What defines technical diving - and how to get there?

[ucfdiver]

"This message is hidden because JeffG is on your ignore list. "

Here is a really good way to clean up loads and loads of meaningless crap from off your P/C screen. Life is short. No time to waste.

JeffG and myself have both made one of the most honorable positions on scubaboard, and that's on nereas' ignore list. If anyone else cares to join us, start making posts using common sense, he gets real torn up over that.

 

[Bismark]

JeffG and myself have both made one of the most honorable positions on scubaboard, and that's on nereas' ignore list. If anyone else cares to join us, start making posts using common sense, he gets real torn up over that.

Welcome to the club. Air seems better here......

 

[Bismark]

Not that it matters but plenty of divers could do a multi-level dive with 140' max depth and 60 min total dive time. If I can do it with a 100 cft, quite a few could do it with 72 cft and have more than 500 psi left over. Some small women I know could easily do it with 63 cft!

I don't think the question is whether you can do a simple descent to 140' and ascent with any of these tanks. If this dive you suggest is not a bounce dive, you may want to become acquainted with the concepts of "rock bottom" or "minimum gas". Moreover, what exactly was your plan if you had a catastrophic failure (extruded tank o-ring, first stage failure, second stage freeflow....) at depth? CESA from 140'? I don't think I could do it....... Or were you planning on sharing your friends 63 cu ft tank? Here are some numbers for you:

Gas used for descent: (assuming a very low SAC of .5 cu ft/min) 4.5 cu ft
5 min at 140': 13 cu ft
1 min at 140' to share gas and sort out problem but now with two people breathing quite a bit faster--SAC now 1.0 cuft per min: 10 cu ft
Ascent with 2 people at 30 ft per min: 30 cu ft
3 min at 15 ft (you were at 140' afterall) for people: 9 cu ft.

Total gas used: 66.5 cu ft......... I believe you started with 63 cuft.......

Which one of you were not breathing for the last few minutes?

This is the reality of your gas plan.

Were you planning on not doing a safety stop after a dive to 140'? Were you planning on a lower emergency SAC rate? Were you planning on no emergency?

I am not trying to cut you down. I am sharing with you the simple physics of the equation. Everyday people do this dive on single AL 80's and have no understanding of the numbers. However, with this awareness, you have to knowingly make some decisions regarding risk. What you chose to do after that is entirely your choice. You and everyone else simply deserve to know what is involved in the risk equation.

Again, this is not an attempt to flame you.

 

[HullBlister]

Great link on Rock Bottom Gas.

Its one of those rules I need to constantly remind myself of so that I adhere to it.

Blister

 

[Thalassamania]

Credit the term "technical diving" to Mike Menduno at aquaCorps. Exactly who coined it, I'm not sure, no one is, but is was one of us at aquaCorps, so give Mike the credit. The concept was that, like technical climbing, there is recognition of the difference between being dependent on skills to being dependent on equipment. That's where the term "technical diving" came from and what it means.

 

[highflowdiver]

OK this has really taken off & this is the 1st chance I've had to respond.
Believe me if I have 32% in my back gas chances are my stage /deco bottles have a stronger mix. So it would be a no go for me. I have no problem with that. Got to live to dive another day. But I'm not a quarry diver.
In the Ocean we go to a shallower site if the primary site is not doable. So gas choices might not be optimal, but will do safely.
I would also never dive to 140ft on a single tank. I don't like bounce diving & if I am not going to be there for at least 30 min, why bother.

Bobby

I agree with everything you have said here. For quarry diving I always bring a
couple of 80s with air and/or light mix with me as well as the deco bottles,, in case I desire to save my backgas or need to power my booster. The issue at a quarry is that below the thermocline the temp is about 42 degrees. So there, it is always the temp. that forces the turn. Either the fingers or the toes or both will make the decision for you. When you come up to where it is warmer you can continue
to dive for as long as you desire. In the middle of winter it is warmer at depth
than nearer the surface. That is a tricky cold dive.
Kal

 

[MauiScubaSteve]

I don't think the question is whether you can do a simple descent to 140' and ascent with any of these tanks. If this dive you suggest is not a bounce dive, you may want to become acquainted with the concepts of "rock bottom" or "minimum gas". Moreover, what exactly was your plan if you had a catastrophic failure (extruded tank o-ring, first stage failure, second stage freeflow....) at depth? CESA from 140'? I don't think I could do it....... Or were you planning on sharing your friends 63 cu ft tank? Here are some numbers for you:Were you planning on no emergency?

.....

What you chose to do after that is entirely your choice. You and everyone else simply deserve to know what is involved in the risk equation.

Again, this is not an attempt to flame you.

If I was worried about flames I wouldn't post threads like this...

http://www.scubaboard.com/forums/hawaii-ohana/243718-molokini-kayak-dive.html

 

[Bismark]

If I was worried about flames I wouldn't opost threads like this...

http://www.scubaboard.com/forums/hawaii-ohana/243718-molokini-kayak-dive.html

Some very cool photos.

Personally, I have no problem with adults making informed choices. I guess you and I simply come from different positions on this and I have no problem with that. My only concern is when lack of understanding and education allows someone to unknowingly make a choice that places them, unknowingly, in harms way. We have a different medical system in our two countries so that even precludes me from my entitlement to having a say in the issue as a taxpayer We just come from different philosophical positions on this diving thing but the world would be pretty boring if everybody agreed with everybody else.

Aloha,

 

[RAD Diver]

Not that it matters but plenty of divers could do a multi-level dive with 140' max depth and 60 min total dive time. If I can do it with a 100 cft, quite a few could do it with 72 cft and have more than 500 psi left over. Some small women I know could easily do it with 63 cft!

I don't remember saying anything about a muti-level dive. Most of the dives I do off the East Coast, most of the time you are at max depth. I guess I should have said safely done. I also said at least 30 min bottom time. Last 1 I did was 60 min Bottom Time.
I also would not be diving with someone with a single 72 or 80 for that matter to these depths. As i would be in doubles & if I can help with an emergency I require my buddy to be able to do the same for me.
But we all make our own choices, just be ready to live (or not) with them.

 

[RAD Diver]

I agree with everything you have said here. For quarry diving I always bring a
couple of 80s with air and/or light mix with me as well as the deco bottles,, in case I desire to save my backgas or need to power my booster. The issue at a quarry is that below the thermocline the temp is about 42 degrees. So there, it is always the temp. that forces the turn. Either the fingers or the toes or both will make the decision for you. When you come up to where it is warmer you can continue
to dive for as long as you desire. In the middle of winter it is warmer at depth
than nearer the surface. That is a tricky cold dive.
Kal

Thats all cool, but my CF-200 with the dry gloves attached 42 is not that bad. We dove Lake Erie last year & that was the bottom temp. never made us quit our dive early.
Off the Mid Atlantic coast we are lucky to get 50+ degrees at depths as shallow as 100fsw, so you can't be a WWW around here & get to the really cool sites that start at 140fsw.