Travel Gas labeling and Counter Diffusion

[BDub]

Was thinking more a 20 -30 foot per min descent , sorry for the confusion. Plus it hard to get 3500 psi in the 108's everywhere

Right, a 20ft/min descent to 200ffw is 10 minutes

That's a long descent, using a lot of gas, and depending on when you start your deco clock, racking up a lot of unnecessary deco.

[CaptnJack]

I/we aim for descents in the 70ft/min range. So ~3mins to 200ft. 4mins max.

Was thinking more a 20 -30 foot per min descent , sorry for the confusion. Plus it hard to get 3500 psi in the 108's everywhere Was thinking more like a low 80 min runtime with 16 min or so at depth.

Is this what you were trained to do?

[doublesunder]

I/we aim for descents in the 70ft/min range. So ~3mins to 200ft. 4mins max.

Was thinking more a 20 -30 foot per min descent , sorry for the confusion. Plus it hard to get 3500 psi in the 108's everywhere Was thinking more like a low 80 min runtime with 16 min or so at depth.

Is this what you were trained to do?

I fully agree with quick descents when possible, as well as being cautioned about costs of helium for being slow I see everyone's point, that there is more than one thing to gain with quicker descents. Decompression times go way down as well as gas consumption. All input is appreciated

[kdupreez]

Right, a 20ft/min descent to 200ffw is 10 minutes

Doh.. a little math-up there

Wel.. err.. I thought we were cruzin on down, then stopping half way for another 10min to smell the roses.. I hear they are really great down there too!

:luv:

[CaptnJack]

Wel.. err.. I thought we were cruzin on down, then stopping half way for another 10min to smell the roses.. I hear they are really great down there too!

It happens, sometimes its just the profile of the dive. Its the primary reason I use average depth for depth in "tables".

[loanwolf]

This is at 50' decent

Decompression model: VPM - B + GFS/90

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

Dec to 200ft (4) Trimix 18/45 50ft/min descent.
Level 200ft 26:00 (30) Trimix 18/45 1.27 ppO2, 76ft ead, 95ft end
Asc to 130ft (32) Trimix 18/45 -30ft/min ascent.
Stop at 130ft 0:40 (33) Trimix 18/45 0.89 ppO2, 43ft ead, 57ft end
Stop at 120ft 1:00 (34) Trimix 18/45 0.83 ppO2, 39ft ead, 51ft end
Stop at 110ft 1:00 (35) Trimix 18/45 0.78 ppO2, 34ft ead, 46ft end
Stop at 100ft 2:00 (37) Trimix 18/45 0.72 ppO2, 29ft ead, 40ft end
Stop at 90ft 2:00 (39) Trimix 18/45 0.67 ppO2, 25ft ead, 35ft end
Stop at 80ft 3:00 (42) Trimix 18/45 0.62 ppO2, 20ft ead, 29ft end
Stop at 70ft 2:00 (44) Nitrox 50 1.56 ppO2, 32ft ead
Stop at 60ft 3:00 (47) Nitrox 50 1.41 ppO2, 26ft ead
Stop at 50ft 3:00 (50) Nitrox 50 1.26 ppO2, 20ft ead
Stop at 40ft 5:00 (55) Nitrox 50 1.10 ppO2, 13ft ead
Stop at 30ft 7:00 (62) Nitrox 80 1.53 ppO2, 0ft ead
Stop at 20ft 31:00 (93) Nitrox 80 1.28 ppO2, 0ft ead
Surface (93) Nitrox 80 -30ft/min ascent.

Off gassing starts at 153.3ft

OTU's this dive: 124
CNS Total: 48.3%

194.9 cu ft Trimix 18/45
19.8 cu ft Nitrox 50
38.0 cu ft Nitrox 80
252.8 cu ft TOTAL

This is 20' decent

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

Dec to 200ft (10) Trimix 18/45 20ft/min descent.
Level 200ft 20:00 (30) Trimix 18/45 1.27 ppO2, 76ft ead, 95ft end
Asc to 130ft (32) Trimix 18/45 -30ft/min ascent.
Stop at 130ft 0:40 (33) Trimix 18/45 0.89 ppO2, 43ft ead, 57ft end
Stop at 120ft 1:00 (34) Trimix 18/45 0.83 ppO2, 39ft ead, 51ft end
Stop at 110ft 1:00 (35) Trimix 18/45 0.78 ppO2, 34ft ead, 46ft end
Stop at 100ft 1:00 (36) Trimix 18/45 0.72 ppO2, 29ft ead, 40ft end
Stop at 90ft 3:00 (39) Trimix 18/45 0.67 ppO2, 25ft ead, 35ft end
Stop at 80ft 2:00 (41) Trimix 18/45 0.62 ppO2, 20ft ead, 29ft end
Stop at 70ft 2:00 (43) Nitrox 50 1.56 ppO2, 32ft ead
Stop at 60ft 3:00 (46) Nitrox 50 1.41 ppO2, 26ft ead
Stop at 50ft 3:00 (49) Nitrox 50 1.26 ppO2, 20ft ead
Stop at 40ft 4:00 (53) Nitrox 50 1.10 ppO2, 13ft ead
Stop at 30ft 6:00 (59) Nitrox 80 1.53 ppO2, 0ft ead
Stop at 20ft 26:00 (85) Nitrox 80 1.28 ppO2, 0ft ead
Surface (85) Nitrox 80 -30ft/min ascent.

Off gassing starts at 152.3ft

OTU's this dive: 110
CNS Total: 42.7%

178.2 cu ft Trimix 18/45
18.5 cu ft Nitrox 50
32.1 cu ft Nitrox 80
228.8 cu ft TOTAL

Check your gas consumptions, they are right to spend more than 10 min on the car is tough as hell even with a vid camera.

[doublesunder]

Why are you using Decompression model: VPM - B + GFS/90 over plain VPM-B, they seem very similar? Is the GFS/90 based on most restrictive time /ceiling?



Decompression model: VPM - B

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

Dec to 200ft (4) Trimix 18/45 50ft/min descent.
Level 200ft 26:00 (30) Trimix 18/45 1.27 ppO2, 76ft ead, 95ft end
Asc to 130ft (33) Trimix 18/45 -20ft/min ascent.
Stop at 130ft 0:30 (34) Trimix 18/45 0.89 ppO2, 43ft ead, 57ft end
Stop at 120ft 1:00 (35) Trimix 18/45 0.83 ppO2, 39ft ead, 51ft end
Stop at 110ft 1:00 (36) Trimix 18/45 0.78 ppO2, 34ft ead, 46ft end
Stop at 100ft 2:00 (38) Trimix 18/45 0.72 ppO2, 29ft ead, 40ft end
Stop at 90ft 2:00 (40) Trimix 18/45 0.67 ppO2, 25ft ead, 35ft end
Stop at 80ft 3:00 (43) Trimix 18/45 0.62 ppO2, 20ft ead, 29ft end
Stop at 70ft 3:00 (46) Nitrox 50 1.56 ppO2, 32ft ead
Stop at 60ft 2:00 (48) Nitrox 50 1.41 ppO2, 26ft ead
Stop at 50ft 4:00 (52) Nitrox 50 1.26 ppO2, 20ft ead
Stop at 40ft 5:00 (57) Nitrox 50 1.10 ppO2, 13ft ead
Stop at 30ft 6:00 (63) Nitrox 80 1.53 ppO2, 0ft ead
Stop at 20ft 28:00 (91) Nitrox 80 1.28 ppO2, 0ft ead
Surface (92) Nitrox 80 -20ft/min ascent.

Off gassing starts at 149.3ft

OTU's this dive: 121
CNS Total: 47.1%

213.2 cu ft Trimix 18/45
23.3 cu ft Nitrox 50
36.9 cu ft Nitrox 80
273.4 cu ft TOTAL

[loanwolf]

Why are you using Decompression model: VPM - B + GFS/90 over plain VPM-B, they seem very similar? Is the GFS/90 based on most restrictive time /ceiling?

I have a Shearwater and still use GF set at 10/90 most of the time so it seams to match up better using that as to what I will get on my CCR on a live dive. the time is not that much different when you look at them over all i have found it really does not make all that much difference in the long run, especially if you dive a computer reading depth and time live over using bottom timers and hard tables.

[doublesunder]

I am using a X1 with Vplanner Live, I was thinking that the Multideco model was very similar to yours.

I mean strictly for use as a backup light.

[kdupreez]

MultiDeco can do both VPM or Buhlmann based dive profiles.

My opinion is that gradient factors are a just a "fixes" to the Haldanian rooted model's M values.. It patches the model to start deco sooner and slow ascend and closely mimics what bubble models are doing to the profile when "managing bubble growth".. so in all honesty,. both M values and Gradient Factors are mathematical fixes to patch an empirical model..

Hence a GFS 10/90 being so close to a VPM-B.. But, the longer and deeper the dive, the more these models will vary though..

I would encourage you to look at both when planning your dives and create a deco profile based on a combination of the them and use them within the boundaries what they are good for and apply additional padding for conservatism, environment and team factors.

we call this "pragmatic decompression" .. Don't just blindly follow that "math box" on your wrist.. know what its simulating and apply your own sound judgement.

.

[doublesunder]

MultiDeco can do both VPM or Buhlmann based dive profiles.

My opinion is that gradient factors are a just a "fixes" to the Haldanian rooted model's M values.. It patches the model to start deco sooner and slow ascend and closely mimics what bubble models are doing to the profile when "managing bubble growth".. so in all honesty,. both M values and Gradient Factors are mathematical fixes to patch an empirical model..

Hence a GFS 10/90 being so close to a VPM-B.. But, the longer and deeper the dive, the more these models will vary though..

I would encourage you to look at both when planning your dives and create a deco profile based on a combination of the them and use them within the boundaries what they are good for and apply additional padding for conservatism, environment and team factors.

we call this "pragmatic decompression" .. Don't just blindly follow that "math box" on your wrist.. know what its simulating and apply your own sound judgement.

.

+1 I fully agree on your statement I always plan dives with tables in respect to conditions and conservatism. Which is why I orginally asked the question about using a intermediate gas to optimize decompression. One of the reasons I choose the X1 is it closely follows my Vplanner schedule. However, there is always a certain amount of risk that we accept to enjoy the places we frequent.

[CaptnJack]

+1 I fully agree on your statement I always plan dives with tables in respect to conditions and conservatism. Which is why I orginally asked the question about using a intermediate gas to optimize decompression. One of the reasons I choose the X1 is it closely follows my Vplanner schedule. However, there is always a certain amount of risk that we accept to enjoy the places we frequent.

"Travel gas" is an older term used to describe a gas used to get below a floor above which you cannot breathe your hypoxic backgas. As you now know, people don't use travel gases anymore. And even if you did, it wouldn't have any influence on later decompression.

I can't think of any local normoxic trimix dives which would benefit from a 3rd decompression gas.

[doublesunder]

+1 I fully agree on your statement I always plan dives with tables in respect to conditions and conservatism. Which is why I orginally asked the question about using a intermediate gas to optimize decompression. One of the reasons I choose the X1 is it closely follows my Vplanner schedule. However, there is always a certain amount of risk that we accept to enjoy the places we frequent.

"Travel gas" is an older term used to describe a gas used to get below a floor above which you cannot breathe your hypoxic backgas. As you now know, people don't use travel gases anymore. And even if you did, it wouldn't have any influence on later decompression.

I can't think of any local normoxic trimix dives which would benefit from a 3rd decompression gas.

Whats your opinion on Argon Bottle mounting, on the plate or quick mount on doubles? Currently have a 13 cu off of the plate, but was thinking of mounting different.

[BDub]

Whats your opinion on Argon Bottle mounting, on the plate or quick mount on doubles? Currently have a 13 cu off of the plate, but was thinking of mounting different.

I mount my al6 on my backplate, like so. When using an al13/14 I mount on it my doubles.

[doublesunder]

Whats your opinion on Argon Bottle mounting, on the plate or quick mount on doubles? Currently have a 13 cu off of the plate, but was thinking of mounting different.

I mount my al6 on my backplate, like so. When using an al13/14 I mount on it my doubles.

Thats how I was mounting my al6 and my al13, do you have a pic on mounting to doubles? Many thanks...

[Joshua Smith]

Whats your opinion on Argon Bottle mounting, on the plate or quick mount on doubles? Currently have a 13 cu off of the plate, but was thinking of mounting different.

I mount my al6 on my backplate, like so. When using an al13/14 I mount on it my doubles.

Hey, that's a handy reference page! Been a while since I looked at your site. Nice job!

I was interested to see that you just punch holes in the webbing and mount it to the plate. I add a SS Grommet to the hole- bought a kit for pretty cheap at Seattle Fabrics.

And after running out of inflation gas for about the 75th tech dive in a row, I switched over to a 13 cf bottle.....of course, as was recently pointed out in another thread, I use my suit for buoyancy, so I use a lot more gas there. And I kept the same location with the bottle. Why do you move locations for a bigger bottle?

[CaptnJack]

[


And after running out of inflation gas for about the 75th tech dive in a row, I switched over to a 13 cf bottle.....of course, as was recently pointed out in another thread, I use my suit for buoyancy, so I use a lot more gas there. And I kept the same location with the bottle. Why do you move locations for a bigger bottle?

The 13cf under the arm pinches the wing and with stages on generally makes everything crowded in the armpit. I have 2 al6s and 2 al13s. I actually prefer the 13s as I'm lazy and I don't need to fill them full-full to get a couple dives out of them. I'd like some lp14s even better but they aren't made anymore and I can justify buying more inflation tanks.

[Joshua Smith]

[


And after running out of inflation gas for about the 75th tech dive in a row, I switched over to a 13 cf bottle.....of course, as was recently pointed out in another thread, I use my suit for buoyancy, so I use a lot more gas there. And I kept the same location with the bottle. Why do you move locations for a bigger bottle?

The 13cf under the arm pinches the wing and with stages on generally makes everything crowded in the armpit. I have 2 al6s and 2 al13s. I actually prefer the 13s as I'm lazy and I don't need to fill them full-full to get a couple dives out of them. I'd like some lp14s even better but they aren't made anymore and I can justify buying more inflation tanks.

Hmm. It's just a bit crowded for me, but I got used to it pretty fast.

[BDub]

Hey, that's a handy reference page! Been a while since I looked at your site. Nice job!

I was interested to see that you just punch holes in the webbing and mount it to the plate. I add a SS Grommet to the hole- bought a kit for pretty cheap at Seattle Fabrics.

And after running out of inflation gas for about the 75th tech dive in a row, I switched over to a 13 cf bottle.....of course, as was recently pointed out in another thread, I use my suit for buoyancy, so I use a lot more gas there. And I kept the same location with the bottle. Why do you move locations for a bigger bottle?

Thanks, dude!

Eh, I didn't include grommets on the page because I don't think they're absolutely necessary. I personally don't use them, and have several hundred dives on the current piece of webbing I'm using without them, but I see merit in using grommets as well, and have used them in the past.

As far as the 13cuft mounted on my backgas....what Richard said. It's more a PITA than anything else. In a pinch, if my only option was mounting it on the backplate, I'd do it. I'm certainly not going to sit out a dive because of it, but it's not my preference.

Thats how I was mounting my al6 and my al13, do you have a pic on mounting to doubles? Many thanks...

Diving all day tomorrow, but will post pics soon.

Hmm. It's just a bit crowded for me, but I got used to it pretty fast.

That's what she said!

Thank you, I'll be here all night!

[kdupreez]

Brian, dude that web site rocks! Well done!

And +1 on the al13 getting a little tight back there. Especially on the surface when your wing is fully inflated it does a good job bruising your liver

[doublesunder]

Did anyone ever come up with a picture showing postion of there Argon mount for backgas?

[lamont]

( from http://www.globalunderwaterexplorers.or ... bly-images )

[doublesunder]

Awesome!! Thanks!!, I was wondering how much it was canted foward! What length hose did you end up using?

[CaptnJack]

Awesome!! Thanks!!, I was wondering how much it was canted foward! What length hose did you end up using?

got any pics of whatever argon bottle system you're using?

[doublesunder]

Awesome!! Thanks!!, I was wondering how much it was canted foward! What length hose did you end up using?

got any pics of whatever argon bottle system you're using?

This is what I am currently using, but as noted it is becoming crowded.