SAC Rates - The Good, The Bad, The Average

[Colo Hippie]

OK – If this belongs in a different forum, mod’s, please move it (I’m fairly new to posting here) and by placing it here I am hoping for some intelligent and informed discussion and insight. Hopefully I will learn from this.

SAC rates – the good, the bad, and the average. What is your best, worst and average, recent SAC rate(s) for rec, non-Deco dives? And what is considered good?

I ask because I want to compare where my wife and I are (currently) versus those that have comparable experience and versus those with more/less experience. We both have between 100 and 200 dives.

I think SAC rates are a good comparison for divers because it is a measurement of the overall performance of the diver during the dive(s) regardless of depth, current, etc. I personally think this is a somewhat” level playing field”. Please educate me if I am wrong.

I consider both of us to be advanced intermediate recreational divers. By that I mean that we are both comfortable and confident in almost all situations encountered during recreational diving. We have not encountered every situation there is but have encountered enough to trust ourselves and each other. We review how to handle different situations and review skills before each dive. We are unusual in that we check each other’s gear BEFORE EVERY dive and ask each other a couple off the cuff “what if” questions as a quick mini review before each dive.

Below I have detailed both of our SAC rates for a recent trip to Roatan. Post up your recent SAC rates and thoughts/opinions/ knowledge/ etc.

TIA

Jeff	Bonny
0.467	0.515
0.52	0.416
0.438	0.451
0.459	0.452
0.456	0.405
0.439	0.451
0.425	0.412
0.538	0.402
0.573	0.437
0.438	0.475
0.406	0.419
0.475	0.459
0.44	0.446
0.439	0.393
0.425	0.405
0.462	0.409
0.426	0.429
0.421
0.427
0.437
0.45555	0.433882353

 

[tyesai]

I'm coming up on my 20'th dive and I just figured mine out for the first time last week and came up with .55

 

[raftingtigger]

I'd say those are pretty decent rates. Comfort isn't the only factor in what your SAC rate will be however. Work load, size, fitness, and possibly even gender play a factor. That said, you can probably use a comparison of YOUR SAC rates over time to see how relaxed you are under similar conditions. Comparing between divers is useful to see who should carry the larger capacity tank and probably not much else.

For comparison I'm 66", 140#, female, dive in cold water and have comparable experience. My SAC is about .40-.42

 

[Colo Hippie]

raftingtigger - your right, there are a lot of factors involved. That is why I did not describe conditions or diver size, etc, but posted the SAC for each dive and the average for the week for both of us. Some dives were more strenuous then others, on a couple of my dives with higher SACs I was doing some testing/ playing. I agree that for our experience our SAC rates our pretty good but we can both improve. I would like to see both of us in the .40 - .38 range and think we can reach it. I have tracked both of us from our OWC to now and average each dive trip individually to track our progress . Your right, comfort is not the only factor but does play a significant part, as with the many factors you mention there are others including water temp, etc.you bring up a great point about tracking your SAC rate over time, I am just curious to see what others are at and I think this would be a good thing for newer divers to look at/think about/compare/aim for. just my .02. . Please keep teaching me !!

---------- Post added April 13th, 2012 at 09:42 PM ----------

I'm coming up on my 20'th dive and I just figured mine out for the first time last week and came up with .55

When I was at 20 dives my SAC was right in line with yours. I hated how fast I sucked down my tank. Concentrate on your inhilation and exhale while enjoying the dive and before you know it down there with those "experts" and enjoy the diving

 

[ermaclob]

taking a sample size of 10 dives from my log book at depth ranging from 20-60 ft. my SAC is ranged from .357 to .286 the average is .325

---------- Post added April 14th, 2012 at 12:11 AM ----------

im 5'6" and weight 200 lb

 

[lowviz]

Colo Hippie,

Tom Mount, IANTD guru, was nuts about breathing -beyond nuts, mystical. In retrospect, this is not so surprising as he was also highly accomplished in Eastern martial arts. Which (I think) is why IANTD still encourages you to determine your SAC while resting on the surface, like watching television! Record your tank psi, block you nose with a mask or clip, start timing, and veg out until you are down to the last 100 psi or so. I first thought that this was just plain useless with respect to diving. I have since changed my mind on this.

According to Tom Mount, you must first learn how to breathe properly. (Something like: Diaphragmatic breathing - Wikipedia, the free encyclopedia) I'm getting there, but still have a way to go...

Like you, I enjoy testing and measuring things. The "couch SAC" idea turned out to be not so crazy. This SAC rate does not change very much and it gives a really good baseline for YOU when safe and completely unstressed. Get some extra value from that fill you paid for. Now when you find your SAC rates for various dives, you can compare these numbers to your absolute baseline. Divide the two SAC rates and you have a correction factor that relates to the stresses that you experienced on your dive. As the number of your surface and dive SAC measurements increases, you will be able to pick a very accurate correction factor for a planned dive. Welcome to the world of gas planning.

 

[TSandM]

I think there is not very much value in comparing your own SAC rate with other people's. There's a lot of value in following your own over time.

For example, my dearest dive buddy is a 6', fit man with no body fat. He's also one of the most beautiful divers I know -- absolutely quiet, relaxed, graceful, and in control of his dive all the time. His SAC rate runs close to .7. It is what it is.

Another one of my dive buddies is a fit 6' man whose SAC rate is consistently lower than mine.

Trying to achieve the SAC rate of someone with a lower metabolism, less muscle mass, fitter or smaller than you are is only asking to get into CO2 retention.

My SAC rate can and has almost tripled, between my lowest warm water amble and my most stressful line running experiences.

 

[diverrex]

I didn't realize it was a contest.

 

[Pook-60]

Very helpful discussion. Thanks LowViz for the full description.

Dane

 

[pjhansman]

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.