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Heavy Breathers - What's your SAC?

  • None - I have gills

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"Three sheds"
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When I started diving I was a VERY heavy breather. Looking back through my log books, although my SAC has fallen significantly, it still quite high. My lowest SAC last year was 22 litres / min. The highest was around 27 l/m.

So am I freak of nature? Or are there any other heavy breathers out there.

Laters,
   Janos

PS -  I've been diving for about 4 years, but only started diving in the UK 2 years ago. I've done about 150 dives, of which about 70 were in the UK. Although I hope my SAC will continue to drop I think it's pretty much bottomed out.
 

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old time
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<font color='#0000FF'>When i first started it was 15- 20, but now after 20 years of smoking , i've got it around to 8,,,,,,,

I do all my scuba dives planned on 8

But being a commie for years ,,, i got used to sucking air as it's unlimited
 

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Its up and down like a yoyo. Some days I get about 11-12 other days 18-19 I think the average is about 14.
 

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Liberal Lefty
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When I started diving my SAC was around 25.ltr a minute.  It's come down gradually as I've done more diving and sits around 18ltr / min depnding on the dive - more for cold & exercise, less when warm water diving.  Fitness level affects your SAC as does smoking  -if you smoke cut down, and if you don't already, try jogging or other aerobic exercise.  You're SAC should drop noticably
 

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Just not enough dive time.
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Mine has always been around 25 and that's what I plan for, according to BSAC that is a good average for a diver doing moderate excercise. It has stayed there virtually since I started diving. I think part of the reason is that its actually come down since I startred in a wet suit and single but I now use a dry suit, single & pony (back mounted) torch and dsmb on every dive which has increased my drag factor bringing the sac back up in effect to 25. When I get my new twins it WILL drop to a very much lower level, yeah right.

Matt
 

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Hi Janos,
Your not the only one, im a very heavy breather
,have to keep a eye on my guages ;)
dont know how to work it out, but have done once used my 15 ltr 235 bar almost sucked it dry in less than 15 min at 20 meters ish

Have been told it il get better, but cant see that happening

Tony
 

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[b said:
Quote[/b] ]Have been told it il get better, but cant see that happening
You'd be surprised mate - dunno if you've been on a dive hol yet, but a week or two of solid diving will work wonders on your SAC.

Why isn't there an option on the poll for ....Got a breather, don't bloody care?
 

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[b said:
Quote[/b] (Rob Evans @ Feb. 01 2004,18:19)]
[b said:
Quote[/b] ]Have been told it il get better, but cant see that happening
You'd be surprised mate - dunno if you've been on a dive hol yet, but a week or two of solid diving will work wonders on your SAC.

Why isn't there an option on the poll for ....Got a breather, don't bloody care?
yep been on a diving holiday, was suposed to be a week 20 dives max, but boat sank on 2nd/3rd day
, never go back there again  

Tony
 

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My lowest ever SAC was on my 6th dive (12.2)! Being sat stationary at 5.5M for over an hour waiting to do the navigation part of my AOW I think had a significant effect!

Normally in the UK (first 17 dives) my typical SAC is around 20. It does very quite a bit depending on how energetic I am underwater.

I recently went to Sharm and did 12 dives over there over 5 days and the SAC was consistantly 15 +-0.5. Doing lots of gentle consequative dives in warm water helped.

From what guides have said I think my SAC is quite good considering the dives I have done. Should still come down furthur though.
 

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<font color='#0000FF'>
[b said:
Quote[/b] (Col.Maniac @ Feb. 01 2004,18:16)]Hi Janos,
Your not the only one, im a very heavy breather
,have to keep a eye on my guages ;)
dont know how to work it out, but have done once used my 15 ltr 235 bar almost sucked it dry in less than 15 min at 20 meters ish

Have been told it il get better, but cant see that happening

Tony
Tony, an easy way to work it out is by starting with your average depth, usually on your computer somewhere.
Then minus your BARout from your BARin, divide the figure by your Dive time and multiply by absolute pressure of your average depth.

Ie, Average depth = 15m
    Bar in = 230
    Bar out = 50
    Dive time = 30 min

so, 230-50=180.
    180/30 = 6
    6 x 2.5([email protected]) = 15 litres per min.

Not exact but close as most of us need.

HTH, Stu.
 

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Just not enough dive time.
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Stu where do you use the size of the tank in your example above?

I reckon its (235 - 50) x 15 = 2775ltrs
2775/30 (dive time)           = 92.5l/min
92.5 / Av depth Bar           = 92.5/2.5 (for 15m)
                                    = 37l/m sac

By my calcs.

Regards
Matt
 

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I voted 20-25, which I guess is about average.  I checked my recent dive on the Thistlegorm, where I felt really relaxed, correctly weighted and didn't think about my breathing at all and it was 17!

It's hard to check my recent home waters SAC, since everytime I get 10 mins and 20m into the dive, my sodding regs freeflow
 Think they are going back to the manufacturer...

dan.
 

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To dive or not to dive - that's not even an option
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[b said:
Quote[/b] (PressurE @ Feb. 01 2004,18:53)]Tony, an easy way to work it out is by starting with your average depth, usually on your computer somewhere.
Then minus your BARout from your BARin, divide the figure by your Dive time and multiply by absolute pressure of your average depth.

Ie, Average depth = 15m
    Bar in = 230
    Bar out = 50
    Dive time = 30 min

so, 230-50=180.
    180/30 = 6
    6 x 2.5([email protected]) = 15 litres per min.

Not exact but close as most of us need.

HTH, Stu.
Don't use this formula, it's wrong, and you will run out of air big time! If this is on a 12L cylinder it equates to around 180L/min!!, now that IS heavy.

Matts calcs are right in my book.

Anyway, if you are weighted correctly and your bouyancy and technique are good, you could half your air consumption in a couple of dives. Divers are too quick to blame "external" forces rather than admit they may need a bit of polishing in the skills dept. I know this is not always the cae, and don't meen to offend, but I have seen this first hand as an instructor and I am sure others have too.

Last time I dived with Billy the kangaroo I done 2 x 50min dives in 4 degrees at around an average depth of 13m and swam the entire length of Capernwray (twice) on one 12L fill, I then finished the tank on pool training.

Come to think of it, I often come out with more than I go in with??

James
 

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Team Starburst
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<font color='#736AFF'>I now use an air integrated dive computer (vytec) and this assists me to monitor my air during a dive. I am convinced that his relaxes me more and I can regularly achieve over 70 mins at 15m on one 15 ltr cylinder.

E.g. Yesterday we did two dives of 28 and 33 min at 20 and 18m in 4c of water. All on one 15 ltr cylinder. Plus I was clearing my mask for half of the first dive.

OK I will not win prizes for minimal air consumption, but it seems to improve with every dive.

I know it does, I have been sad enough to graph the info over a period of time.

As stated above, check your weight, improve your bouyancy skills, stop smoking, take regular aerobic exercise and do lots of diving.
 

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<font color='#0000FF'>Quite right Matt, my mistake.
ho humm.. dont know why I forgot cyl capacity.

keep my gob shut next time.

stu.
 

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"Three sheds"
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Discussion Starter · #18 ·
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[b said:
Quote[/b] (Rob Evans @ Feb. 01 2004,18:19)]Why isn't there an option on the poll for ....Got a breather, don't bloody care?
Double git. I'm saving ok? (About three years away now...
 

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[b said:
Quote[/b] (narkedat50 @ Feb. 01 2004,21:02)]
[b said:
Quote[/b] (PressurE @ Feb. 01 2004,18:53)]Tony, an easy way to work it out is by starting with your average depth, usually on your computer somewhere.
Then minus your BARout from your BARin, divide the figure by your Dive time and multiply by absolute pressure of your average depth.

Ie, Average depth = 15m
    Bar in = 230
    Bar out = 50
    Dive time = 30 min

so, 230-50=180.
    180/30 = 6
    6 x 2.5([email protected]) = 15 litres per min.

Not exact but close as most of us need.

HTH, Stu.
Don't use this formula, it's wrong, and you will run out of air big time! If this is on a 12L cylinder it equates to around 180L/min!!, now that IS heavy.

Matts calcs are right in my book.

Anyway, if you are weighted correctly and your bouyancy and technique are good, you could half your air consumption in a couple of dives. Divers are too quick to blame "external" forces rather than admit they may need a bit of polishing in the skills dept. I know this is not always the cae, and don't meen to offend, but I have seen this first hand as an instructor and I am sure others have too.

Last time I dived with Billy the kangaroo I done 2 x 50min dives in 4 degrees at around an average depth of 13m and swam the entire length of Capernwray (twice) on one 12L fill, I then finished the tank on pool training.

Come to think of it, I often come out with more than I go in with??

James
Thanks, any one got the right mathmatical soulution?

Im doing every thing right weight, streamlining etc,
out of the odd 44 dives I have done so far my air consumption is rather eratic, I dont over push my self and most of the time im relaxed I am generaly fit, most of the time breating of my DV my brain is telling me its not getting enough air  
so I suck on it harder  
, I tried forceably slowing my breating rate down but get that air starvation feeling
. Its not a major problem just a little anoying I have to cut a dive short because of low air.
Tony
 

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"Three sheds"
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[b said:
Quote[/b] (IDH @ Feb. 01 2004,21:20)]check your weight, .
Yup - Did a proper weight check in Stoney when I went on to twins.

[b said:
Quote[/b] (IDH @ Feb. 01 2004,21:20)] improve your bouyancy skills.
Buoyancy is pretty good, (although there's always room for improvement)

[b said:
Quote[/b] (IDH @ Feb. 01 2004,21:20)]  stop smoking
Havne't smoked for two years.

[b said:
Quote[/b] (IDH @ Feb. 01 2004,21:20)]  take regular aerobic exercise
Bugger.

Seriously though - my air consumption has dropped dramatically over the past two years. Even at the end of a week in the red sea trip is still generally 22 to 25m/l. I reckon I may get it down to 20l/min in a year or two if I keep diving lots, but doubt it will go below that.

I'm not too concerned (I'm a big lad and have recently moved to twin 12s) but just curious about what is normal.

Laters,
  Janos
 
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