Would anyone like to dive Devil's Throat?

[uncfnp]

If emergency happens? Then what?

Let them sink?

Risk rescue and pass out?

Valid question. Are you my dive buddy? If you are my dive buddy I know your skill, health and tolerance to this depth. And that you carry a pony. The risk of an emergency right at that moment approaches zero. But yes, if I can intervene I am comfortable with that risk.

If you are not my dive buddy I would have to consider many factors before i act.

 

[Hatul]

I've done it twice--once with Aldora and once with Blue Angel, and it's a great dive. It gets dark so you need a light even if you keep it off, just in case. Ironically our dive with Blue Angel was longer than that with Aldora, in spite of the difference in tanks. Another nice dive in the same area and depth is the Cathedral. If you're experienced you'll enjoy both dives.

 

[Joneill]

“Proud” ?, not particularly since I was simply giving statistics for a common recreational dive for Cozumel.

As for conservative computer, I was referring to the computer algorithm. The limiting factor for my dive. The PO2 is set by myself and is not generally consider conservative. I did not need nor even look at my PO2 on the computer since I knew before the dive the dive plan. Fortunately my dc has no audible alarms.

OK - proud was likely the wrong word - maybe indifferent? So, is diving to 134 feet on Nitrox 32 common in Cozumel. I ask as doing that with most Ops I’ve dived with (admittedly, I’ve never been to Cozumel) would put an end to your diving for the rest of the day.

I guess I struggle with the concept of a conservative algorithm being the limiting factor for your dive if, at the same time, you are going way outside of anything conservative by diving beyond a PPO2 of 1.6?

As I said, dive as you like - I just like to understand people’s thought processes when they dive outside of recommended norms as it helps me make more informed decisions on my own diving. No malice intended!

 

[divezonescuba]

As a single 1.4 / 1.6 data point, I thought I would mention the following.

it is established that everyone has a different tolerence. Mine is 1.6 under working conditions, but not under deco.

I found this out early in my technical diving career on an ascent where I switched to x32 at 110. A problem arose after the switch and as I was very slightly negative I started to drift slowly down while I addressed the problem. I was at 135 (1.6) when I began not to see properly (visual disturbances) and I became very angry (irritability).

Immediately recognizing the classic oxygen toxicity VENTID symptoms, I switched back to my bottom gas, x17/20. Within just a few minutes, the symptoms completely disappeared. I stayed on the bottom gas for another 10 minutes while slowly ascending prior to switching back to the x32.

Most agencies seem to say that you may not necessarily or are unlikely to experience symptoms prior to a seizure. I believe that I was lucky that I did.

On the other hand, I have done some extended deco on x100 at 1.6 and have never experienced any issues.

 

[AdivingBel]

LOL... @uncfnp, thank you for your informative posts...and your patience. It's appreciated.

 

[Soloist]

I believe the hype surrounding Devil’s Throat is a bit over the top. It is an extended overhead dive with an exit exceeding 120 feet, but it’s certainly not an “extreme” dive. There are numerous exit points, no current and the heavy sand eliminates silt outs. I was anticipating something much more challenging, but it was very easy to video the entire dive holding a two handle tray. Moreover, I requested 28% for this dive (received 21%), however, I would have been perfectly comfortable diving the 32% my buddy was diving.

 

[divezonescuba]

There was a study done some time ago, somebody correct me if I don’t get it right.

it said something to the effect that competent people have a tendency to underestimate the difficulty of complex tasks while incompetent people have a tendency to overestimate the difficulty of the same tasks.

 

[uncfnp]

OK - proud was likely the wrong word - maybe indifferent? So, is diving to 134 feet on Nitrox 32 common in Cozumel. I ask as doing that with most Ops I’ve dived with (admittedly, I’ve never been to Cozumel) would put an end to your diving for the rest of the day.

I guess I struggle with the concept of a conservative algorithm being the limiting factor for your dive if, at the same time, you are going way outside of anything conservative by diving beyond a PPO2 of 1.6?

As I said, dive as you like - I just like to understand people’s thought processes when they dive outside of recommended norms as it helps me make more informed decisions on my own diving. No malice intended!

No problem.

Indifference is not the right word either. I assure you much thought went into my choices. My concern for the dive was not an extremely brief high PO2 but rather my nitrogen load. Diving a highish PO2 is conservative from a DCS perspective.

As to whether or not 32 on DT is common in Coz, I am not an expert but I can say my personal experience is that it is not uncommon. And I know from other posts on SB that it is offered for this dive by several shops including one of the largest ops on island.

 

[ggunn]

Been there, done that. I'm glad I did it to see what the fuss is about; it was OK but not something I'm likely to do again.

 

[ChuckP]

The first deep dip (black line) is the Cathedral, the second deep dip is one pass from West to East at Devils Throat and exiting thru the deep exit. The green line is PO2, which spiked at the exit.

If your diving air, exit however you want, drag your belly in the sand and see high 130's on your computer - yea, show your friends!!!!

If you dive 32% - use your head and exit high. You can easily exit that opening in the mid 120's which is a PO2 of 1.5, less than the old standards of 1.6 but higher very briefly than the current 1.4 recommendation.

For that matter, you can still take the downward tunnel and go out the exit before the deep one which is 90 something I think....

Here's today's dive, lead by super Dario. We dropped in and did the Devils Throat formation only which is shown, we ended in Columbia deep but this shows you a simple 25 minute dive on 32% at that site will put an average conservative setting (45/80) into deco which cleared on the way over to Columbia (realize this deco obligation was 1 minute, shorter than a safety stop). This dive covered most of the cave structure, weaving back and forth thru the formation - there is one area I know of that he didn't take us thru as the clearance is pretty tight for backmount tanks. Doing that portion of the dive on air would give you roughly 7 extra minutes of deco.

I purposely exited the deep exit lazy thru the center and still was at 129' or a PO2 of 1.6, again only momentarily.

For the whole cave exploration and exit portion of the dive, I used about 1400psi of a HP120 which is just under 50 cuft of gas or about 1900psi on an AL80 - I probably do have better than average air consumption but yes, you could do a portion of that formation easily on an AL80 but you need good if not great air consumption and it'll be a short dive.