include it in your calculations plus a margin for situations when s*** hits the fan.
Weightwise, in the beginning I used 12kg/26lbs. Gradually over two or three years I decreased this to zero weights (dry suit, normal backplate, wings). But with increased dive range into caves in cold water, I have added back 4kg/9 lbs. This compensates for increased buoyancy of empty tanks but especially for increased need for additional underwear during longer dives.