Air Breaks: When & How Long do You do Them?

[Rick Inman]

...and... my ratio changes by the deco time involved...

Will you tell us what your ratios are? (In the mean time, I'll be spending the next 3 weeks wading through all the references you gave us. Maybe I can print some out, laminate the pages and read it during my deco tomorrow. )

 

[texdiveguy]

Rick.... what is your projected profile and gases for your upcoming tomm. dive?? Alan

 

[Gene_Hobbs]

Will you tell us what your ratios are? (In the mean time, I'll be spending the next 3 weeks wading through all the references you gave us. Maybe I can print some out, laminate the pages and read it during my deco tomorrow. )

That choice depends on length of deco, number of dives in series, which dive in the series it is, how I feel after the longer break times, amount of my pure laziness creeps in, etc...

For a single dive series, I tend to be heavier on the O2 with shorter/ less breaks until the 3-4 hour deco range. After that the cough annoys me. So I started adding more breaks. Then I learned I felt better when I dropped the pO2 on the bottom. Either way, I figure a little "caver's cough" never killed anyone and I don't worry too much about perfusion on subsequent dives once that starts.

For 25 minutes, no breaks for me...

Enjoy the reading!

 

[Kevrumbo]

I would guess the dive tomorrow to be at working depth in the 57m/190' to 66m/220' range.
Range of depths & bottom times for 1:2 RD, given Rick's 25min O2 deco time:

57m 27min
60m 25min (1:2 RD setpoint)
63m 22min
66m 20min (ppO2 1.4 ata for 18/45mix)

(That's the way I would plan it. . .)

What's your planned max depth & time; bottom & deco SAC rates, Rick?

 

[Dive-aholic]

Do you switch your computer when you switch back to your travel or back gas? Otherwise your computer would be thinking that you are still on O2 and give you undeserved credit, correct?

My longest deco ever was about 25 minutes including the safety stop, so this is an interesting discussion. I have never switched back to another mix after I switched to O2.

Dive Safe!

I also plan my dives but use my computer as a back up. I switch the computer back to my main mix during the break. As for padding my stop, I always pad my stop, regardless of whether it's a 3 minute stop or a 30 minute stop.

Tomorrow's dive, I have 25 mins on O2. Would you all do an air (ok... backgas) break? Would you do the break on the 18/45, or the 50%? I know what we do... Interested in what you guys do.

I'd do the break on primary gas at about 15 minutes and pad the O2 stop with an extra 5 minutes. But I think I'm pretty conservative when it comes to stops.

 

[Rick Inman]

I would guess the dive tomorrow to be at working depth in the 57m/190' to 66m/220' range.
Range of depths & bottom times for 1:2 RD, given Rick's 25min O2 deco time:

57m 27min
60m 25min (1:2 RD setpoint)
63m 22min
66m 20min (ppO2 1.4 ata for 18/45mix)

(That's the way I would plan it. . .)

What's your planned max depth & time; bottom & deco SAC rates, Rick?

Yup. 200', 30 mins. V-Planner on the slates, and RD backup for contingencies. Bottom .8, deco .7 for the team of 3 (which is a bit more conservative than we really are). Doubles with 1 backgas 80 stage, an 80 50% deco and a 40 o2.

Oh, and scooters. My buddies have X'es, so I have to dial my souped up Mako down to six so they can keep up with me.

And, yes, we will do one backgas break of 12/6, because that's what our team has agreed to.

 

[Mike Edmonston]

Hi Rick,

20/5 is what I use and teach. Air / backgas break does not count towards deco obligation.

Safe diving

 

[grazie42]

I don´t do many of these (only done a few) but for me it´s very temperature dependent...

In warm water I´d exclude the break from the deco time but in warm water I´m less "bothered" by the O2 so don´t really need the break...I´ve done up to 30 mins in warm water on O2(without break) without any issues...so I haven´t really done any breaks in warm water and don´t see myself doing any...

In cold water I´ve felt the need for a break earlier but then I only exclude it if I´m feeling "warm" because I figure being cold is worse from a decompression POV than "staying longer"...

I´m sure that helped, not at all...