How to reduce a monstrous SAC

[drrich2]

Off topic, but I really don't get why the US sticks with Imperial.

Easy for math, but not familiarity for those with a lifetime of imperial use & a great comfort level with it, for whom there is no perceived personal advantage of bothering with a new system. It's analogous to someone doing a study & claiming Spanish is easier to learn & more efficient than English (I'm making that up), and that the U.S. should covert to the Spanish language. Even if the study were right, nothing doing.

Back in college, I had a lot of exposure to the metric system. Got fluent with it for the things we used often. In chemistry classes converting units is a big part of the work. But I was fluent with it for class purposes, on paper.

Today, if you tell me you weigh 100 kg, that means nothing much to me until I mentally figure 1 kg = ~ 2.2 lbs, so you're about 220 lbs. If you say you live 15 km from me, that's useless till I figure 1 km = ~ 0.6 miles, so it's about 9 miles. And your height in centimeters is useless unless I divide by 30 to get it in feet. And we don't commonly use metric units similar to feet; people giving lengths usually go with cm or meters.

The large majority of the U.S. adult population don't do a lot of conversions (e.g.: Solution A has 50 mg NaCl/1 Liter. Convert to grams/mL). They do, on the other hand, relate height/length in feet, volume in pints, quarts & gallons, and mass (at Earth gravity) in pounds. They're already fluent with it and it works for them.

The average Joe sees no point in bothering to, over years, develop fluency with the metric system instead. And much of the argument for metric (simplifies conversions & other calculations, 'the rest of the world is doing it,' etc...) don't mean much to that average Joe.

Richard.

 

[GrumpyOldGuy]

Off topic, but I really don't get why the US sticks with Imperial. The Metric system is so easy to calculate mentally, and virtually everthing is related - distance, volume, mass, time, pressure and temperature - all in nice multiples of 10. And all very relevant to diving calculations.

The multiples of 10 idea is a nice feature for the 20th century, I am not so sure about its importance now with everything computerized. The relation ships between distance, volume, mass, etc... are cute but for the typical person they have always been almost meaningless anyway.

Anyway, its pretty typical for US corporations to force the use of the metric system now as globalization becomes a requirement for survival. Metric prints, metric fasteners, etc... The power of corporate greed may yet prevail and force the metric system on the masses.

 

[Ulfhedinn]

I purchased a 130 and never looked back. 2 dives with my 130 compared to my dive buddies AL80. I also dont notice the weight differnace.

 

[markmud]

Hello OP,

I am not an expert diver by any means; I am still training to become a good diver. My answer is a collective "all of the above" as most of the posters have some real good advice.

I have never used an exhorbitant amount of air. But, I have had to breath carefully and emulate the experienced divers I am with. They don't breath often, and they don't breath much. They are trimmed correctly, neutrally bouyant, and very relaxed.

I waste lots of gas clearing my ears. During the remainder of the dive, I don't use much air. I do have crappy ears; nothwithstanding that issue, I have always been the person who comes aboard the boat with more gas than most-- sometimes my gas consumption is "almost" as good as the divemasters I am swimming with.

Now I would like to vent. The dive industry has made a collective decision that a AL80 (77 cft) tanks are adequate for all recreational diving. I am not a 5' 4", 120 lb. women with small lungs. I am a "little" bigger than that. I do fine with an AL80, but sometimes I don't want to breath "carefully" for an hour. 80 cft tanks suck. Why is a large male with large lungs condemned for needing something more than the "industry standard" tank?

I like HP 100s. They are the perfect size for me. I always have a healthy reserve and can breath conservatively, but normally. Also, HP 100s are smaller that AL80s in physical size (less drag).

Good posts on this thread: #42, #44, #47, #56, #57.

markm

 

[Bombay High]

but sometimes I don't want to breath "carefully" for an hour. 80 cft tanks suck. Why is a large male with large lungs condemned for needing something more than the "industry standard" tank?


markm

Who is doing the condemning ? And why do you care ?

Do your own thing ... I am not a Zen diver. Never will be. I just carry more gas ... to hell with what anyone else thinks.

 

[Diogenesdemar]

Learn to meditate or start yoga. If you really want to improve your SAC you will have to give this a go. Swimming also helps but the main thing is that you need to learn to slow down your breathing rate and still fell comfortable.

I use a simple slow and deep 6 second inhale, a 2 second pause and slow and deep 4 second exhale as a breathing base. This gives me 4 effortless breaths a min and a low sac without getting headaches or retaining co2. Even 3 breaths are easy to maintain if you don't have workload like on a drift dive. Practise

Fantastic advice. The OP, and anyone else who wishes to make dramatic, lasting improvements in SAC, need to re-read and heed this.

I'm the least new-agey, touchy-feely guy you'll ever meet -- but, as soon as I got over my hang ups about giving Yoga and deep rhythmic breathing exercises a try I saw immediate improvement in my SAC. And, no, I'm not some overweight, out-of-shape, easily-winded, middle-aged chub who couldn't last 20 minutes on a tank before I started -- I will cop to being middle-aged, but I am and have been a competition swimmer for years. I wanted to improve the amount of time I could get out of every tank I was paying for . . . I just figured that 90 minutes on a tank would be better than 60.

The best thing about this? It doesn't have to cost you anything (if you're really cheap, like me, you'll begin by checking out a book from the library). Regardless of what gear you have (or purchase), or how it's configured, Yoga and deep rhythmic breathing exercises will help you more than anything else you ever try -- you have my guarantee, . . . or double your money back.

 

[elan]

Use the right tools for the job.
Need a bigger tank get a bigger tank and dive

 

[Kevrumbo]

I wish the US would go metric. Remember Jimmy Carter? Even the UK it seems has passed on the Imperial system.

Off topic, but I really don't get why the US sticks with Imperial. The Metric system is so easy to calculate mentally, and virtually everthing is related - distance, volume, mass, time, pressure and temperature - all in nice multiples of 10. And all very relevant to diving calculations.

Easy for math, but not familiarity for those with a lifetime of imperial use & a great comfort level with it, for whom there is no perceived personal advantage of bothering with a new system. It's analogous to someone doing a study & claiming Spanish is easier to learn & more efficient than English (I'm making that up), and that the U.S. should covert to the Spanish language. Even if the study were right, nothing doing.

Back in college, I had a lot of exposure to the metric system. Got fluent with it for the things we used often. In chemistry classes converting units is a big part of the work. But I was fluent with it for class purposes, on paper.

Today, if you tell me you weigh 100 kg, that means nothing much to me until I mentally figure 1 kg = ~ 2.2 lbs, so you're about 220 lbs. If you say you live 15 km from me, that's useless till I figure 1 km = ~ 0.6 miles, so it's about 9 miles. And your height in centimeters is useless unless I divide by 30 to get it in feet. And we don't commonly use metric units similar to feet; people giving lengths usually go with cm or meters.

The large majority of the U.S. adult population don't do a lot of conversions (e.g.: Solution A has 50 mg NaCl/1 Liter. Convert to grams/mL). They do, on the other hand, relate height/length in feet, volume in pints, quarts & gallons, and mass (at Earth gravity) in pounds. They're already fluent with it and it works for them.

The average Joe sees no point in bothering to, over years, develop fluency with the metric system instead. And much of the argument for metric (simplifies conversions & other calculations, 'the rest of the world is doing it,' etc...) don't mean much to that average Joe.

Richard.

The multiples of 10 idea is a nice feature for the 20th century, I am not so sure about its importance now with everything computerized. The relation ships between distance, volume, mass, etc... are cute but for the typical person they have always been almost meaningless anyway.

Anyway, its pretty typical for US corporations to force the use of the metric system now as globalization becomes a requirement for survival. Metric prints, metric fasteners, etc... The power of corporate greed may yet prevail and force the metric system on the masses.

The OP quoted a SCR that was right around my cold water rate in metric; I do most of my tech/wreck diving in the Indo-Pacific Region, so I'm always diving with Asian or European Buddies and it's extremely vital to be comfortable & fluent in using the metric system; and lastly my pressure SCR (Surface Consumption Rate) in metric is 1 bar/min using double 11L AL80 tanks --how hard is a value of "1" to use??? I would rather use a value of 1 bar/min than 14.5 psi/min in Imperial US Units to calculate gas management requirements both pre-dive and on-the-fly.

All the info I need on-the-fly is my depth in ATA (divide metric depth by 10 and add 1), my elapsed time at that depth (typically 10min intervals), and I instantly know how much breathing gas I've used in that time frame even before looking at my SPG.

 

[PhuketPaul]

I feel the most important factors in getting a lower SAC are getting the correct weighting and relaxing (going slow and not worrying about your air consumption).

I average a SAC of about 0.3 in normal recreational diving (teaching and leading dives, if I'm following someone else then it is a bit lower).
I'm 5'10" and 92kg (202lbs) and usually dive with no lead and an AL50.

I don't consciously try to reduce my air consumption, i have found in the past that when I do that then my air consumption increases, my trainee divemasters have remarked that I seem to breath very slowly, with an almost continuous stream of small bubbles - so I have measured my breathing rate and I breathe about 3 times a minute on average.

So i tell my DMTs to relax and don't worry - don't try anything specific, just reduce your weights to the minimum you need, slow down and relax and your SAC will improve of its own accord.

Paul

 

[markmud]

Who is doing the condemning ? And why do you care ?

Do your own thing ... I am not a Zen diver. Never will be. I just carry more gas ... to hell with what anyone else thinks.

Hey Bombay,

I don't dive local. I fly to places where SCUBA diving is supposed to be good. All of the dive operators I have used STRICTLY use AL80s. I do feel fortunate though as ONE DIVE OPERATOR'S CLAIM TO FAIM WAS OFFERING NEGATIVELY BOUYANT AL80s!! Woo-hoo!!!!!! Yeah, its party time .

When I have asked if larger tanks are available, they give me the "an AL80 is all you need routine", "You know, we need to get you enrolled in a couple of our classes and get you trained-up so you don't wast so much air!" "Also, if we give you a bigger tank, you will just get bent." Get bent, with a bigger tank? We are following your divemaster. You require us to follow the DM...we will get bent with a bigger tank...are you kidding!

I wish I could take my PST 100s everywhere I go, but I can't. One nice thing about SoCal diving is that you bring your own tanks.

markm