SAC Rates

[Brian Sharpe]

I was hoping this topic would already have been flogged to death but.........

What constitutes a good SAC rate?

I know there are a zillion variables involved and every diver will experience different rates on almost every dive.

When I first started diving I could suck a tank dry in no time flat, yesterday in the St. Lawrence (mid 70s water, not much current) my SAC was just under .68 and my best to date is just under .65.

At 5' 10" and 200 lbs is this about as good as gets or can I expect it to improve more over time?

 

[Blackwood]

Low enough that you can do the dives you want to do while maintaining enough gas to surface with your equipment.

 

[Brian Sharpe]

Thank you......

 

[ajduplessis]

I believe your SAC can still improve to around .50 (around 14 litres per minute) or better quite easily. That is if I did my conversion calculation correctly. My SAC was also in the high 19's (.68) when I started. This changed dramatically once my mentor pointed out too slow down all movements (workload) in the water. I also focused more on diaphragm breathing and started cardio (cycling). Some considerations that effect SAC:

• Cold water effects SAC. Do you get cold during dives, might want to add more thermal protection (hood gloves etc).
• Stress levels (depth, strong current, low vis) have huge impact on SAC, especially if you are new to these conditions
• Struggle to maintain buoyancy (over/under weighted)
• Overbreathing

 

[TSandM]

I don't know -- I think .7 is widely quoted as an average SAC rate for an adult male. Obviously, how much swimming you do on a dive will affect this a lot. My favorite dive buddy is about as quiet and efficient a diver as you could ask for, and is a very fit man, and his runs about .7.

There is little benefit and considerable risk involved in trying to reduce your SAC rate below what is comfortable and normal to keep your CO2 where it should be.

 

[Thalassamania]

When I was young and foolish I was able to drop my SAC rate well below 0.5. I got occasional headaches and such and figured that was the price to be paid. Then I learned about the increased risk of oxtox on deep dives and DCS on the long(er) dives I as trying to create, and I decided that I will make a conscious attempt to keep my SAC up at about 0.7. If I need more gas ... there's always doubles or a larger cylinder.

 

[LeadTurn_SD]

I'm a fairly "large fellow" at 6'5 / 260 lbs. My RMV ranges from .6 when I'm just "hanging out" to a little over 1.0 if I'm swimming moderately hard against surge and current.

My average on most dives falls between .7 and .8 ..... which is not significantly different from when I was in my 20's (I'm 52).

These are all just "numbers". Each of us is different. It is valuable to have a good idea of what your consumption rates are for planning purposes, but I think that setting a goal to hit some magic RMV is a mistake. Relax, enjoy the dive, and your RMV "is what it is".

BEst wishes.

 

[piikki]

Your SAC is fine. Where did you dive? Isn't the water lovely right now!
I am your height but a lotta pounds off, woman and probably have quite a lot more experience. When I dive in St Lawrence my SAC is pretty consistently around 0.6:s. Sure, if I do something like Rothesay or just drift I can drop a lot off but anything else in the river and it can easily get higher too.

There is totally unnecessary competition with these SAC numbers (that vary like you say). A lot of people quote their best numbers and cut off factors for gear, cold climate - hot weather/cold water (although it was 73F this weekend in the river), and having to fight your way down to wrecks/locks etc that gets you winded for the first half of the dive.

Worst thing is to compare and worry during dives. Yours is fine, especially if you are a guy in drysuit. Just keep an eye on that gauge during the dives and enjoy the season!

 

[Buoyant1]

Low enough that you can do the dives you want to do while maintaining enough gas to surface with your equipment.

'zactly!

 

[Brian Sharpe]

It is valuable to have a good idea of what your consumption rates are for planning purposes.............BEst wishes.

Exactly my purpose!