How small is your SAC?

[TSandM]

It would be helpful to know the average depth at which some of these SAC rates were achieved otherwise a pointless measurement by itself.

????

The whole point of calculating your SAC rate is to normalize it to the surface (remove the effect of depth). I have calculations for dives which have ranged from average depths of around 60 to average depths of 15. It doesn't make any difference. What makes a difference is water temperature and exertion level (and anxiety!)

 

[don Francisco]

It would be helpful to know the average depth at which some of these SAC rates were achieved otherwise a pointless measurement by itself.

By definition SAC, surface air consumption, is compensated for depth. In theory (all other things being equal) ones SAC would be similar regardless of depth, though actual air consumption would be higher at greater depth.

Personally, my SAC averages slightly worse below 70 feet than on shallower dives.

 

[DwayneJ]

It was pointed out long ago that the Poll is flawed but it is fun to play along anyways. After all you are getting a pretty wide spectrum of involvement (divers with 25 to divers with 2500).

.70 -.79 but can get as high a .9+ if I have to "dig" to get my lobsters. Around 55-70'.

 

[Papa_Bear]

I only breath on the surface, otherwise I blow air into the tank at depth:mooner: Are gills cheating?:blinking:

 

[ScubaSteve]

I only breath on the surface, otherwise I blow air into the tank at depth:mooner: Are gills cheating?:blinking:

I do not know if they are cheating but they are at the top of my gift list .

 

[bowlofpetunias]

Interesting exercise. Anything that instigates self review is worthwhile. To me the value of knowing your SAC is dive planning and noticing changes to trigger post dive evaluation. If it changes.... why? pick the dive apart and figure out if you need to practice/review something.

Examples

Worst SAC .49 It was a boat dive unfamiliar site 26 metres 42 min. continual low level freeflow from reg, one of my buddies decided to play Olympic swimmer, my other buddy and I wound up doing a lost buddy procedure. Not a fun dive but well worth it for experience.

Best SAC .27 Shore dive familiar site, 13 metres 2hrs 6 min relaxed with my two favourite buddies.

Average SAC .34 according to my Uatec Smart Com over the last 88 dives

The only time it matters to anyone else is if you buddy with them (dive planning) or dive boat operators (dive planning).

I know divers better than me that use more air. I can work to become a better diver but they can't change their physiology. It is reasonable to take credit for skills you develop but not something you can't control.

 

[Diver0001]

Gas consumption at home, in cold water, is more in the low to mid .4's. I don't know why cold water raises my gas consumption, but it does.

Works like this for me too. In cold water I'm in the low .4's and in warm water in the low .3's no idea why. I answered the poll with .40 -.49

R.

 

[Rhone Man]

It would be helpful to know the average depth at which some of these SAC rates were achieved otherwise a pointless measurement by itself.

????

The whole point of calculating your SAC rate is to normalize it to the surface (remove the effect of depth). I have calculations for dives which have ranged from average depths of around 60 to average depths of 15. It doesn't make any difference. What makes a difference is water temperature and exertion level (and anxiety!)

Anecdotally, some people say that your SAC will gets slightly worse with depth because of increase in breathing resistance (and probably a bit of anxiety too). No idea if it is true, but it sounds logical.

 

[Tigerman]

Works like this for me too. In cold water I'm in the low .4's and in warm water in the low .3's no idea why. I answered the poll with .40 -.49

R.

Because in colder water your body use more energy to stay heated, alas you need more air?
Would seem to be a possible explanation anyways..