what exactly is SAC rate and how can it be improved.

[coralcrazed]

I think its your breathing rate... right? the real question is how can it be improved? I have come across some devices that you breath through BUT... do they work? or is it just about diving exp. thanks

[quasimoto]

It is the amount of air that you breath at a given depth. Not sure of teh formula but I think it has been posted here someplace.
Best way to decrease your SAC is to relax, tuck everything in and breath slowly and deep. Being weighted correctly helps as well.

[CompuDude]

Your SAC is "surface air consumption". It tells you how much air you consume, in cubic feet per minute, at the surface. Easy math tells you how much you would then use at any given depth.

Breath smoothly, slowly and deeply. Be calm. More experience and your SAC will get lower on it's own. There are certain physiological limits, however... no way a 250# 6'3" man is going to breath as little as a 5' tall woman weighing under 100#.

Easiest way to determine your SAC is have your computer tell you (after you download it to your computer and tell it what size tank you used and how much gas you used). If your computer can't, you can figure it out yourself. Go to 33' and swim normally at that depth for 5 minutes. Note your starting and ending pressure, divide by 5 to see your average PSI used for one minute.

You'll need to do some math to determine how much that amount of gas used is in cubic feet for your size tank, since PSI is pressure, not volume. But once you know that figure (I'm too lazy to type it out right now), you can figure out how to convert the PSI used in one minute at 33', to cubic feet used in one minute at 33'.

33' is two atmospheres of pressure, which you should know from your open water class. Divide that number by two and you can see what the figure is at the surface (1 atmosphere, or 1 ATA). That's your SAC. It will probably be a number anywhere from .5 cubic feet per minute (cf/min) up to 1.5 cf/min.

This is your regular SAC. Your actual SAC at any given time will be lower if you are sitting still doing nothing, and dramatically higher if you are kicking hard into a current, or if you are scared and stressed out in some underwater emergency.

[DUnder]

Here is a link to help with all the SAC calculations
http://www.spearfishing.org/bruces_tips/java/gc.html

[Ricky01]

All good advice. You could always buy a bigger tank.......................