boomx5
Contributor
Okay, so grab your tank and regulator, get on the treadmill on high, and watch a porn flick . . . will that work? :blinking:
That may take a set of doubles and a loooooonnngggg decompression!
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Okay, so grab your tank and regulator, get on the treadmill on high, and watch a porn flick . . . will that work? :blinking:
Sure, then double it 'cause your working, double it again for excitement, adjust it for depth ... that'll be close, but I wouldn't bet my life on it.
Guys, what does SAC stand for? SURFACE Air Consumption, exactly. OF COURSE this will be different from the air consumption rate at a given depth, under given circumstances.
SAC rates vary depending on what your doing and at what depth your doing it at. If you're in still water, neutrally buoyed just cruisin' along relaxed, why would it be any different than sitting in a chair watching the news for example. I might use MORE air watching the news You need a baseline to work from on the surface in a chair is as good as any. Just don't use it to plan a deep dive in a strong current. You'll need to adjust for each dive. The more you dive and pay attention to your SAC the better your adjustments will become. I timed how long it takes for me to use 500psi of gas under different conditions. I use that base line to plan gas consumption for my dives. Even that needs adjusting if your fitness changes. My SAC at 55 years old is higher than when I started at 15.
The key thing is that you should be doing these measurements under different conditions because your SAC rate isn't a number ... it's a range ... and your actual consumption under any given condition will fall somewhere in that range.
What I do with my students is have them take two sets of measurements while diving. One set is taken while kicking very hard ... to simulate working against a stiff current. A second set is taken while swimming slowly and looking around ... to simulate normal, currentless diving conditions. The first set is called "working SAC" and the second is called "resting SAC". Your actual consumption on any given dive will fall somewhere in between those two values ... just as actual miles per gallon in your car will fall somewhere between the familiar "City miles" and "Highway miles" numbers you see posted for your particular type of vehicle.
The real key to looking at your consumption rate is to remember that it's just one piece of information you need in order to figure out how much gas you will need for a given dive.
My advice is to take before and after readings over the course of several real dives, and use the simple arithmetic needed to calculate your surface consumption for each of those dives. You will notice that there will be slight variations ... which will be due to differences in diving conditions and your own personal physical condition on each given dive. Ask yourself what you experienced on each dive that could have caused the rate to go up or down slightly, and look for trends. By doing so you will develop a much better idea of how to accurately estimate the amount of gas you need for any given dive.
... Bob (Grateful Diver)
Then one resting SAC and ones leasurely dive SAC and anything below a hard working SAC is usless because one must plan for the worst case scenario of being stressed out and paniced at the end of a dive. Otherwise one will always have less gas than necessary to make a "safe" dive, correct?