New Divemaster air consumption

[Alaskan Scuba Dude]

Sometimes I just cross my legs and drift in the currents or just hover in no current water. Sometimes I close my eyes and see if I can maintain depth with my eyes closed. I've been accused of taking naps on my dives lol

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Southern Mantis style diving.

 

[Alaskan Scuba Dude]

I agree instructor should wait, but this will give me the ability to dive free, make a little income at the same time. Sorry if you disagree, but it’s the best opportunity I’ve had in my life. I love people and love seeing the face on new divers, or after a new site. Just wanted some advice.

Since you already have a verbal contract to work in the dive industry I would disregard all inconclusive comments and continue forward with your training. From what you have mentioned thus far, there is no valid reason not to go from novice to Instructor. Your future employer wants confidence not doubters. If you find your air consumption has not improved once you're leading dives, sling a pony bottle, or dive doubles.

 

[Orenda]

Re: my earlier suggestion, here's the relevant math:

Start by dividing your PSI used by number of minutes. For example, if you started with 3,000 PSI and ended with 2,000, that means you used 1,000 PSI. And let's say it took you 40 minutes to breathe that much, so that's 25 PSI/minute.

If you were sitting on the couch, that's your SAC rate. If you were underwater when you breathed that 1,000 PSI in 40 minutes, you have to adjust for the depth first. Calculate absolute pressure by dividing your average depth in feet during the dive by 33 and then adding 1. (As you probably remember, every 33 feet equals one atmosphere, plus there's the real atmosphere up there.) Some computers will display your average depth; if yours doesn't, and you can't borrow one that does, see if you can download your dives to a program like Subsurface, which will calculate it for you. You could also just do a square profile dive over a flat bottom to make the average depth easier to estimate. So if your average depth was 20 feet, divide 20 by 33 and add 1 to get 1.6. Then divide your 25 PSI/min by your 1.6 absolute pressure to get a SAC of about 15.6 PSI/min.

If you used the same tank for your couch SAC measurement and your dive, you can just divide the latter by the former to get your dive factor. Let's say you had an underwater SAC rate of 30 PSI/minute, and only 15 on the couch; that gives you a dive factor of 2, and tells you that you have some room to work on your technique. But if your in-water SAC rate was 30 and your couch SAC rate was 20, your dive factor is 1.5, which is pretty good. That would mean you're just a big guy who's always going to be a bit of an air hog, so you should plan accordingly with larger tanks.

If you couldn't manage to get the same size tank for comparison, or if you want a better idea of how you stack up to others, or if you're just having so much fun with all this math, you can go one step farther and calculate your RMV. First look up or calculate the tank factor for each tank you used. Divide the rated volume of the tank by the rated pressure, e.g. for a standard AL-80, 80 ÷ 3,000 = .0267. Multiply that by your SAC rate. So if your SAC rate was 30, that works out to .8 cubic feet per minute. Most guys will be somewhere in the neighborhood of .7 cf/min, at least until they get a lot of practice. Bigger guys will breathe more, and everyone breathes more in colder water or when swimming against a current. Pro tip: don't try to compete with your lady dive buddies on this; you'll only drive yourself crazy.

As to your question about how long it'll take to improve, it really depends. But I can tell you that, during my first 50 dives, my RMV averaged around .7; by the time I got to 100, I was down around .65, and by 150 I was down to a little over .5.

Thank you, very detailed and non judgmental. Exactly the answer I was looking for.

 

[SlugLife]

I started diving less than a year ago, but I immediately fell in love with it and went all in. I’ve started my divemaster course and intend to do the IDC after 6 months as a divemaster. I’m confident and comfortable with my skills, except air consumption. I’m 6’2” 240 lbs so I suck a lot of air. 20-30 ft I average an hour but at 50 ft it’s more like 35-40 mins (with 3 min SS and coming up with 5-6 bar). Will I encounter problems as a DM? Ive never been the diver that required the group to turn around because of low air, but worried I’ll lead a dive and have to turn before a paying customer needs to. Is there anything I can do to decrease my air consumption?

For a new diver, you seem to be doing fine. Training is a great way to advance faster, but much of advancement comes from experience and time underwater. Personally, I hate the name "dive master" but I suppose training agencies have to make their money somehow.

Your air-consumption does seem on the high-side, but you're also quite new, and there are probably several things you can work on to improve air-consumption:

• Be mindful of your breathing rate. I simply mean observe it, and gain a consistent awareness of how fast you're breathing.
• Don't "skip" breaths, but you may occasionally find you're simply breathing faster than you need to occasionally. (Skipping breaths can cause a CO2 hit, which then causes you to breath more, and makes it worse)
• Mentally relaxing and confidence underwater can help quite a lot with your SAC rate. Start on the boat or shore, by NOT rushing to be the first one with their equipment on and in the water.
• Being warm underwater can help significantly with SAC rate. Being cold can cause it to increase significantly. Feel free to wear a thicker wet-suit or hood. Though don't wear one thicker than you need, as thicker wetsuits are less flexible.
• Don't start dives out of breath. For example, if you swim to a location on the surface before a dive, wait until your breathing rate comes down before starting the dive.
• When underwater and finning, take longer, slower, bigger finning-strokes. It's not a race. If you're leading a group, they're probably there to relax and enjoy anyway. I personally can go much, much farther on the same amount of air by going slow than by going fast. You also waste a lot of energy with fast/powerful finning-strokes.
• Take a steady pace when it comes to your scuba-advancement; you seem to be trying to pursue a lot in a short amount of time.
• Exercise, and being in shape can help, although there are plenty of big people with good SAC rates.
• Work on being appropriately weighted, "mastering" buoyancy, and having proper trim. That means being horizontal when underwater, and being able to maintain neutral-buoyancy or increase/decrease elevation based on lung-volume.

If all of that doesn't work, there's always bringing more air. Instead of the standard 80CU, you could upgrade to a Steel 100, or even 120. Doubles is another option. Even double 50cu will give you an extra 20cu of air. You could technically do Sidemount to (it's like doubles) but I wouldn't recommend it this early in your dive-experience. You could sling a 30, or 40cu pony-bottle as well, and get used to regulator-switching. As a bonus, you'll have a redundant air-supply.

 

[Blackcrusader]

So you pay, so you can sleep on a dive

Who says I pay for every dive I make?

 

[Blackcrusader]

He said he is currently taking the DM class, so...

Reminds me of another diver on the forum that when from OW to DM in the shortest possible time.

 

[Orenda]

For a new diver, you seem to be doing fine. Training is a great way to advance faster, but much of advancement comes from experience and time underwater. Personally, I hate the name "dive master" but I suppose training agencies have to make their money somehow.

Your air-consumption does seem on the high-side, but you're also quite new, and there are probably several things you can work on to improve air-consumption:

• Be mindful of your breathing rate. I simply mean observe it, and gain a consistent awareness of how fast you're breathing.
• Don't "skip" breaths, but you may occasionally find you're simply breathing faster than you need to occasionally. (Skipping breaths can cause a CO2 hit, which then causes you to breath more, and makes it worse)
• Mentally relaxing and confidence underwater can help quite a lot with your SAC rate. Start on the boat or shore, by NOT rushing to be the first one with their equipment on and in the water.
• Being warm underwater can help significantly with SAC rate. Being cold can cause it to increase significantly. Feel free to wear a thicker wet-suit or hood. Though don't wear one thicker than you need, as thicker wetsuits are less flexible.
• Don't start dives out of breath. For example, if you swim to a location on the surface before a dive, wait until your breathing rate comes down before starting the dive.
• When underwater and finning, take longer, slower, bigger finning-strokes. It's not a race. If you're leading a group, they're probably there to relax and enjoy anyway. I personally can go much, much farther on the same amount of air by going slow than by going fast. You also waste a lot of energy with fast/powerful finning-strokes.
• Take a steady pace when it comes to your scuba-advancement; you seem to be trying to pursue a lot in a short amount of time.
• Exercise, and being in shape can help, although there are plenty of big people with good SAC rates.
• Work on being appropriately weighted, "mastering" buoyancy, and having proper trim. That means being horizontal when underwater, and being able to maintain neutral-buoyancy or increase/decrease elevation based on lung-volume.

If all of that doesn't work, there's always bringing more air. Instead of the standard 80CU, you could upgrade to a Steel 100, or even 120. Doubles is another option. Even double 50cu will give you an extra 20cu of air. You could technically do Sidemount to (it's like doubles) but I wouldn't recommend it this early in your dive-experience. You could sling a 30, or 40cu pony-bottle as well, and get used to regulator-switching. As a bonus, you'll have a redundant air-supply.

Awesome. Thank you. I did fail to say on my shorter time dives, I brought a camera and was “chasing that grouper” etc. I also never use a wetsuit above 75. Never felt cold, but maybe it is making a difference. Appreciate the feedback

 

[Wibble]

Cameras. Evil things that are a massive distraction. Best left with other people so you can concentrate on the diving. Bit like a concert where some people's memory is from watching it through a phone screen,

When the core skills have improved then your camera footage will improve.

 

[Cthippo]

Cameras. Evil things that are a massive distraction. Best left with other people so you can concentrate on the diving. Bit like a concert where some people's memory is from watching it through a phone screen,

When the core skills have improved then your camera footage will improve.

Maybe for you, but for a lot of us the camera is the reason for the dive. For me SCUBA is a way to get close enough to something to get video of it, otherwise I wouldn't be doing it.

 

[Wibble]

Maybe for you, but for a lot of us the camera is the reason for the dive. For me SCUBA is a way to get close enough to something to get video of it, otherwise I wouldn't be doing it.

Absolutely.

Trying to make the point that my diving was worse because of the camera’s distraction. Leaving it off the dive meant my skills improved.