Question Shearwater Teric (GF40/85) goes into DECO on first dive (max depth 25.9m, avg depth 17.6, duration 48mins)

[Blackcrusader]

OP, the 20 & 15 values are surface consumption rates in liters per minute. If your computer is set to use feet, the equivalent is 0.7 and 0.5 cubic ft per min. The NDL planner doesn't use these, but the deco planner does. As such, the deco planner is useful for specific NDL dives, in spite of the name.

OK so like this. I use my Deco Planner to plan a dive but do not want to exceed NDL. The Deco Planner lets me know the NDL time for the gas used. So when planning make sure what gas mode the DC is in. 21% or say Nitrox 32% or even Nitrox 40% if you use that.

Don't be on a nitrox setting when you plan a dive on normal air. Easy mistake to make. Lets say I want to do a dive to take photo of a critter at 30m but do not want to go into deco. I can use the Deco Planner for this. It will show you NDL time limit.

So I take my photos and now have plenty of gas in the tank. Take an AL80 with 210 bar 11.1 x 210 gives me the liters in the tank.
let stake that at 2300 liters

Other threads tell you to to calculate gas both in metric and imperial measurements. Please read this thread. Take your time.

Al 80 vs HP100 useable amount of air

80 cf vs 100 those are the numbers but what is the difference in real life? an Al 80 holds 77 cf and I can only access 2000 of the 3000 psi, I stop at 1000 psi for safety a little more than the 600 psi stop because its harder to breath the low pressure air. So I am using 51 cf and leaving 26...

scubaboard.com

So I plan this dive for 20 minutes to 30 meters on nitrox 32%. NDL time is 24 minutes.
Great I used 805 liters. So for myself I can count around 2 bar per minute.
Now I ascend and think how much longer can I do this dive. Will I make it to an hour with say 750 psi or 50 bar left in the tank.

OK so lets say I want to end the dive with 300 liters of air. 2300 minus 805 for the first 20 minutes of my dive minus 300 liters.
So leaves me to use 1195 liters. But to play it a bit safer I say I have 1100 liters left for the rest of my multilevel dive using 2 bar per minute. Sounds all very confusing which it is so read the thread links lol

now at say my 2 bar per minute consumption rate I could do a rough calculation of the remaining dive time.

Article: Liters and Meters and Bars: OH MY!!!

You can view the page at http://www.scubaboard.com/forums/content.php?r=412-Liters-and-Meters-and-Bars-OH-MY!!!

scubaboard.com

Or I can just use my Cressi which does live real time calculation to 50 bar for me. Top right where it shows range is the time from current depth to 50 bar at current gas consumption average on the dive.

So in the screen shot I am at 17.4m depth, dive time of 54 minutes, I have 73 bar left... at top right where it says range it shows I have 11 minutes time left to 50 bar. So I easily make the 1 hour dive from the dive op and surface with 50 bar. or I could decide to ascend to 5 meters and extend the time to 50 bar by going shallow and using less air.

 

[jseyfert3]

Yes, you were almost spot on. My dive ended with Surface GF of 84.

Thank you all so much for your response. It has really broadened my understanding of GF.

Attached is my wife’s AWU dive graph (both depth and no deco graph)

I know this is a little old, but the graph of OP's wife showing the no deco graph has the no-deco line flatlining at zero. Doesn't this indicate that the OP's wife was actually, unlike originally stated, also in deco like the OP? This happens around the 40 minute mark, which is just 5 minutes after the OP went into deco.

So was OP's wife actually in deco, and neither she nor the OP understood her computer was indicating she was in deco? Or am I missing something?

EDIT: Add OP's wife's depth and no-deco time graph so people don't have to click on the link to post I quoted.

 

[scubadada]

I know this is a little old, but the graph of OP's wife showing the no deco graph has the no-deco line flatlining at zero. Doesn't this indicate that the OP's wife was actually, unlike originally stated, also in deco like the OP? This happens around the 40 minute mark, which is just 5 minutes after the OP went into deco.

So was OP's wife actually in deco, and neither she nor the OP understood her computer was indicating she was in deco? Or am I missing something?

EDIT: Add OP's wife's depth and no-deco time graph so people don't have to click on the link to post I quoted.

Hi @jseyfert3

I believe you are correct and that she was in deco at the end of the dive and until she surfaced. I would imagine the risk of DCS for this dive was not high as the GF highs were set at 85 and the husband surfaced at 84, she was probably similar.

@Divedeeplastlong was your wife locked out of her computer following the dive for missing her deco stop?

 

[Divedeeplastlong]

Hi @jseyfert3

I believe you are correct and that she was in deco at the end of the dive and until she surfaced. I would imagine the risk of DCS for this dive was not high as the GF highs were set at 85 and the husband surfaced at 84, she was probably similar.

@Divedeeplastlong was your wife locked out of her computer following the dive for missing her deco stop?

Hi both, thank you for your replies.

My wife’s AWU did not indicate deco and it was not locked out as well.

 

[jseyfert3]

Hi both, thank you for your replies.

My wife’s AWU did not indicate deco and it was not locked out as well.

Thanks. I looked up the Oceanics+ stuff a bit, it does seem pretty hard to mistake the AWU being in deco mode:
It's just odd, because the no-deco graph you posted appears to indicate she was out of NDL time and in deco.

 

[inquis]

the no-deco graph you posted appears to indicate she was out of NDL time and in deco.

From the graph you quoted, I interpret about 15 mins of NDL time remaining. I'm specifically looking at the gray trace and the right-side axis. (The yellow line/left axis seems to be depth.)

 

[mrtechbench]

Thanks. I looked up the Oceanics+ stuff a bit, it does seem pretty hard to mistake the AWU being in deco mode:
It's just odd, because the no-deco graph you posted appears to indicate she was out of NDL time and in deco.

Thanks for posting, I thought the awu just stopped working entirely if you exceeded 130ft/40m or went into deco. Is that new?

 

[jseyfert3]

From the graph you quoted, I interpret about 15 mins of NDL time remaining. I'm specifically looking at the gray trace and the right-side axis. (The yellow line/left axis seems to be depth.)

The gray trace is depth, corresponding to the left axis, see OP's post here that has another picture and makes that more clear.

Thanks for posting, I thought the awu just stopped working entirely if you exceeded 130ft/40m or went into deco. Is that new?

No idea. I don't have the AWU, I was just curious if it was possible to confuse what the AWU displayed in deco and not know you were in deco. I have a Suunto Zoop and if you don't read the manual on deco, you are likely to be confused with what's displayed when it goes into deco and not know what it meant.