Techniques to improve my SAC rate

[Rudebob]

As a relatively new diver I want to improve my SAC rate. Without consideration of external factors such as temperature, currents, etc., what skills/techniques are most effective to maximize efficiency? If you were to pick only one area to concentrate on what would it be:

Breathing technique

Increase level of physical fitness (primarily respiratory)

Mental approach (overcoming anxiety, excitability etc.)

Swimming efficiency to minimize drag (technique and/or equipment selection)

Other


Thanks,

bob

 

[fisherdvm]

I think trim and buoyancy is critical, and can be corrected quickly. With buoyancy, perfect weighting is needed. Done with 500 psi and a "just dove" gears. Trim should be so that you are nearly horizontal with little kicking or effort. The weight should be distributed higher on the back. The use of trim weight on the tank strap or a steel back plate is helpful. Back inflate BC tends to trim better than jacket type.

The rest of it comes with practice and exercise.

 

[ClayJar]

Breathing technique

Absolutely not! Breathing is almost always the *result*, not the *cause*, and working on breathing instead of dealing with the root cause is likely to give you a headache (literally). :biggrin: (Hyperventilation is a cause and result, but I assume you're not panting like a tired, hot dog, eh? ) Okay, back to the question...


In *every* case with which I have been directly involved, air consumption changed most dramatically when the diver achieved proper trim. Obviously, overall weighting is part of it, but looking just at the calculated SACs in my log book and theirs, *every* diver has shown a pronounced step-change decrease in air consumption when they trimmed out properly (invariably by moving weight up toward their shoulders in one way or another).

In my case, it was a 20-25% drop from before I trimmed out to afterward. I had a given average SAC for a given selection of dives, and then I bought an extra cam band, moved four pounds from my weight belt to the cam band, and strapped it right at the shoulder of my tank. The very next dive showed the marked improvement in my SAC, and that improvement remained from that point onward. Before trim, I was at one plateau; after trim, I was simply at another plateau.

While my sample size is necessarily small (as it is limited to those divers with whom I dive often enough to directly affect their choices), in *every* case there has been a marked improvement in air consumption.

Although I have a longer, more verbose explanation, the crux of the matter is this: When you're not horizontally trimmed, you are "swimming uphill" the entire dive. (It's simple geometry. :biggrin If you're staying at one depth while moving forward, you're doing it by being negative enough to hold yourself down as you swim uphill. Once you're horizontal, your finning isn't holding anything up, so you're not doing all that exercise for nothing (think treading water while holding weight vs. floating, and consider which makes you breathe harder).

 

[SparticleBrane]

Stop waving your arms around.

 

[Charlie99]

Learn how to do NOTHING!

Being able to stop finning and stay where you are leads to a much more relaxed, lower effort, and therefore lower air consumption dive.

Learn how to keep your BCD inflation adjusted so that you can maintain depth by altering your breathing pattern a bit. Having the right weighting makes this easier. Using a frog kick, with the glide period where you can check your buoyancy is a bit easier than the flutter kick, which can mask a lot of buoyancy problems. With a flutter kick, you need to stop finning for a while every now and then to check your buoyancy.

The advice by Clayjar of "learn proper trim" is along the same line. Not having good trim means you are finning upwards (or more rarely, downwards) and you need to be negatively buoyant to compensate.

It really all boils down to learning how to do NOTHING AT ALL. No arms flailing. No continuous finning to maintain depth.

Also, remember that it isn't a race down there. Outside of coral and sea cucumbers, there aren't a lot of things down there that can't easily outrun you. Let the sea life come to you. Learn to slow down. Reduced air consumption is the result of exerting yourself less.

Charlie Allen

 

[bubba105]

What they said plus gaining comfortability underwater. We had a girl on a recent trip to Cozumel who, after her check out dives, never brought a tank back to the boat with less than 2000psi, on any dive. She was a competitive sychronized swimmer who was exceptionally comfortable in the water. Trim & buoyancy were in the toilet but she breathed like she was napping. Comfortability comes, for most of us, with more dives as trim & buoyancy become more natural. Just keep diving, everything will fall into place. And yes, as sparticle said, try not to wave your arms.

 

[emttim]

What they said plus gaining comfortability underwater. We had a girl on a recent trip to Cozumel who, after her check out dives, never brought a tank back to the boat with less than 2000psi, on any dive. She was a competitive sychronized swimmer who was exceptionally comfortable in the water. Trim & buoyancy were in the toilet but she breathed like she was napping. Comfortability comes, for most of us, with more dives as trim & buoyancy become more natural. Just keep diving, everything will fall into place. And yes, as sparticle said, try not to wave your arms.

I wonder though if her excellent air consumption was not completely the result of being comfortable in the water...if she's a competitive swimmer, then I would imagine she is in extremely good physical condition, and the more in shape you are then the less panting and air sucking you're going to do as you get tired (and it'll take more muscle exertion to start to get tired), so that probably was a contributing factor as well.

I'll have to check my trim on my next dive since I'm definitely looking to improve my air consumption as well. Although I will comment that it's easier said than done to stay in one spot (not at same depth but in same specific spot) when there's surge or current...sometimes you can't help but have to fin or scull to get to where you want to be, especially if you just want to re-orient the front part of your body to get in a better position to look at something. Most of the times I sculled on my last dive trip wasn't because I needed to in order to stay at the same depth or whatnot, but because I wanted to stay horizontal and/or I wasn't quite at the angle I wanted to be to look at something. Although the horizontal thing may be tied to trim so I'll have to look into that.

I dunno, I'm definitely going to work on the fitness thing; I wouldn't be surprised if a high level of physical fitness was a significant way of decreasing air consumption.

 

[Firefyter]

Learn how to do NOTHING!

This is almost exactly the advice I give new divers... "Learn to be still." It was the key to fine tuning my trim and really, really learning buoyancy.

 

[redacted]

Learn how to do NOTHING!

It really all boils down to learning how to do NOTHING AT ALL. No arms flailing. No continuous finning to maintain depth.

And the way you master skills in scuba is PRACTICE. Spend some time, maybe even most of some dives practicing doing nothing. Focus on chilling out and not exerting any effort.

Then try to approach that state when you are actively diving. Examine the things you are doing that take you away from that state and think about how to reduce or even eliminate those things.

It took me from a SAC of well over 1.0 to a SAC of under .5. If I really focus on not working, I can get it down close to .4.

 

[String]

Techniques to improve SAC

(i) Get your weight correct
(ii) Get the hang of buoyancy control

(iii) Most important of all - dive LOTS

Thats all you need. Fitness wont have as much of an effect as the above so just go diving as much as possible. Oh and stop worrying about SAC as the more you worry the higher it'll be.