Preparing for Devil's Throat

[Mossman]

Note that the calculation I did is for TWO divers, not one, and I used the currently recommended ascent rate of 30 fpm. You can certain exceed that, but then you have to ask the question whether planning to compound the problem of being out of gas with a rapid ascent is a reasonable strategy.

I should add that, with the ascent strategy that I was trained to use and WOULD use in such a situation, the rock bottom reserve is much larger, which is one of the reasons I don't do dives like this on a single tank, no matter what size.

Uh, PADI, the biggest, most hugest, gigantic dive training agency teaches 60 fpm. If it's good for PADI, I'm sure it's good for divers running out of air who want to get to the surface without running out of air. As far as I know, this is their currently recommended ascent rate:
(see #7) © Diving Science and Technology

Assuming two divers sharing air is a big assumption. After all, it's highly unlikely someone will run out of air before exiting the throat since it's done at the beginning of the dive. It would have to be a regulator failing closed. And all dives in Cozumel are required to be led by a divemaster who usually has stellar air consumption. Once the dive group is out of the throat, the LOA diver can simply be passed around if necessary.

Calculations are fine and dandy, but they have to be based on realistic scenarios for them to be taken seriously.

 

[DiveNav]

I did the throat few years ago.
What I liked most was ..... the light at the end of the tunnel.
Since I am an Instructor the operator decided to put me at the back of the line ... so I did not see too much inside the tunnel itself ... but I remember I got few kicks on my mask
And yes ... I did the dive on an AL80 (the only tank they had) ... and I came up almost empty.
No, I did not have any buddy to look after. Just myself and my SMB.

Next time I will get an operator that has bigger ... tanks.

Alberto (aka eDiver)

 

[cb5150]

It's not a difficult dive if nothing goes wrong.

Well, Hello Captain Obvious!

 

[drrich2]

First of all, it really doesn't make any difference what dive op you use, there are just a lot of Aldora loyalists on this forum, and the owner does post from time to time. But in the end, it's the same dive and you're the one doing it.

Maybe so, but it won't be the same tank. Very few op.s offer 120 cf tanks, from what I understand; Living Underwater and Aldora are 2 of them, as I understand.

Richard.

 

[vancouverdiver]

Zombiezombie, I dove devils throat a few years ago. It was a lot of fun, but the last half of the dive was in blue water and I didn't see as much as being on a wall. However, based on what you said, and as you are asking, I would suggest you play the conservative card and do other dive sites. Devil's throat will still be there when you have gained more experience. You will enjoy the dive more, see more, and will have a greater ability to deal with issues. Having said that, as others have posted, you need to understand gas management and to have sufficient gas to get 2 divers safely to the surface. You definitely do not want to do this with an al80. If there is a dive op that suggests taking you there with an al80, I would suggest you dive with another dive op. I did it with Living Underwater, they had steel 120's, and they are a good dive op. Others have reported good experiences with Aldora. Keep in mind that Cozumel has a number of great dive sites. Why not dive those on this trip?

 

[halocline]

I'm not sure the gas is the main issue, although it is a big one. At the risk of repeating myself, to me the main issue is being stuck in a long deep swim through with a bunch of divers who may or may not be capable of handling the dive comfortably, and very few of whom have technical dive training or experience. Certainly lots of divers do this dive every day and there are very few fatalities. But, how many unpleasant scenes are there, ranging from someone simply silting everything up to people full on panicking and mugging a nearby diver? I bet those sorts of things, some serious, some just annoying, happen all the time.

Think of it a little like driving in an ice storm in TX. Sure, I can do it, it's all the other knuckleheads on the road I'm worried about!

 

[flots am]

It's not a difficult dive if nothing goes wrong.

Same thing with caves and wrecks . . .

Dives like that are why I bring my sidemount BC for trips. It's a cool dive on an AL80, as long as you bring two of them and a long hose.

I did it on a single tank when I was brand new and didn't know any better. I didn't die, but only by a few hundred PSI.

 

[Ron Lee]

I'm not sure the gas is the main issue, although it is a big one. At the risk of repeating myself, to me the main issue is being stuck in a long deep swim through with a bunch of divers who may or may not be capable of handling the dive comfortably, and very few of whom have technical dive training or experience. Certainly lots of divers do this dive every day and there are very few fatalities. But, how many unpleasant scenes are there, ranging from someone simply silting everything up to people full on panicking and mugging a nearby diver? I bet those sorts of things, some serious, some just annoying, happen all the time.

How many fatalities can be attributed to diving Devil's Throat compared to other dive sites?

Diving this site with Aldora is not "Get out at the lower opening and immediately start your ascent." In the past, it would also include going up in the area that used to have the yellow sponge, then swim over to the next reef to the north. That is about all that I recall. Others may be able to provide a complete dive description.

 

[Dirty-Dog]

Scare tactics aside...
We dove it with Aldora and their HP120s. We dove the throat, came out, moved up and bit and headed over to the cathedral, then surfaced. Lowest on air was me, and I had 750PSI when I got on the boat. No deco, although NDL was certainly the limiting factor on our bottom time. None of the people on the boat (excluding the DM...) were million dive pros. One of them had 40-45 dives at the time. I was tail end and while there was a little silt, it wasn't bad, really. The water moves enough to clear it fairly quickly.
The throat is really just a long swim through, and it doesn't rank on my "dive every Coz trip" list. But if you want to see it, then go for it. Assuming you have reasonable skills, you should be fine.
I do agree with those who say it's not really an AL80 dive, though. With the 120s, if anybody had been LOA, we would have had no difficulty getting the group to the surface.

 

[Gdog]

In 10 yrs of Cozumel diving, have dove the Throat one time. That single time was more than enough for me. Hated it, was a wasted dive in my opinion. But it does seem to be a right of passage dive. However, Lynne's calculations of rock bottom should cause a little pause. Of course the odds are with you that nothing will go wrong; I mean, they go right how many times a day every day of the year for the Devil's Throat divers. But...halfway down the throat you experience equipment failure; or you exit the throat at 130' and you have a reg free-flowing; then do you have enough gas? Does your dive buddy? How willing are you to gamble on either nothing will happen this time, or that your buddy has a lower sac rate than you do and has plenty of gas to share?
If you are willing to gamble, make sure you at least run the calculations yourself, and then make an educated guess for yourself.
Just my two pesos.