deco comparison

[Amphiprion]

I'm trying to get a better representation of available deco programs available with the folllowing parameterms (use your own software but say what it is.)

Open circuit you have a working 7. rmv and a resting/deco .5 rmv.

18/40 20 at 200

50ANX deco

what do you run?

 

[sardiverdan]

Just to clear this up a little. You have a working rmv of 7? You will never carry enough gas at that rate no mater what profile you use at 200 FSW. Second do you mean EAN and not ANX?

 

[PfcAJ]

First, I would add a 2nd deco gas. 2nd, this is something you need to know already if you're going to do a dive to 200ft.

 

[Blackwood]

Just to clear this up a little. You have a working rmv of 7? You will never carry enough gas at that rate no mater what profile you use at 200 FSW. Second do you mean EAN and not ANX?

It just looks like he transposed the decimal.

"7." instead of ".7"

Anyway, like PfcAJ, I'd use two deco gases (EAN50 and Oxygen) and have an extra 5% He in my backgas.

Deco I'd run 2:1 ratio deco (i.e. 40 minutes deco) in addition to 1 minute stops starting at 150 and 2 minute stops starting at 100).

 

[rjack321]

I'm trying to get a better representation of available deco programs available with the folllowing parameterms (use your own software but say what it is.)

Open circuit you have a working 7. rmv and a resting/deco .5 rmv.

18/40 20 at 200

50ANX deco

what do you run?

Staying on the boat.

 

[Michael Kazma]

There is nothing wrong with the profile you are asking about but I would also decrease me END. Here is the profile run in v-planner with a conservatism of +1 on the VPM-B model:

V-Planner 3.85 by Ross Hemingway,
VPM code by Erik C. Baker.

Decompression model: VPM - B

DIVE PLAN
Surface interval = 5 day 0 hr 0 min.
Elevation = 0ft
Conservatism = + 1

Dec to 200ft (4) Trimix 18/40 50ft/min descent.
Level 200ft 16:00 (20) Trimix 18/40 1.27 ppO2, 91ft ead, 107ft end
Asc to 120ft (22) Trimix 18/40 -30ft/min ascent.
Stop at 120ft 0:20 (23) Trimix 18/40 0.83 ppO2, 48ft ead, 59ft end
Stop at 110ft 1:00 (24) Trimix 18/40 0.78 ppO2, 43ft ead, 53ft end
Stop at 100ft 1:00 (25) Trimix 18/40 0.72 ppO2, 38ft ead, 47ft end
Stop at 90ft 1:00 (26) Trimix 18/40 0.67 ppO2, 32ft ead, 41ft end
Stop at 80ft 2:00 (28) Trimix 18/40 0.62 ppO2, 27ft ead, 35ft end
Stop at 70ft 2:00 (30) Nitrox 50 1.56 ppO2, 32ft ead
Stop at 60ft 1:00 (31) Nitrox 50 1.41 ppO2, 26ft ead
Stop at 50ft 2:00 (33) Nitrox 50 1.26 ppO2, 20ft ead
Stop at 40ft 3:00 (36) Nitrox 50 1.10 ppO2, 13ft ead
Stop at 30ft 5:00 (41) Nitrox 50 0.95 ppO2, 7ft ead
Stop at 20ft 20:00 (61) Nitrox 50 0.80 ppO2, 1ft ead
Surface (61) Nitrox 50 -30ft/min ascent.

Off gassing starts at 148.4ft

OTU's this dive: 61
CNS Total: 22.4%

112.3 cu ft Trimix 18/40
31.2 cu ft Nitrox 50
143.5 cu ft TOTAL

 

[sardiverdan]

My point is that if that many mistakes are in a short post I wonder about the entire pre-dive planning worksheet. Problem with internet is you don't really know if the person on the other end is actually trained to use the profile you provide. If they are trained they would already know about the diffrent profiles and would already be using the one they find most compatable. The OP is IANTD trained. I went through IANTD to do some of my original deep deco training about 17 years ago. Back then the dives were on air to 200 FSW and the deco mix was set at EAN 36 and 100%O2. Just a word of caution about providing enough info to get a novice diver in trouble

 

[rjack321]

There is nothing wrong with the profile you are asking about but I would also decrease me END.

The END is not that big a deal. Lose that EAN50 bottle and then see what you're stuck doing...

 

[Michael Kazma]

The END is not that big a deal. Lose that EAN50 bottle and then see what you're stuck doing...

A very long deco for the bottom profile, but losing my deco gas is not a common thing and as long as I have enough other gas to do my deco in this event I am happy.

 

[Blackwood]

Just a word of caution about providing enough info to get a novice diver in trouble

Micheal posted a commercially available profile, and mine was (I believe) sufficiently incomplete ("40 minutes") that I'm not too worried about implied liability.

Good point, though. Many of us often censor ourselves or refrain from answering certain questions for just that reason.

My suspicion in this case is that someone who has access to 18/40 has been trained.