dive planning @ 300' cont.from D&T

[Cave Diver]

Anyone wanna run it in V-planner and see if it works, and post it?

Okay since the poor guy who asked a question about depth and time got his thread highjacked, heres the place to continue...

So I pose this question to the masses..

Your at sealevel, your dive plan is 300' for 10 min. Your back gas consists of two 80's with 12/58, you have one 80 with NX32, and another with NX80 all tanks are AL 80's topped off to 3000psi. Your diving with 5 buddies off a boat that has O2 that hang @ 20' you have a slate and lift bags. Your SAC is .4. Are you gonna do the dive?

Is it doable? Yeah. Would I do it? Still no.

DIVE PLAN
Surface interval = 1 day 0 hr 0 min.
Elevation = 0ft
Conservatism = + 2

Level 300ft 4:20 (10) Trimix 12/58 1.21 ppO2, 93ft ead, 107ft end
Stop at 120ft 1:00 (20) Nitrox 32 1.48 ppO2, 99ft ead
Stop at 30ft 4:00 (37) Nitrox 80 1.53 ppO2, 0ft ead
Stop at 10ft 9:00 (52) Oxygen 1.30 ppO2, 0ft ead
Surface (52) Oxygen -30ft/min ascent.

Off gassing starts at 212.8ft

OTU's this dive: 60
CNS Total: 31.9%

54.6 cu ft Trimix 12/58
16.9 cu ft Nitrox 32
3.0 cu ft Nitrox 80
8.5 cu ft Oxygen
83.1 cu ft TOTAL

Deco plan abbreviated to include only gas switch info.

 

[The Chad]

Yeah but will it work on a cont. plan of 310' for 15min?

 

[Cave Diver]

Yeah but will it work on a cont. plan of 310' for 15min?

My first question is, if you have an event that causes you to run 5 minutes over and 10' deeper, what just happened to your .4 SAC rate?

 

[Meng_Tze]

V-Planner 3.84 by R. Hemingway, VPM code by Erik C. Baker.


Decompression model: VPM - B

DIVE PLAN
Surface interval = 1 day 0 hr 0 min.
Elevation = 0m
Conservatism = + 3

Dec to 60m (4) Trimix 12/58 15m/min descent.
^^^ Low pp ^^^ Low pp ^^^
Dec to 100m (6) Trimix 12/58 18m/min descent.
Level 100m 4:47 (11) Trimix 12/58 1.28 ppO2, 32m ead, 36m end
Asc to 63m (15) Trimix 12/58 -9m/min ascent.
Stop at 63m 0:53 (16) Trimix 12/58 0.85 ppO2, 18m ead, 20m end
Stop at 60m 1:00 (17) Trimix 12/58 0.82 ppO2, 16m ead, 19m end
Stop at 57m 1:00 (18) Trimix 12/58 0.78 ppO2, 15m ead, 18m end
Stop at 54m 1:00 (19) Trimix 12/58 0.75 ppO2, 14m ead, 17m end
Stop at 51m 1:00 (20) Trimix 12/58 0.71 ppO2, 13m ead, 15m end
Stop at 48m 1:00 (21) Trimix 12/58 0.68 ppO2, 12m ead, 14m end
Stop at 45m 1:00 (22) Trimix 12/58 0.64 ppO2, 11m ead, 13m end
Stop at 42m 1:00 (23) Trimix 12/58 0.61 ppO2, 10m ead, 12m end
Stop at 39m 1:00 (24) Trimix 12/58 0.57 ppO2, 8m ead, 10m end
Stop at 36m 1:00 (25) Nitrox 32 1.43 ppO2, 30m ead
^^^ IBCD ppN2 alert ^^^ IBCD ppN2 alert ^^^
Stop at 33m 1:00 (26) Nitrox 32 1.34 ppO2, 27m ead
Stop at 30m 1:00 (27) Nitrox 32 1.25 ppO2, 24m ead
Stop at 27m 1:00 (28) Nitrox 32 1.16 ppO2, 22m ead
Stop at 24m 2:00 (30) Nitrox 32 1.06 ppO2, 19m ead
Stop at 21m 2:00 (32) Nitrox 32 0.97 ppO2, 17m ead
Stop at 18m 3:00 (35) Nitrox 32 0.88 ppO2, 14m ead
Stop at 15m 3:00 (38) Nitrox 32 0.78 ppO2, 11m ead
Stop at 12m 6:00 (44) Nitrox 32 0.69 ppO2, 9m ead
Stop at 9m 5:00 (49) Nitrox 80 1.50 ppO2, 0m ead
Stop at 6m 20:00 (69) Oxygen 1.58 ppO2, 0m ead
Surface (69) Oxygen -9m/min ascent.

Off gassing starts at 72.1m

OTU's this dive: 84
CNS Total: 46.6%

3275.0 ltr Trimix 12/58
855.0 ltr Nitrox 32
139.6 ltr Nitrox 80
479.1 ltr Oxygen
4748.7 ltr TOTAL

equals

115.8 cu ft Trimix 12/58
30.2 cu ft Nitrox 32
4.9 cu ft Nitrox 80
16.9 cu ft Oxygen
167.8 cu ft TOTAL

 

[HowardE]

Why not just use 40% and 100% for deco? That is the same runtime as 32% 80% and 100% - a hell of a lot less to carry too?

The problem I see is lost deco gas scenario... There's not enough back gas to deco out on the back gas alone.

 

[The Chad]

My first question is, if you have an event that causes you to run 5 minutes over and 10' deeper, what just happened to your .4 SAC rate?

Nothing....maybe you just busted the floor

 

[vintagediver]

What about ICD?

 

[addexdiver]

Yep.

62 CF BG
17 CF 32%
15 CF 80%

DecoPlanner with 20/80 GF...36 min of deco starting at 160 ft. Plenty of extra gas. Since you don't mention AL, I assume you have a buddy - so no issues I see.

Rather extrordinary SAC though - .4 - not many honest people would use that...mine is .6 to .65 - and it usually even works out that way...lol.

And I would still do the dive. You would be under thirds on BG and have over 2.5X reserve on deco gas - what is not to like?

Maybe I misread something and the stated SAC was not .4?

...Edited - Huh?, I just re-read the OP, 5 divers - okay, now there is a reason not to do the dive...go 3 and 2 and no issues. Gas is not the problem.

 

[cfenton]

care to explain?

I think rjack321 articulated it better than I could below.

Doubles 80s for a 300ft dive. And your first deco gas is 32%. And then 80%. Blech. Something like V-planner would allow you about 7mins on the bottom. More blech.

Blech blech. About the only thing reasonable about this dive is the 12/58, although I'm not sure where such a precise number like 58% He came from.

So in summary, blech To be honest is wasn't as bad as I initially thought. I internalized the original post using my SAC rate, rather the SAC rate of a small woman.

I wouldn't use 32% for deco, and definitely not 80%. I wouldn't have my first gas switch at 130'. And I'm sure wouldn't go to trouble of the filling, the charter and the deco, for a 10 minute bottom time. Oh yeah...and I'm not trained to 300'.

 

[Meng_Tze]

Yep.

62 CF BG
17 CF 32%
15 CF 80%

DecoPlanner with 20/80 GF...36 min of deco starting at 160 ft. Plenty of extra gas. Since you don't mention AL, I assume you have a buddy - so no issues I see.

Rather extrordinary SAC though - .4 - not many honest people would use that...mine is .6 to .65 - and it usually even works out that way...lol.

And I would still do the dive. You would be under thirds on BG and have over 2.5X reserve on deco gas - what is not to like?

Maybe I misread something and the stated SAC was not .4?

...Edited - O hell, I just re-read the OP, 5 divers - okay there is a reason not to do the dive...go 3 and 2 and no issues. Gas is not the ssue.

Can you recalculate the dive with loss of all deco gas and no buddy? I am curious to see what DecoPlanner gives to run the entire dive on BG on your own.