Air integrated computers do a better job of this. The readings they take are more accurate, and you an examine your consumption by dive phase. For example if you are fighting a current/flow during one part of your dive you can see how much more air you used then vs just hanging for your 5 minutes safety stop.
Hi James. Thanks for all the great videos! I'm a beginner, so this might be a very stupid question: if I'm 10m below the surface, pressure is 2 BARs. When I inhale (supposedly the same volume as at the surface), I'm getting twice the amount of oxygen (for the same volume) I would get at the surface. This would mean that I could breathe twice as less at 10m deep. Since this is not the case, where is the error in the above? Is the amount of oxygen the body can take from a certain volume of air independent of the pressure that air is at?
Great video! I like data and stats ss well, but for all my drives I just have max depth recorded. How do you come up with average depth without being preoccupied with how long you're at various depths your whole drive? Thanks🤙🏼
The simple Suunto Zopo Novo computer I used had an average depth when you went into the logbook & I think most computers do as well. And if I'm not mistaken you can also use this equation to find SAC rate at a certain depth instead of average, which should make it more accurate, but I am not sure so please take that information with a grain of salt.
Awesome video. I believe this calculation is actually for RMV rate instead of SAC rate. At least the .47 cfm number is the RMV rate. If you run the same numbers using SAC rate calculation it comes out to be 17.5 psi.
Hi Yonnea... the easiest way is to buy an Air Integrated computer and that will tell you your SAC rate as part of the dive log, but other wise it is ((Gas Used)➗(Ave. Depth Atmospheres))➗Dive Time Minutes = SAC Rate. Hope that helps! James
Why do you use 80 cubic feet for SAC rate calculations when it only holds 77 cubic feet at 3,000 psi? I’m a newbie and as near as i can tell theres a lot of confusion re tank internal volume, compressed air volume, rated pressure, working pressure, etc., etc. Help!!
I've also very very rarely gotten a tank at 3000psi, it's usually 32-3400psi. Very good thing to keep in mind for planning to keep your turn around time conservative. Don't want to be 300psi short on your return
Can't wait for the video on how to improve SAC rate. My wife's is about 60-70% of mine normally and I always need to call the dive first. When we went lionfish hunting, we evened out because she was my spotter and keeper.
Yuriy D, my buddy, the ladies always win this one. I'm a Tec Instructor and my wife is AOW and she kicks my butt in SAC Rate... But I will give you all the hints and tips I can in the upcoming video. I'm not sure when it's coming out, but it is coming! Dive safe! James
Easy way to improve your sac! Take a double 12l tank and your sac is the half of them what you have with a single tank. Start to breath like you are on the surface. Breath in, breath out, break. And not breath in, break, breath out.
Extremely useful video! So according to this calculation my SAC rate for my final CMAS* + Drysuit course dive was 17,5 l/min. Diving with a single 12l 300Bar tank to a max depth of 15,4m for 40min.
Ok, Good Video... But I have a question... I'm following along with the imperial example and have questioned my first calculator... But I keep getting 2200 × .026 = 57.20 cu.ft, am I missing something or was this an error ?
My sac is telling me this isn’t very useful for the average diver… women have smaller lungs, muscular guys consume more air, currents, depth vs stress… too many variables to measure them.
So even breathing pure oxygen wouldn’t reduce SAC rate? Just thinking breathing rate would go down because you’re getting more oxygen in each breath. But then again that statement ignores the role of CO2 in triggering the “need to breath” reflex.
Just so everyone is clear.... When your dive guide or Instructor takes a "Nap" between dives, they are actually demonstrating role model behavior and have your best interests at heart.
I seem to breathe like a horse, regardless of how calm and slow I breathe, concentrating firmly on it. Easily blown through my entire 15 litre tank when the instructor manages two dives on one 12. FML
Thats one of the ,,hardest" theme. Sub ( a big national agency) says use 25 Liter p.m. for diving ssi says use 15. ( of course for underwater) Back when i made owd, that confused me a bit and even scared me a bit.
We were trained on this heavily for OWC thru my shop. I sit around 11-14L/m (calculated by my cobra) and I am still a novice diver IMHO. I do control my breathing on land so I attribute that along with just the pure love for being in the ocean.
Hmmm... so if you're accounting for the actual tank capacity wouldn't this be RMV rather than SAC? (I know, I'm splitting hairs, sorry!) My understanding was that SAC is measured in psi/min or bar/min while RMV would be cf/min or L/min. SAC is easier to calculate but you'll have a different SAC rate if you change tanks whereas RMV works across all tanks. Either way, super valuable information to have - even if it's just to measure your improvement as a recreational diver! Cheers!
Sac * tank (7, 8,5, 10, 11,1, or 12l) is your liters per minute. I have a sac from 2,0 with a 12l bottle. 2*12=24 avm so i need 24l air in the min. And this information is what i need to calculation a deko dive
Yes but sac is better for air integrated dive computers. Because the computer dont know the size of the tank. And if the user need the rmv, he know how he get it.
I was going to add to this thread, but you guys have straightened it out! I was focusing on SAC here because it's a better tool for Recreational divers to track their usage even when using different size tanks. Thanks for watching! James
I actually just sent an article on diaphragmatic breathing to SDI for their blog and in it I mention SAC rates at the end. I've also seen new tec divers doing an initial or baseline SAC calculation sitting in a classroom environment and thought while extremely boring that could serve as exactly that - a great baseline. Your thoughts??
Exactly that. At Tec levels, it's essential information for dive planning. I tell all entry level Tec students to go back through their recreational dive logs and calculate their RMV or SAC rates before starting class, so we have a baseline coming in. Then we calculate SACs for every dive on the course in Tec configuration and with the stressors of performance requirements. Thanks for watching, Roy. James
Hi Just Keep Scuba Diving! Thanks for watching. Not sure I can recommend hyperventilating as the science on that is pretty clear in regards to CO2 build up. I'd recommend sticking to long, slow, deep breaths throughout. What is causing your headaches? Is there another way to mitigate them? All the best, James
Divers Ready I think one of the things that is creating my headache, is at the 15 foot mark you can see the surface. So, I was watching that instead of actually watching my gauge coming from the 15 foot point to the surface. But now that I’ve started slowly and calmly going from the 15 foot point to the surfacemy headaches have gone away
James, can you please make a video covering tricks and tips to slow your rate of breathing while diving? I think most new divers like myself would greatly benefit from this. Thanks #askdiversready
Hi Vandoo66. In Metric, the size of the tank is measured NOT at working pressure as with imperial, but as it's empty volume. An 11ltr tank at 200bar pressure holds 2200ltr of gas. So, yes, you can breathe 1606ltrs from the cylinder and have 594ltr remaining. Thanks for watching! James
Divers Ready I’ll review it again 🧐 but I’ll obviously give you the benefit of the doubt. Thanks for the reply, good channel. Keep it up. p.s. still have a problem with the whole ewok thing.
In my experience, practice. Mastering buoyancy means less fiddling with your BCD (i.e. not using so much air doing BCD adjustments.) Getting more comfortable with diving and slowing things waaaaaayyyy down means doing things more deliberately and more efficiently (i.e. reducing your body's demand for oxygen while you dive.) Lastly, just try and be really conscious of your breathing. Imagine yourself late at night just vegging out in front of the TV - you know - that near-comatose state! Picture yourself breathing in that scenario and try and do that while you dive. "Breathe like you're sleeping" was what I was once told to do. And, unfortunately, the fact is that's now how we normally breathe so it takes a bit of practice to get into a habit of just doing that underwater! Start out breathing like that and try to realise when you go back to breathing normally - then close your eyes and visualise yourself staring half-awake at the TV again. After a bit of practice you'll be able to sustain that slow breathing for an entire dive.
Hi Tom! Thanks for watching! That video is coming! I agree with what Chris says above... get yourself into a meditative state and the more you dive, the better you will get at it. To help that process, here's a quick tip: Focus on getting your inhale and exhale equal. breathe in for a four count, and out for a four count. When you find you're doing that without actually counting to four each breath, go to five.... and so on. Dive safe. James
@@mrchriscarleton stop this is the rhythm of surface breathing. Breathing in, breathing out, break breathing in. If you breathe like on the surface you need not so much air.
My digital logbook does this for me. I download the data from my computer and plug in my starting and ending pressures and it spits out the numbers for each dive.
I downloaded a sac rate calculator and to my shock my sac rate on average was .37, I couldn't believe it so I did the math...erm...maths, and the calculator was correct. Is that a good rate for a new diver? Thanks, also James
If that .37 is cu.ft/min. it is just crazy. It is really good. Being a new diver and having that sac rate is like a blessing, enjoy it and if you can improve it even more, you’ll be limited by your ndl every single dive jajaja
@@21maruru I used metric units to do the calculation, I came up with 10.6 L per min which is actually .374 when converted so I rounded down. This is assuming that a 100cf aluminum tank is equivalent to a metric 13L tank.
@@21maruru actually I see where I messed up, I used feet for my average depth instead of meters. Actual sac is 20L per min...still not terrible but not as good as I thought 🤣
What are your thoughts on Shearwater's psi/min version of SAC rate vs the cuft/min or liters/min? Am I right in thinking as long as you dive the same tank size, psi/min will be comparable across all dives? It would be great if Shearwater gave you the ability to auto-calculate cuft or liters per minute if you enter tank size.
