Standard MOD

[LiteHedded]

I think it comes down to taking the right gas in the right tank with the right marking.

If you're MOD for said dive is 150, then put a 5 over the 9 and go.

I'm quite the fan of 150, 200, 250 and 300 markings, but Ill dive 190 and 240 markings all day long. Rjack mentioned earlier about bottom MODs being a bit flexible, and I agree 100%.

And AG saying something doesn't make it correct, esp when the video footage suggests otherwise. Also, back then, many things were different. I'm sure no ones suggesting color coding tanks anymore, either.

Dalec, we use standard gases for certain depth ranges and certain markings. If ithe plan calls for show ing up with 190 gas, were all going to have 18/45. That's the beauty of having a truly standardized system. Having your stage unmarked means no one can easily and readily tell what's in there. The info is scrawled on a piece of tape somewhere. I cannot fathom that being superior to big, bold markings that everyone can see.

Also, if no math is needed, then what exactly are you checking on the analysis tape? Your scribbled initials? That's a good way to do the funky chicken at 200ft.

I've accidentally clipped off someone elses tank before. The big Richardson sticker tipped me off, and we just traded back

What's really going on here is utd has too many gasses for each depth, and can't realistically mark them all. "Utd/dir long duration ppo2 of .7" and I think 1.0 for regular...double for each depth range? I have 3 stage markings on my tank fleet: 100, 190, and 300. Done. If I did more at the 150 range, id own a few of those, too.

it's a pretty sweet sticker huh??

 

[rjack321]

Yea, point 8 from AGs post that was linked earlier. Pretty interesting, to say the least...

I made an error above, though. Its 0.7 for long duration and 1.2 for short, apparently. I apologize for any (additional) confusion.

Sorta but its nothing new.

The premise being that you back off to the next deeper gas if the conditions are aggressive. Similar to GUE position on a 165ft dive - you might go with 21/35 if its short in a warm ocean with a live boat. Long and cold in a cave you'd probably step up to 18/45. In neither case has the maximum operating depth of the gas changed.

AG was just putting some boundaries/guidelines on that (which is fine), but honestly he mixed up the "depth being used at" with the "maximum" issue.

 

[gsk3]

Please excuse a naive question about marking: If MOD for the same gas when used for deco vs. bottom gas is different, then why isn't there an additional label on the deco gas? E.g. 3" boat letters for the MOD, plus "DECO" in 1" letters below that or something similar?

 

[lamont]

Yea, point 8 from AGs post that was linked earlier. Pretty interesting, to say the least...

I made an error above, though. Its 0.7 for long duration and 1.2 for short, apparently. I apologize for any (additional) confusion.

I'm just confused by the standards. The 0.7 ppO2 seems very low, and its only going to be applicable to *very* long (say 8+ hour BT) dives where you start to worry about pulmonary tox -- those are going to be project dives, and I'd say that absolutely the tanks get proper MOD stickers at that ppO2 on them.

Coming back to your previous point, it seems like the vast majority of dives done will only require a few different mixes and MODs, and they definitely should have proper MOD stickers. Anything outside of that will be project diving, and the project members should take the time to properly mark the tanks.

 

[rjack321]

Please excuse a naive question about marking: If MOD for the same gas when used for deco vs. bottom gas is different, then why isn't there an additional label on the deco gas? E.g. 3" boat letters for the MOD, plus "DECO" in 1" letters below that or something similar?

Because its really not a problem to use a gas shallower than marked depth. E.g. not taking 21/35 when used as backgas to 190ft.

"maximum depth" is just that, it doesn't really put limits on what you might what to average or how.

 

[gsk3]

Because its really not a problem to use a gas shallower than marked depth. E.g. not taking 21/35 when used as backgas to 190ft.

"maximum depth" is just that, it doesn't really put limits on what you might what to average or how.

I see. So the main concern is, acutely if we switch to this gas will we oxtox?

It seems to me there are other hazards, though, like running out of gas if you spend your deco stop on bottom gas instead of deco gas. But I guess then you've probably been decompressing a little on the bottom gas at a shallower depth (although there's a window where you would still be ongassing), so the same deco gases as before will still work? Aside from deco bottles usually being 40s not 80s, how do you tell which gas is which?

I guess what I'm asking, from the perspective of a Fundies-only diver, is how do you figure out what bottle is which? If the plan calls for 18/45 then 21/35 then 30/30 then 50 as you ascend, how do you tell the difference between all the 80's? Are you looking at the analysis sticker and your team is verifying it's safe from the MOD? Doesn't that leave open the possibility that you switch to the wrong gas, since the diver is the only one seeing the contents? Or is the MOD non-ambiguous even with the different pPO2 labeling for deco vs. bottom gas?

 

[Scott L]

What did you guys decide? Do I rip-off my GUE MOD stickers from bottles?

 

[ScubaFeenD]

What did you guys decide? Do I rip-off my GUE MOD stickers from bottles?

 

[ucfdiver]

I see. So the main concern is, acutely if we switch to this gas will we oxtox?

It seems to me there are other hazards, though, like running out of gas if you spend your deco stop on bottom gas instead of deco gas. But I guess then you've probably been decompressing a little on the bottom gas at a shallower depth (although there's a window where you would still be ongassing), so the same deco gases as before will still work? Aside from deco bottles usually being 40s not 80s, how do you tell which gas is which?

I guess what I'm asking, from the perspective of a Fundies-only diver, is how do you figure out what bottle is which? If the plan calls for 18/45 then 21/35 then 30/30 then 50 as you ascend, how do you tell the difference between all the 80's? Are you looking at the analysis sticker and your team is verifying it's safe from the MOD? Doesn't that leave open the possibility that you switch to the wrong gas, since the diver is the only one seeing the contents? Or is the MOD non-ambiguous even with the different pPO2 labeling for deco vs. bottom gas?

18/45 = 190
21/35 = 150
30/30 = 100 (some mark this 120, but since 120 is a deco gas...)
50/0 = 70

Really easy to figure this all out. That's the beauty of keeping things standard. We don't have a 20ft stage bottle, 70ft stage bottle, 150ft deco bottle, etc. There's a few cases where deco gases could be marked the same as bottom gases (120 bottle being an example), but it's incredibly difficult to show an example of a dive where this is an issue.

Here's litehedded on a manatee dive we did, everything is marked. With AG's way, who knows what bottom mix you're breathing if you grabbed the wrong bottle that morning.

 

[LiteHedded]

What did you guys decide? Do I rip-off my GUE MOD stickers from bottles?

well I decided not marking bottles is dumb, and no argument has been made that makes any sense at all to sway me from that position.