What's a good SAC

[BlueTrin]

The one that I always liked that is similar is, there are three kinds of people in the world. Those that are good at math and those that are not.

And the computer science version: there are 10 kind of people, those who know binary and those who do not.

 

[Imla]

don't know about good or bad sac-rates.. but one of my buddies still questions why I felt the need to get a rebreather.
Examples of my sacrates: Max sacrate on my GUE C1 was 12l/min. (Moderately cold water/France)
My last scooterdive 9,8L/min. (And that is artificially high due to warm tanks and 2c water)
Normally I Average around 11-12l/min.

 

[Jay]

Hi @MargaritaMike

SAC is reported as pressure/time (psi/min) and is cylinder dependent. RMV is reported as volume/time (cf/min) and is cylinder independent. I would suggest converting your SAC to RMV for easier comparisons. I'm assuming you have a Perdix AI or a Teric, that gives you only SAC.

I would think that if my Perdix AI says that I am breathing 16 psi/min, it doesn't care what size tank I have. It sees what the tank pressure is at time zero and then at time 1 and subtracts one from the other. Why would it be tank size dependent?
Cheers -

Both correct ... it's just a question of wording. Perhaps "SAC is reported as pressure/time (psi/min) and is cylinder dependent when comparing across different cylinders".

My post is more of a PSA as eariler on I was confused until I remember RMV is volume (L or cf/min and SAC pressure (PSI or bar)/min.

 

[rhwestfall]

I use too many different tanks to "effectively" use SAC. Normalizing to RMV is best for me to evaluate or benchmark information.

 

[scubadada]

The advantage of calculating your RMV over all of your dives is that that average and standard deviation take into account all of the dives you do. This includes the water temperature, current, visibility, type of dive, etc. I have my RMV for the last 1266 of 1282 dives. I did not start collecting this information until I had 443 dives. Many of my dives are drift dives in SE Florida, but I have also dived the Red Sea, Cocos, Galapagos, and many Caribbean locations. So my average RMV of 0.36 cf/min is very useful to me. The standard deviation of 0.04 means that 95% of my dives are between 0.28 and 0.44 cf/min. The actual range is 0.27-0.63 cf/min. For me, body temperature is at least as important as exertion level in determining my RMV. Because of this, I tend to choose my environmental protection to keep me warm. Following your RMV may also prove very useful.

 

[rhwestfall]

I should add to my earlier post where I listed my numbers that being 6'-7", and a former athlete seems to make an impact on my data. Funny thing is that my air consumption became better after having left sports, but dive experience also may have been in play. I still am different from my 5'-2" wife too

 

[BlueTrin]

I should add to my earlier post where I listed my numbers that being 6'-7", and a former athlete seems to make an impact on my data. Funny thing is that my air consumption became better after having left sports, but dive experience also may have been in play. I still am different from my 5'-2" wife too

Do you mean that having more muscle mass increased your air consumption ?

 

[rhwestfall]

I got better consumption rates not having to furnish a competition tuned body...

 

[Diver0001]

The question is threefold: 1) What is a good SAC?,

normally I would expect experienced divers to have about the same air consumption diving in calm conditions as they would sitting on the couch watching TV.... give or take. This number will vary depending on a number of factors so what's good for someone else may not be good for you. It's personal and it's not a competition.

2) What is your average SAC?, and

In calm conditions usually about 12-13l/m (I think that's something like 0.45cf/m?). Normally this is drysuit diving in cold water with doubles. It goes up or down slightly from there depending on the day. It can go up a lot if the dive involves a lot of physical effort. Getting under 12l/m is something I can normally only expect in warm water using light gear.

3) When does your SAC increase or decrease during a dive?

Mostly as a function of effort and water temperature.

R..

 

[scubadada]

Relating RMV to body size is overly simplistic. I am 5' 10" about 190 lbs, I have a relatively low RMV and always have.