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BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
02-14-2008, 15:50
I noticed that when I started diving dry my SAC rate shot *way* up. It's still high but its finally starting to settle back down. Have others had the same experience? If so, how long did it take to get back to normal?

# Site Depth Temp Vis BCD SAC
1 Quarry 58 55 15 TP 1.02 cf/min
2 Quarry 49 55 15 TP 1.35 cf/min*
3 Quarry 48 57 15 TP 1.23 cf/min*
4 Quarry 31 55 15 JKT 1.01 cf/min
5 Quarry 54 52 15 TP 1.19 cf/min
6 Quarry 49 50 15 BPW 0.93 cf/min
7 Quarry 31 50 15 BPW 0.91 cf/min
8 Ocean 77 57 30 BPW 0.91 cf/min
9 Ocean 81 57 40 BPW 0.86 cf/min
10 Quarry 58 48 15 BPW 0.65 cf/min

* = very serious buoyancy problems to the point of wanting to call the dive.

BCD: TP = Transpac w/Rec wing
JKT = borrowed seaquest jacket
BPW = SS BP with 30# Mach V wing

Max depth shown, SAC based on average depth according to my computer and includes gas used to inflate wing and drysuit so shorter dives should show a higher SAC rate

Charles R
02-14-2008, 16:20
I noticed that when you switched to BP/W your SAC dropped quite a bit maybe the problem was the changing of BCD's also a way to see if it is your breathing or your dry suit but a pony bottle or argon bottle hooked only to your dry suit and see how your SAC comes out this will identify if you are using more air for your dry suit or your actually breathing differently. I started out with an Argon Bottle with my dry suit and except for the first few dives getting acclimated my SAC did not change at all. Just my 2 p.s.i.

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
02-14-2008, 16:48
I noticed that when you switched to BP/W your SAC dropped quite a bit maybe the problem was the changing of BCD's also a way to see if it is your breathing or your dry suit but a pony bottle or argon bottle hooked only to your dry suit and see how your SAC comes out this will identify if you are using more air for your dry suit or your actually breathing differently. I started out with an Argon Bottle with my dry suit and except for the first few dives getting acclimated my SAC did not change at all. Just my 2 p.s.i.


I also noticed the drop when I switched to the BP/W. Coincidence or better streamlining?

I'll try the pony bottle for DS inflation to see how that affects things.

I think it's probably a buoyancy issue. The only goal for the last dive was to get the buoyancy right and keep it right. I thought I'd been hitting my BC and DS buttons too much and thus wasting my gas. Focusing on that brought it down quite a bit.

MSilvia
02-14-2008, 17:15
Out of curiosity, are you breathing out of the same air supply you use to fill the suit? If so, you might find that that's adding significantly to the gas you're removing from your tank on a given dive.

texdiveguy
02-14-2008, 17:26
Looks like you are getting a handle on the ds diving....just a learning curve,, and it appears you are doing pretty well from your progress list of dives.

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
02-14-2008, 21:54
Out of curiosity, are you breathing out of the same air supply you use to fill the suit? If so, you might find that that's adding significantly to the gas you're removing from your tank on a given dive.

Yes, so far I've been inflating the suit with back gas which is probably a reason for the higher SAC I'm seeing with the drysuit.

cummings66
02-14-2008, 22:26
I wonder how much though, I've watched the SPG when I've inflated it as deep as 140 feet and it doesn't seem to be more than a flicker. Not enough that I could really measure it easily.

I know it happens with drysuits, and it happens when you move to doubles. The prevailing theory I've heard is it's not as streamlined, but I'm not sure that's right either.

For what ever reasons, it happens and that's about it.

CompuDude
02-15-2008, 04:12
Depending on how cold the waters you are diving in, a drysuit can actually help your consumption, since you are more relaxed and less tense when you're not as cold.

First you have to get more comfortable, though, and get drysuit zen flowing. :)

Hollywood703
02-17-2008, 08:54
Also, Make short puffs of air to equalize.....Even at 130 ft I have not noticed much difference in SAC, OTHER than the fact that you feel a squeeze on occasion which could cause you to breath a bit harder. as you learn to equalize before the squeeze you should notice that your breathing ease is better as well. also you will notice you arent Inflating/deflating the drysuit as much

cummings66
02-17-2008, 09:51
Depending on the inflator valve you need longer or shorter bursts. My Viking Sport inflator is very fast, a stab at it results in a lot of air where at stab on my Viking Extreme inflator is slow. In fact on it you can press and hold for a bit without problems. I think one is SITech and the other is Apeks? They are different is all I know for sure and one drysuit is put up and the other is being cleaned from yesterdays ICE dive.

scubamarc
02-22-2008, 09:39
how can you calc sac rate while using your drysuit using the same gas? Impossible.

berick
02-22-2008, 10:36
how can you calc sac rate while using your drysuit using the same gas? Impossible.

Not really, just depends on your definition of consumption. If you define putting air into your drysuit as consumption(which it is), then you can easily calculate a surface equivalent.

CompuDude
02-22-2008, 13:46
how can you calc sac rate while using your drysuit using the same gas? Impossible.

Not really, just depends on your definition of consumption. If you define putting air into your drysuit as consumption(which it is), then you can easily calculate a surface equivalent.

Not only that, but honestly, it doesn't use all that much. Consider how many dives a 6cf argon tank generally lasts before needing a refill, and you'll see that we're only talking about a few cf of gas. Not enough to seriously affect the calculations... and if anything, it just makes you more conservative.

scubamarc
02-22-2008, 13:48
you are right, I was thinking the inflation of the suit does not count on what I breath, but that does not matter. it is how much air i need overall.

cummings66
02-22-2008, 17:44
You really don't use much air at all in a drysuit so you can ignore it for the most part, it's not enough to make you run out of air on a dive. If it did you shouldn't have been cutting it that close anyhow.

texdiveguy
02-22-2008, 17:47
Just calculate the same way you have been diving wet. You will be close enough!

BouzoukiJoe A.K.A. wrecker130 AKA Chuck Norris AKA joeforbroke (banned)
02-25-2008, 16:55
It's hard to know how much I was wasting for drysuit (and wing) inflation or how much extra I was breathing because I was improperly weighted, or cold or not adjusting the squeeze properly, or not being neutral, or not having good trim.

It was probably a combination of all of them. I have since seen on a video of dry dives 8 and 9 that I was finning instead of hovering while I was waiting for my buddy to exit the wreck. There wasn't any current so I must have been negative and compensating with my fins.

Anyway I can live with 0.65 diving in cold murky water. Since I'm usually diving a 120cf I'm sure I'll be ready to surface before I run out of air.