How Fast Do You Breathe_ Track Your SAC Rate To Maximize Your Scuba Diving Pleasure!.

Ha ha ha. Just kidding, it's empty. At last, an appropriate size of coffee. This Mouthpiece Monday, I'm drawing from my experience as a technical diving instructor to help you become a better recreational diver by tracking your sack rates. Confused? You will be. Ladies and gentlemen, what is going on? Welcome to Divers Ready. My name's James. If you're new to this channel, I make scuba diving hints and tips videos with one single goal in mind, to help make you a better diver. So if you haven't done so already, click on that subscribe button and the little bell icon, and that way you'll never miss any of our awesome content. I've said it before and I'll say it again. I'm not trying to teach anyone to scuba dive through the internet. That doesn't work, that's not a thing, and that's not what this channel is about. But that doesn't mean that I don't draw on my experience as both a diver and a technical diving instructor to make these videos for you to help you enjoy your dives more. That's the whole reason behind this channel. But what I am gonna do today is share with you an essential tool that us technical divers use that there's really no reason that recreational divers can't use as well, and that is how to measure and track your SAC rate. Now, SAC, S-A-C, stands for Surface Air Consumption, and there are many other acronyms that technical divers use. I'm not gonna go through them all here and now, but they all basically mean the same thing. How fast do you breathe? How much gas do you pass in and out of your lungs in a given amount of time, usually one minute? Later in this video, I'm gonna be showing you how to calculate and track your SAC rate with the help of my Ewok buddy. But first, let's look at the reasons why you will want to measure how fast you're breathing underwater. In the Are You Experienced video that we made, I talk about scuba diving being a really tough sport to measure because you don't score points, so it's hard to know how well you're doing. There's no way to measure your progress. But I also say in that video that breathing is one way that you can measure your performance as a scuba diver mathematically. Now, if we all adhere to the concept of the less you breathe underwater, the better a scuba diver you are, in other words, the more relaxed you are, the more in control of your breathing you are, which of course has a knock-on effect to your buoyancy and all the other core skills of scuba diving, then by counting our SAC rate and tracking it we can look for improvement. Now, as a recreational diver, if your dives are being cut short because you're running low on gas rather than being limited by your no decompression limit, then you're not getting as long a dive as you could be. If that's something that bothers you, there is something you can do about it, and that is measure how fast you're breathing and work to improve it. But how can you compare breathing rates from different dive profiles? Now, before we get into this, a quick disclaimer. You're not gonna be using breathing rates the same way that technical divers do to plan their dive. As a recreational diver, you're still gonna be diving within recreational limits, and that means you're no decompression limit and returning to the shore or your boat with the agreed upon reserve of gas in your tank. You're still gonna be making frequent checks of all your instruments and making sure that you are measuring and monitoring your gas consumption throughout the dive, as every diver does. So just so we're all agreed, I'm giving you a tracking and monitoring tool here, not a dive planning tool. So let's start with an example of one dive first. If you want to calculate how fast you breathe down your tank, the first thing you have to do is gather some data. Ewok, are you ready? Noopa, noopa. Okay, good. Can you put up metric and imperial examples, please? See how I got my finger? No, I know you use the metric system on Endor like nearly the whole rest of the galaxy, but I need an imperial demonstration. Uh, noopa, noopa. I know you've fought your whole life against imperial demonstrations, but look, just get on with it. Here's what you need to know. Number one, you need to know how big your tank is. So let's use a standard 80 cubic feet tank. Second thing that you need to know is your starting pressure. So we're gonna imagine that this is a normal tank filled to 3000 PSI or 200 bar. You're also gonna need to know your end pressure. So let's say you finish the dive with 800 PSI left in the tank, which is the equivalent of 54 bar. You also need to know your dive time. Let's hypothetically say it was a 50 minute dive. And then you need to know your average depth. So let's say it was a 50 foot, 15 meter dive, nice round numbers. Now you need to take both of those depths and convert them to atmospheres. So in this case, 2.5 atmospheres. Now, if you're logging your dives like a good diver should, either electronically with your computer or old school with a manual book and pen, you probably have most of these numbers. All you need to do now is put these numbers to work for you. So to work out your surface air consumption, which is the equivalent amount of gas you would have breathed at that rate at the surface, i.e. at one atmosphere, all you need to do is figure out how much gas you used from your tank and then divide that by the atmospheres that you dived at and the amount of minutes that you dived. And that will give you your sack rate in volume per minute. So in our example, on the Imperial side, what we're gonna do is figure out how many cubic feet one PSI is. So we do 80 cubic feet divided by 3,000 PSI. Then we're gonna multiply that by the difference between the full and empty tank, which is 2,200 PSI. And that gives us 58.6 cubic feet of gas used. So then we do 58.6 cubic feet of gas used divided by 50 minutes, gives us our cubic feet per minute at depth, which is 1.17 cubic feet. You take 1.17 cubic feet per minute, divide that by the 2.5 atmospheres you were at, brings the total back to the surface and gives you a sack rate of 0.469 cubic feet at the surface. For the metric calculation, all you need to do is subtract your end bar from your starting bar. So we're taking 54 away from 200. That means we used 146 bar of gas. So then we need to multiply that 146 bar by the size of our cylinders, in this case, 11 litres. And that gives us 1,606 litres of gas used. And then as before, we need to divide by the minutes, 50 and the depth, 2.5. And that gives us a total of 12.84 litres per minute. Thank you, Mr. Ewok. Great job. Okay, so we've got our hypothetical sack rates here for the diver of 0.469 cubic feet or 14 litres per minute. At the surface. Now, the reason we bring those calculations up to the surface, we don't give it for the 15 metres or 50 foot depth that our diver was actually at, is because the pressure at the surface is roughly constant, one atmosphere. This means that for every dive we do at different depths, if we bring that number back up to the surface, we can compare it against other dives of different profiles. And once we've done that calculation for multiple different dives in different conditions, then we can start to look at trends. Now, there is a slight trick in the title of this video because it says how to calculate your sack rate or whatever part of this video, I haven't quite decided yet, but still. And the honest truth is that no diver has one sack rate. It is better to say that every diver doesn't have one sack rate, they have a range of sack rates based on the conditions of the dive and the conditions of the diver. There are lots of factors that influence how fast you breathe underwater, be those psychological stressors or environmental conditions or your physical condition on the dive. And these change from dive to dive. Even if you did two dives back to back on the same day at the same spot to the same depth and the same conditions, I would still expect your sack rate to be higher for the second dive than the first dive because you should be more tired on the second dive having done the first already unless you took a nap on your surface interval. God, I love naps on surface intervals. You get my point. Lots of factors influence how fast you breathe. So that means for you, the important thing to do is track all of your sack rates across all of your dives and note down the supplemental conditions. Things like, did you get a good night's sleep before the dive? Were you tired? Have you been ill recently? Is this a dive you're completely comfortable and familiar with? Or is it something new to you that adds that little psychological stressor in? Are you trying out new equipment? Are you in the familiar setup that you always dive? All of these little things are gonna tell you how difficult the dive was. You can even give the dive a difficulty rating and cross-reference that against the sack rate. Then what you wanna do is over time look to bring those numbers down. The lower your sack rate, the slower your breathing. So James, how do I slow my breathing down? How do I use less gas when I dive? Well, that, my friends, is a whole nother video. Listen, I'm a nerd. I love statistics. If that helps me enjoy longer dives, even better. Don't forget to make your next dive on that subscribe button, ladies and gentlemen. Click the little bell icon so you never miss any of our content. And if you enjoyed this content, ladies and gentlemen, I'm gonna put a link here to our other Mouthpiece Mondays and just below it, a link to our Grand Cayman playlist. Thank you so much for watching. My name's James. Until next time, this was your Divers Ready Mouthpiece Monday for this week. Dive safe, dive often.