2 deco bottles

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Permalink Reply by robert lucas on October 11, 2009 at 6:39pm

Thanks for the reply.
25 to 30 minutes BT, avg depth 160', 35 minutes for deco, .3 to .5 deco SCR, yes on lost gas, lost 50%=13cf 02'
needed, lost 02=32cf of 50%, loss of 2 deco gases 182cf 21/35 needed, LP 85's @30000psi =196CF. I think loss of 2 gases is pretty slim. Teammates have lower or same SCR. Any point of view would be appreciated.

Dec to 160ft (3) Triox 21/35 50ft/min descent.
Level 160ft 26:48 (30) Triox 21/35 1.23 ppO2, 74ft ead, 92ft end
Asc to 120ft (31) Triox 21/35 -30ft/min ascent.
Level 120ft 0:18 (31) Triox 21/35 0.97 ppO2, 52ft ead, 66ft end
Asc to 110ft (31) Triox 21/35 -30ft/min ascent.
Level 110ft 0:18 (32) Triox 21/35 0.91 ppO2, 47ft ead, 60ft end
Asc to 90ft (32) Triox 21/35 -30ft/min ascent.
Stop at 90ft 0:04 (33) Triox 21/35 0.78 ppO2, 35ft ead, 47ft end
Stop at 80ft 1:00 (34) Triox 21/35 0.72 ppO2, 30ft ead, 40ft end
Stop at 70ft 4:00 (38) Nitrox 50 1.56 ppO2, 32ft ead
Stop at 40ft 3:20 (42) Nitrox 50 1.10 ppO2, 13ft ead
Stop at 30ft 5:00 (47) Nitrox 50 0.95 ppO2, 7ft ead
Stop at 20ft 6:00 (53) Oxygen 1.60 ppO2, 0ft ead
Stop at 10ft 10:00 (63) Oxygen 1.30 ppO2, 0ft ead
Surface (63) Oxygen -30ft/min ascent.

OTU's this dive: 86
CNS Total: 41.0%

110.7 cu ft Triox 21/35
12.4 cu ft Nitrox 50
9.0 cu ft Oxygen
132.1 cu ft TOTAL

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Permalink Reply by robert lucas on October 11, 2009 at 7:19pm

Thanks again, jut trying to travel as light as possible and still be on the safe side. Bad back and getting older.
Regards BOB L

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Permalink Reply by Richard on October 11, 2009 at 9:18pm

Full 30s are fine for O2. Similar amount of gas that I transfill into my 40s (2000-2100psi) since I don't have a booster.

You're v-planner deco has a significantly different profile than what me and my team do for a 30min dive to 160ft. For one, you're short time at 70, and completely missing the 50 and 60ft stops. If you did deco "the UTD" way you'd probably go with 40s of EAN50 since the gas needs are different. Since you are doing different times and shapes I can't comment on the effectiveness of using 30s of EAN50 for your plans.

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Permalink Reply by robert lucas on October 12, 2009 at 7:48am

Thanks for the reply.

Richard said:

Full 30s are fine for O2. Similar amount of gas that I transfill into my 40s (2000-2100psi) since I don't have a booster.

You're v-planner deco has a significantly different profile than what me and my team do for a 30min dive to 160ft. For one, you're short time at 70, and completely missing the 50 and 60ft stops. If you did deco "the UTD" way you'd probably go with 40s of EAN50 since the gas needs are different. Since you are doing different times and shapes I can't comment on the effectiveness of using 30s of EAN50 for your plans.

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Permalink Reply by Maciej Arkuszewski on October 12, 2009 at 11:23am

Hi Robert.

We are not using VPM generated profiles or gas management tools built into it in dive planning at all - it would be questionable for our instructors to comment on something that is clearly outside of what we teach. I'm guessing that taking UTD course is not feasible for you, but it might be beneficial to you if you familiarize yourself with our approach by having a look at on-line presentations (which can be accessed by anyone for a moderate fee).

With that said, I think that SAC .3 sounds very optimistic when hauling 2 deco bottles in a current.

Regards
Maciek

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Permalink Reply by Marc Blackwood on October 12, 2009 at 12:24pm

Maciej Arkuszewski said:

Hi Robert.

With that said, I think that SAC .3 sounds very optimistic when hauling 2 deco bottles in a current.

Regards
Maciek

Or in a swimming pool with singles. g-damn!

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Permalink Reply by robert lucas on October 12, 2009 at 4:55pm

Thanks for the reply, but maybe you should concider using a deco program, gas planning tools and tweak as needed. I assume you deco on a line in a current, not in Florida there's something they call drift diving, just shoot a bag and hang out in 83 deg water. And your right, your reply is questionable, sounds like the old Tec list.

Maciej Arkuszewski said:

Hi Robert.

We are not using VPM generated profiles or gas management tools built into it in dive planning at all - it would be questionable for our instructors to comment on something that is clearly outside of what we teach. I'm guessing that taking UTD course is not feasible for you, but it might be beneficial to you if you familiarize yourself with our approach by having a look at on-line presentations (which can be accessed by anyone for a moderate fee).

With that said, I think that SAC .3 sounds very optimistic when hauling 2 deco bottles in a current.

Regards
Maciek

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Permalink Reply by robert lucas on October 12, 2009 at 5:09pm

No mention of hauling 2 deco bottles with a sac rate of .3. The question was , if it was feasable to haul AL30 and AL 20 on a 160' dive. You guys are a little closed minded with diving conditions, so I'm assuming you dive in cold water,dry suit and hang on a line for deco, not so in this part of the world. Read the tread again. I only dive with a AL 40 , try to be opitmistic as qpposed to pesimistic:-)

Marc Blackwood said:

Maciej Arkuszewski said:

Hi Robert.

With that said, I think that SAC .3 sounds very optimistic when hauling 2 deco bottles in a current.

Regards
Maciek

Or in a swimming pool with singles. g-damn!

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Permalink Reply by Richard on October 12, 2009 at 9:34pm

Assuming just the one dive, for 30mins @ 160 I'd do:

70-5 on EAN50
60-5 on EAN50
50-2 on EAN50
40-2 on EAN50 using about 20cf total
30-4 on backgas
20-12 on O2
5 min ascent on O2 using about 12cf

Lost EAN50 we'd use about 35cf between me and a buddy.

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Permalink Reply by robert lucas on October 13, 2009 at 6:28pm

Hey Rich , My panties are squared away :-). That is pretty close to my profile after tweaking V-Planner, but no back gas breaks. I add to the 70' stop : 70/5 and throw in 1 minute stops for 60',50' then switch 10' stop with 20' stop and 5 to surface.
V=Planner gives cresdit for .30 sec deep stop at 120'. In any event will take a 40cf of 50% . After seeing AG video will nose clip 20 cf of 02 to hip D ring . Very interesting, why back gas at 30/4?

Regards
BOB L

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Permalink Reply by Richard on October 13, 2009 at 9:22pm

I'm sure Rainer is happy your undies aren't all twisted lol.

For this kind of exposure backgas at 30 is just because you need to go from the EAN50 to the long hose before switching to the O2. Switching from EAN50 to O2 is do-able but its easy to have a CF - esp. if there's any kind of issue at the time.

Personally I only nose clip O2 bottles in caves where I am dropping it at 20ft in the first couple mins. I wouldn't do a whole OW or wreck dive that way, reaching the spg is a pain when the bottle's nose is so close/tight. For just 2 narrow bottles (like 30s or 40s) I keep them up front for the dive. I only add a leash for the 3rd bottle.

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Permalink Reply by robert lucas on October 14, 2009 at 6:12am

Great Info, Thanks.

Richard said:

I'm sure Rainer is happy your undies aren't all twisted lol.

For this kind of exposure backgas at 30 is just because you need to go from the EAN50 to the long hose before switching to the O2. Switching from EAN50 to O2 is do-able but its easy to have a CF - esp. if there's any kind of issue at the time.

Personally I only nose clip O2 bottles in caves where I am dropping it at 20ft in the first couple mins. I wouldn't do a whole OW or wreck dive that way, reaching the spg is a pain when the bottle's nose is so close/tight. For just 2 narrow bottles (like 30s or 40s) I keep them up front for the dive. I only add a leash for the 3rd bottle.

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