Deep Diving 108 feet w/ a single AL 80 (Air.) No redundancy.

[Storker]

Personally I don't go over 100' anymore,

There's a lot of reasons for limiting oneself to 30m/100'.

Me, I'm kinda susceptible to the nark, and below 30m I start feeling stupid. I don't enjoy being stupid when I have 30m of water between myself and that big, nice, unlimited supply of breathing gas.

 

[Storker]

Are you just using GUE Minimum Gas by itself or using it within a GUE Minimum Deco (now called Pragmatic Minimum Deco) profile?

I don't know the GUE terms, so I can't tell. But all my diving is what's usually referred to as "no-deco" or "no stop". Does that answer your question?

 

[Ayisha]

I don't know the GUE terms, so I can't tell. But all my diving is what's usually referred to as "no-deco" or "no stop". Does that answer your question?

Yes, thank you. I think you're using minimum gas by itself, much like a rock bottom calculation back in the day. I liked the original rock bottom method and used it for over a decade myself.

It's potentially much safer than the typical planning (or maybe no planning) that happens.

 

[boulderjohn]

One of the most popular dives South Florida is the wreck of the Captain Dan, which will take you just a hair past 100 feet--you might hit 105. I have done it many times. It is a lot of fun. Most dive operations will rent you AL 80s for that dive.

For those dives over the years, I used my own LP 85s. When I dived with friends renting tanks from the dive operator we used, those tanks were filled to 3300 PSI, meaning they had roughly 85 cubic feet. (No, these were not the AL 80s rated to 3300.) This dive operation had tank fillers, including especially the manager, who were terrified to fill LP tanks to their rated capacity, let alone over it, so I usually got around 78-80 cubic feet. (Yes, overfilling AL 80s and underfilling LPs is the opposite of normal practice.) Diving Nitrox, we always ended our dives when we used up our NDL time, and we always surfaced with plenty of gas left over.

With all the Covid-19 stuff going on, I don't even know if I will go to Florida this year, but if I do, I will dive the Captain Dan with my LP 85s when that dive is offered. Because I use a different operation for fills, my tanks will have a decent amount of gas in them, but I would do it even with the lesser fill level.

 

[Eric Sedletzky]

I’d answer the question but I better not. Diving has become so politicized and polarized as of late, especially on this board. Sometimes it’s better just to keep your mouth shut.

 

[Boston Breakwater]

Wow... Thread officially "Unwatched." My thanks to the members who stayed on topic, and provided their personal experiences, and views on the O.P.
Cheers.

 

[Ayisha]

Well. I took the OP as a question of whether diving to 108' (33m) carrying only a single Al80 (11L 207 bar) is insane....
The only correct answer to almost any question is "it depends..."

Ok, I took it as site specific, which seemed like it needed some redundancy.

For a typical dive to 108' (or deeper), I do use a single 80 cf and EANx preferred.
Put me in Lake Erie or anywhere at 38 F (3 - 4 C) or with challenging conditions, and I want redundancy.

So yup... it depends.

 

[Storker]

I think you're using minimum gas by itself, much like a rock bottom calculation back in the day. I liked the original rock bottom method and used it for over a decade myself.

Being ESL, I'm not quite up to date on current jargon.

I wasn't aware that there was any fundamental difference between "min gas" and "rock bottom". Me, I prefer "min(imum) gas" as a term since it's a lot more descriptive. "Rock bottom" could mean almost anything.

 

[boulderjohn]

I’d answer the question but I better not. Diving has become so politicized and polarized as of late, especially on this board. Sometimes it’s better just to keep your mouth shut.

Yep.

I really hesitated writing my last couple of posts for this reason. There have been some norms developed on ScubaBoard, norms which represent a tiny, tiny fraction of the divers of the world but have a significant population here. Write anything that violates those norms and your status will plummet.

 

[Ayisha]

Being ESL, I'm not quite up to date on current jargon.

I wasn't aware that there was any fundamental difference between "min gas" and "rock bottom". Me, I prefer "min(imum) gas" as a term since it's a lot more descriptive. "Rock bottom" could mean almost anything.

Minimum gas calculations are much more conservative than the original rock bottom calculations, but more similar to the later rock bottom calculations, which then morphed into minimum gas.
The minimum gas calculation, which is the amount of gas calculated to bring 2 stressed divers to the surface (for MD dives, kind of like NDL) making all stops in a MD ascent profile.
So while rock bottom can change as your depth becomes shallower, MG does not. It isn't supposed to be recalculated unless it was in your plan. Your changing reserve is why I suspected that you were using some variation of rock bottom rather than MG, and perhaps not calculating it as part of a MD ascent profile.
The calculations for each of them and the way they're used are different. Hope that makes sense.