SAC Rates - The Good, The Bad, The Average

[waterpirate]

I think more attention needs to be given to " how to breathe" as low viz said, but agree it is not a contest. My buddy " big John" is as tall as me 6', but his waist is 4-5 inches lower than mine. The man is all torso. His sac rate is very high at rest cause his lung volume is huuuuge!

The ability to control your breathing during exertion or stress should never be de-valued, it could save a divers life.
Eric

 

[Rich Keller]

Gotta go with TSandM on this one. One size definately does not fit all. My SAC varies from .375 on a relaxed drift dive in Coz to a .7 on a cold, murky, task loaded, drysuit dive in the north. It is what it is.

The good news is, my SAC is still improving. The reality is it will never be a low as my 120 lb wife.

If everything else during the dive the same for both then your wife's rate will always be lower due to a smaller lung capacity. The lung capacity of any diver will play the largest part in determining their SAC rate. With more hours in the water your rate will go down but there is a natural point for everyone that it will never go below.

 

[MXGratefulDiver]

We're all different, and there are a lot of factors that can determine how much air you will use on a given dive. If you're interested in learning more about not just air consumption, but how to plan and manage your air supply for a given dive, I wrote an article which is posted on my website that you may find useful ...

NWGratefulDiver.com

... Bob (Grateful Diver)

 

[redacted]

It is useful to know your limits and how various conditions effect your SAC, and how you can manage your SAC. In one of my courses, I did a baseline on my consumption rate to estimate the best I could do. Sitting in an easy chair (I'd bet a warm bath would work) with regulator and mask (to prevent nose breathing) you take a measurement. It could take the better part of an hour to get a good measure. That gave me a result of .25 cu ft per minute. So that is my limit. I do easy warm water dives at around .45 (usually plan my gas at .5). If I need to streatch my gas a bit, I can work on mellow slow breathing and get around .35 to .4). Cold water requiring 5mm will add .1 to .2. Work will add .2 to .5. But even in a higher SAC dive, I know I can slow it down and rest for a period and my SAC will drop back to about .5.

Bigger tanks are an option in some cases. In others, it is nice to be able to exercise some control over your SAC, dive plans permitting.

 

[Tigerman]

I have full control of my sack..
Ohwait.. this was SCUBAboard :blush:

On the serious side though, my SAC varies wildly with gear configuration and what I do on a dive.
A "resort dive" ala what youre doing in the caribbean Im in the .5s, donning a drysuit and puddeling about in my local cold-ass lake Ill be in the .6s

Trying to find the tow hooks and attach chains to a digger who went through the ice and sunk up to the cabin in the mud at the bottomn with -25c air temps and water freezing over behind me as I swam actross the hole the digger made.. A LOT more..

 

[Slamfire]

These are some of my SAC rate readings. I used to measure it a little more often than I currently do. Still, I do measure them regularly, just not everytime. First column is dive site, second is avg depth, 3rd=psi used, 4th=rated pressure, 5th=tank capacity, 6th=time in mins, 7th=sac rate.

Roatan	25	1500	3000	77.4	39	0.565
Whytecliff	51	2500	3442	131.4	58	0.646
Whytecliff	51	2450	3000	77.4	40	0.621
Whytecliff	43	2400	3000	77.4	42	0.640
Whisky Cv	46	2330	3000	77.4	38	0.661
Whisky Cv	57	2750	3000	77.4	36	0.723
Kelvin Gr	46	2300	3000	77.4	49	0.506
Kelvin Gr	44	2500	3000	77.4	49	0.564
Mermaid C	43	2000	3000	77.4	37	0.606
Mermaid C	60	2250	3000	77.4	36	0.572
Lookout Pt	58	2400	3000	77.4	38	0.591
Cliff Cove	47	2850	3000	77.4	49	0.619
Boyer Is	44	2750	3442	131.4	56	0.803
Boyer Is	57	2900	3442	131.4	55	0.738
Coopers G	39	1500	3000	77.4	32	0.554
Coopers G	54	1100	3000	77.4	17	0.633
Tuwanek S	46	2350	3000	77.4	53	0.478
Tuwanek N	43	2650	3000	77.4	56	0.530
VT100	38	2600	3442	131.4	81	0.570
Sasamat	44	1750	3000	77.4	32	0.605
Sasamat	18	900	3000	77.4	22	0.683
Larsen Bay	47	2100	3000	77.4	41	0.545
Larsen Bay	37	2250	3000	77.4	52	0.526
Porteau	40	2400	3000	77.4	53	0.528
Porteau	36	2300	3000	77.4	50	0.568
Porteau	52	2400	3000	77.4	39	0.616
Lions Bay	52	2600	3000	77.4	51	0.511
Lions Bay	49	2700	3000	77.4	56	0.501
Whytecliff	39	1400	3000	154.8	61	0.543
Sept Morn	43	1350	3000	154.8	51	0.593
Riv Tow L.	52	1300	3000	154.8	51	0.511
Snake Is.	50	2000	3000	154.8	54	0.760
The Cut	61	1300	3000	154.8	43	0.548
Whytecliff	41	1400	3000	154.8	49	0.657
Whyte Islet	35	1000	3000	154.8	46	0.544
Woodlands	52	1600	3000	154.8	51	0.628
Nakaya	54	1600	3000	154.8	50	0.626
Granthall	30	900	3000	154.8	50	0.487
Furry Creek	55	1500	3000	154.8	48	0.605
Furry Creek	53	1200	3000	154.8	46	0.517
Snake Is.	62	1800	3000	154.8	47	0.686
Saskatchewan	63	1900	3000	154.8	50	0.674
Whytecliff	94	1100	3000	154.8	25	0.59
Furry Creek	49	1400	3000	154.8	56	0.519
Furry Creek	52	1300	3000	154.8	45	0.579
Kelvin Gr	45	2500	3442	131.4	66	0.612
Ansell Point	55	1600	3000	154.8	54	0.573
Ansell Point	51	1100	3000	154.8	43	0.519
Copper Cove	57	1700	3000	154.8	49	0.656
Copper Cove	56	1000	3000	154.8	39	0.491
Lookout Pt	42	1900	3000	154.8	83	0.52
Lookout Pt	52	slinged bottle used	60	0.568
Whytecliff	52	1700	3000	154.8	58	0.587
Porteau	31	1600	3000	154.8	76	0.56
Porteau Wall	61	slinged bottle used	43	0.632
Porteau	30	1700	3000	154.8	81	0.567
Whytecliff	59	1600	3000	154.8	55	0.538
Whytecliff	55	1300	3000	154.8	48	0.524
Caulfield	38	1800	3000	154.8	77	0.561
Caulfield	49	1000	3000	154.8	39	0.532
Caulfield	46	1800	3000	154.8	71	0.546
Caulfield	33	slinged bottle used	69	0.542
Whytecliff	52	2200	3000	154.8	80	0.551
Gilboa	28	2000	3000	77.4	50	0.558
Whytecliff	55	2350	3000	154.8	87	0.523
Whytecliff	55	1450	3000	154.8	51	0.55
Whytecliff	48	2000	3000	154.8	80	0.526
Kelvin Gr	51	2200	3000	154.8	81	0.551
Caulfield	32	slinged bottle used	63	0.541
Whytecliff	48	2400	3000	154.8	89	0.567
Kelvin Gr	58	2400	3000	154.8	84	0.535
Furry Creek	66	1800	3000	154.8	45	0.688
Furry Creek	48	1100	3000	154.8	46	0.503
Whytecliff	54	1800	3000	154.8	55	0.641
Sack Rock	48	1500	3000	154.8	56	0.563
Piper Point	58	1200	3000	154.8	44	0.51
Caulfield	24	1500	3000	154.8	76	0.59
Whytecliff	76	slinged bottle used	65	0.66
Fearney	60	1600	3000	154.8	52	0.563
A-Frame	53	slinged bottle used	44	0.546
The Express	49	2000	3000	154.8	69	0.602
The Cut	67	slinged bottle used	70	0.718
Furry Creek	41	1700	3000	154.8	66	0.593
Furry Creek	47	1300	3000	154.8	53	0.522
Whytecliff	49	2000	3000	154.8	77	0.539
Rock Garden	48	2400	3000	154.8	84	0.601
Octo City	49	3800	3000	77.4	63	0.626
Boulder Pt	50	2700	3000	77.4	49	0.565
Alouette Lk	55	2200	3000	77.4	30	0.71
Alouette Lk	34	2500	3000	77.4	56	0.567
Buntzen Lk	41	2200	3000	154.8	94	0.539
Buntzen Lk	22	900	3000	154.8	51	0.546
Whytecliff	40	1600	3000	154.8	79	0.472
Whytecliff	72	slinged bottle used	66	0.614
Tuwanek	45	1200	3000	154.8	51	0.514
Tuwanek	47	1200	3000	154.8	41	0.623
Pavillion Lk	58	1000	3000	154.8	32	0.585
Pavillion Lk	39	1200	3000	154.8	53	0.535
Whale Rocks	55	1500	3000	154.8	47	0.618
James Island	51	1200	3000	154.8	48	0.507
Porteau Cove	46	1700	3000	154.8	76	0.482
Porteau Cove	30	1000	3000	154.8	49	0.552
Cates Park	36	1700	3000	154.8	71	0.591
Kelvin Gr	56	1300	3000	154.8	42	0.592
Buntzen Bay	49	1500	3000	154.8	42	0.742
Buntzen Bay	48	1300	3000	154.8	58	0.471
Whytecliff	68	slinged bottle used	68	0.645
Cultus Lake	38	1400	3000	154.8	57	0.589
Whytecliff	50	1500	3000	154.8	52	0.592
Whytecliff	72	slinged bottle used	88	0.578
Whytecliff	41	1200	3000	154.8	47	0.588
Whytecliff	52	1500	3000	154.8	53	0.567
Kelvin Gr	66	1300	3000	154.8	36	0.621
Mermaid C	55	1600	3000	154.8	63	0.491
Rock Garden	52	slinged bottle used	62	0.517
Furry Creek	62	slinged bottle used	85	0.555
Whytecliff	48	1400	2640	215.4	73	0.637
Brittania Beach	31	1100	3000	154.8	61	0.48
Brittania Beach	33	900	3000	154.8	44	0.528
Collingwood	61	1500	3000	154.8	52	0.523
Anvil Isl	61	1500	3000	154.8	50	0.543

 

[fncrow]

On normal 50min shallow reef dives with an AL80.

Average about .55
Lowest .42
Highest .72

and im at 60 something dives

 

[Tigerman]

I think more attention needs to be given to " how to breathe" as low viz said, but agree it is not a contest. My buddy " big John" is as tall as me 6', but his waist is 4-5 inches lower than mine. The man is all torso. His sac rate is very high at rest cause his lung volume is huuuuge!

The ability to control your breathing during exertion or stress should never be de-valued, it could save a divers life.
Eric

As a means of saving gas, I dont agree that it needs a lot of attention or that it "could save your life".
Playing around with your breathing by breathing shallow, skip-breathing and such to extend your bottomn times is not something I am a fan of, for co-retention and other reasons.

As a very effective way of controlling your mental state and avoiding stress and panic however, breathing is key and the keywords is deep and slow..

 

[Rhone Man]

I try to monitor my SAC from dive to dive just to spot patterns. I realised very early that if I am just "sightseeing" my SAC will normally be around 0.45 or so. But if I hunt lobster it balloons to 0.55 or higher. It is also suprising how much higher my SAC is when the water gets colder.

 

[Colo Hippie]

Great discussion all, thank you all for your input/incite:cool2:


Lowviz - I like that, and now my wife will love you for me making her breath a tank while sitting and watching tv .

TsandM and a couple others - I did not want this to be a contest, I was hoping for a conversation and learning experience for myself and others.


NWGratefullDiver - Thank you and I will be reading your article

waterpirate - I agree, what you said is part of what I was trying to communicate. How to control your breathing. I know I struggled at first with it. I hated being the guy that ended the dive for the group.

What suprised me with diving is that we live at 8,500ft and I am a runner. I run 5 & 10K's and some shorter distances. I can run a 5k in 15:53 consistently. That is a very competitive time and my SAC rate was pretty bad when we first started diving. I have had to work on it to get it down to the .455 I am at. I was really suprised that my SAC rate was some what bad when I know what kind of shape I am in.

Now I am aware of my breathing while diving and have much better control than I did at first, thanks in a very large part to threads i have read on this board!!!


My next stop is ??? who knows ???