"Reasonable" Deep Air...

[SWFTD]

Thanks for all the input. I don't want to reinvent the wheel so appreciate it. Since I dive where there is usually a lot of current, consider most of my dives to have physically strenuous parts (for me), and usually do penetrations, I guess I will have to just pay for the mix. May dive a little less often, though.

 

[Kevrumbo]

Attached is the itemized Gas Bill from the Truk Lagoon Dive Center for my past two trips, 18-26Nov'12 and 14-30Dec'12 --and I mostly used Deep Air/Nitrox for the trip just completed last month. (Used Helium sparingly for 20/20 Economy Mix, and one nearly standardized GUE Mix of 17/40 for the Katsuragisan Maru at 67m max/60m ave).

The bulk of the gas costs for both trips combined was Oxygen for Eanx25, 28, 30 & 32; and deco gas blending for Eanx50 & 100. . .

(It gets expensive overseas anyway . . .even if you choose to skimp on using Helium!!!):shocked2:

 

[ucfdiver]

btw, the only useful knot I can tie underwater is the double overhand knot into a loop (good for forming loops at the ends of a broken line, so you can bridge them together with a gap/safety reel). . .

I *ALWAYS* use this knot. Very fast, very effective. Since all my spools have loops in both ends, it makes for an easy patch.

 

[rjack321]

I *ALWAYS* use this knot. Very fast, very effective. Since all my spools have loops in both ends, it makes for an easy patch.

I know I can't tie bowlines or fisherman's knots with gloves on. Waste of time. So I use a single overhand loop too, fast and you instantly know it secure (or not).

 

[Stoo]

I suspect that I am older than a few of you here, but I grew up diving deepish air, starting in '74. I routinely dive to about 180' on air, here in the Great Lakes. My personal "test" for narcosis is whether I can still use my camera system effectively and I would say that 99% of the time I can. On the odd occasion, I find myself staring at the back of it thinking "So many buttons..." Time to go up.

For whatever reason, I have never had happy narcs. When I do acknowledge narcosis, I would say it will manifest as the proverbial "dark narc"... a general feeling of stress and "I-don't-wanna-be-here-anymore"-ness. So I head up... But that is extremely rare.

I have friends that dive mix on anything over about 110'. I just think that's dumb...

 

[DevonDiver]

The deepest air dives I've done were 86m/282ft. That was some time ago and I wouldn't do that now. Narcosis was extensive, even if not 'obvious' whilst at depth. Dives went fine (some were solo/night too..) but often extensive amnesia afterwards... silly... the perils of youth

My personal limit, given tropical diving in good conditions is circa 60m/200ft. However, that will vary depending how I feel on the day and the specific dive mission. That limit, needless to say, is significantly lower if penetration is involved.

Was doing some exploratory wreck identification dives the other week, depth was just 45m/150ft... I was cursing the narcosis as it significantly limited what was being observed/interpreted on the dive. Felt absolutely fine on the dives... only when reviewing the GoPro footage afterwards was I kicking myself for 'not seeing' stuff that was plainly right in front of me. End result - less was achieved on multiple dives than I would have achieved on a single dive with appropriate narcosis management/gas selection.

As the OP points out though - helium is very cost-restrictive. It's a balance between (1) safety, (2) your mission/goals/what you want to achieve and (3) cost. Safety shouldn't be compromised (yes, we all have different definitions of where that line lays) - which otherwise leaves a cost-benefit calculation for trimix use.

 

[Stoo]

Dives went fine (some were solo/night too..) but often extensive amnesia afterwards... silly... the perils of youth

Ya, but the great thing about that amnesia, is that you can keep diving the same crappy old wrecks and still experience that "Wow... Ain't never seen that before!" feeling! Kinda like that move, "Groundhog Day"...