SAC rate issues

[Alii994]

Hi all, I could use any advice I can get on here.

My SAC rate is terrible, I consume air quite fast and I’m not sure what I’m doing wrong.
I’ve been diving for the past 4 years, I thought I had less dives but according to my computer I have 124 dives. According to my perdix my avg SAC rate is 29 psi/min and I am consuming air worse than anyone around me.

I have good buoyancy and trim, I can always improve but I don’t think that’s the issue.

I’d like to think I’m in fairly good shape, I‘m 180cm/ 5’10 tall, I weigh around 97kg/215lbs but I honestly workout 5-6 days a week and most of that weight is muscle.
I dive without weights in saltwater and fresh water.

I would like to avoid having to purchase a set of 133 cu tanks just so I can keep up with people diving al80’s.

I am getting more into tec diving and have a class in September, I will definitely work with my instructor on it. But I’d like to keep practicing and improving until then.

If at any point I sounded arrogant in my post, please do know I do not mean to do so and I’m truly just asking for advice on here. Please let me know if there are anymore details I need to state.

 

[Brett Hatch]

Since you're talking about diving with no lead on AL80's, I assume you are talking about warm water, like in a 3mm wetsuit or maybe just shorts. 29 psi/min SAC might be on the high side for those conditions, and could be an area where you can improve with some focussed practice. But, some people's SAC is just higher than others.

I haven't dived with you, of course, but my guess would be that you move around a lot. Either swimming quickly from place to place, or just kinda frequently sculling with your hands or fins. If your impression is that you don't move much, see if you can get a friend to film you diving for a few minutes. You might just be moving a lot more than you think you are. I haven't taken a tech diving course, but it's my understanding that this is very commonly one of the first things you will do in such a course, because seeing yourself from the outside can be very illuminating.

 

[L13]

You are too big, too strong, and in too good a shape. All the muscle burns more O2, producing more CO2 that has to be removed by breathing. All that cardio means you have big lungs that go through lots of air removing that CO2.

Be happy about your health and don't worry about your SAC. Quit attaching a moral or skill value to a low SAC. Most of it is physiology that you can't do anything about.

Although @Brett Hatch is right that moving less helps (all those muscles moving less produces less CO2).

 

[Tom_Ivan]

There is no pride in a low SAC rate. If you need to carry more gas just do it.

-Poorly performing regs wont help so make sure they are in good working order.
-Learn to frog kick if you haven't already. Make sure you take a long pause between kicks to ensure you not balancing poor buoyancy by kicking upwards or downwards.
-Lace your fingers together to ensure that your not sculling with hands.
-Plan your dive if possible so that you are not moving much.
-At the beginning of each dive just take 5 minutes to chill on the bottom. Be super relaxed before moving off.
-Move slower through the water. There is a square relationship between velocity and drag in water. If you can half your speed you'll reduce to drag to 1/4


But personally, I'd just try source some bigger tanks.

 

[Edward3c]

There is one instructor I dive with who uses 15Lt cylinders, I use a 10Lt when diving with him so I'm not wasting gas and he feels more comfortable as our gauges are going down together.

Just dive with larger cylingers. Not much you can do with you're metabolism.

 

[scubaozy]

Not wearing exposure suit will increase your consumption, make sure you are comfortably warm. Athletic people are expected to use more o2, but at the same time their circulation is more efficient, so, they can exert them selves while keeping their pulse and respiration rate lower. Basically you do have still potential to improve. I have low sac rate and thanks to my descent mk2i, I recently monitor my heart rate during diving and I get up-to 10 beats less than my resting heart rate at the surface while diving with moderate activity. If you are unable to lower your heart/resp rate, you are not relaxing, you need to find the reasons that are hindering that.

 

[Alii994]

Thank you all!

Yes, I sink with one set of AL80’s on my back, and sink even more using an lp 85.

I don’t use my arms much, other than when I’m using my light to point at something, they are either hovering infront of me or resting on my shoulder straps.

My regs were serviced recently. I dove mostly with piston regs (sp mk25 g260 and aa t3). I‘m still learning more about the mechanics behind the regs, I was thinking of trying out diaphragm regs and see if that makes a difference but truthfully, I’m just playing a guessing game here, I’m not all too familiar about how piston vs diaphragm regs would affect my breathing.

I frog kick 90% of the time, times I don’t are I’m using a modified frog kick, helicopter, back kick, modified flutter because of limited spaces or flutter kicking in open water for a limited time to cut through current (When certain dives should have been drift dives to begin with, but unfortunately were not and had to make it back to the boat somehow)

It looks like I’ll have to invest in a twin set of hp 133’s to be on the conservative side. I’ve tried them out before, their weight and size don’t bother me much in open water. It’ll certainly be an adjustment from my lp 85’s, I’m still going to keep them for sidemount. But I plan on building out a different configuration for open water twin sets anyways.
If you all have any other suggestions please let me know. I’m all ears.

 

[Alii994]

Not wearing exposure suit will increase your consumption, make sure you are comfortably warm. Athletic people are expected to use more o2, but at the same time their circulation is more efficient, so, they can exert them selves while keeping their pulse and respiration rate lower. Basically you do have still potential to improve. I have low sac rate and thanks to my descent mk2i, I recently monitor my heart rate during diving and I get up-to 10 beats less than my resting heart rate at the surface while diving with moderate activity. If you are unable to lower your heart/resp rate, you are not relaxing, you need to find the reasons that are hindering that.

I never considered that. That’s a great idea! Thanks!
I don’t own an mk2i but I own an apple watch I could use for that with a chest strap to monitor it.

 

[Tom_Ivan]

Sounds like there is not a lot else to improve. Just double check your swimming speed and slow down if possible. I don't think changing regs would help.

You can use the HP133 for sidemount. Its a bit awkward at first and it'll take a few dives to work out the trim but having that much gas on a dive is awesome!

 

[BlueTrin]

Hey I have a fairly higher sac rate compared to many of my buddies. If you need to carry more gas just do that.

I think my sac rate is a bit lower since I stopped lighting heavy weights and do more HIIT.

Also when you frog kick, do you glide: I am asking because I see many people kicking non stop and you’ll get better results if you pause and glide after the kick and try to move slowly (you will not feel the need to breathe as much)

Someone on this forum showed me this video and it helped me to refine some bits (just in case it’s useful)

The Frog Kick

Every diver must master this kick, most experienced divers use it approx 80% of the time…

www.sidemounting.com