Would anyone like to dive Devil's Throat?

[rob.mwpropane]

From entry to exit at 134 feet was roughly 5 1/2 minutes.

I dive a very conservative computer and only got into about 2 minutes deco. And that was only after doing the second swimthrough often done after DT. I think it is cathedral?

And yes, I dove it on an 80 cf with 32 nitrox. Total dive time was 40 minutes and I exited the water with 1800 cf in my tank.

Edit: I thought something didn't look quite right. Got my numbers reversed. Back on boat with 1200 psi. Sorry.

I breath more when I'm sitting at my desk dreaming about diving,..let alone actually diving

 

[Joneill]

Hey Joneill. You are absolutely correct that many agencies now teach mod of 1.4 and some instructors teach it as an absolute with immediate consequences when crossed. I was actually taught 1.4 to 1.6 and the rationale for each choice. Like my instructor I choose to dive 1.5 though I rarely get near this. For this dive I only exceeded 1.5 for 2 minutes and my max of 1.6 for about 20 seconds and only that long because I kept a leisurely pace and paused to enjoy the exit to blue water.

MOD for DT has been the subject of several discussions on SB and part of some interesting threads. It might be worth doing a search on SB and reading a bit more on this.

And not sure why you said I did not follow my computer. I actually followed all its requirements and completed my deco as well as throwing in a bit more time at the safety stop. Here again there are several thoughtful and informative threads on something some times referred to as “ lite deco. “

(SB disclaimer - I do have the training and experience to make an informed choice on my dives)

Just to be clear, I'm assuming we are talking Rec OC diving here? I understand that that there is not necessarily any immediate repercussion to crossing over the PPO2 recommended max of 1.4 as it is based on theory and is quite conservative. Ultimately, it a personal decision each diver needs to make, but planned diving beyond PPO2 of 1.6 for other than resting deco is outside of the recommendations of all of the major agencies as far as I know.

The not following computer comment was 2 part:

• Diving to a PO2 of 1.63 on a "very conservative" computer doesn't seem to be conservative at all to me?
• I would have expected your computer to be warning you that you had exceeded your MOD unless you set it's PPO2 limit even higher than 1.6?

Again, dive as you like - I was just pointing out that what you seemed proud of was beyond the recommended norms of the major training agencies.

 

[NDL_Diver]

Since Aldora fills there own tanks, why not get a special DT mix of 30% or 28%?

At 30% MOD at 1.4 ata is 121'; 1.6 ata is 143'
At 28% MOD at 1.4 ata is 132'; 1.6 ata is 156' "edit to correct depth"

 

[SJT1961]

Not if you hold your breathe and just exhale bubbles while at depth! You take one deep breath at 111', once you get to the exit, you exhale slowly till you're back at 111' .

@ChuckP: Not sure what you are trying to say here. You seem to be implying that because you are holding your breath and not inhaling anymore from your reg that your PO2 is not increasing as you descend. If that's what you are saying then I don't believe that's correct. There are two forces at work here. Your PO2 will increase due to descent whether or not you inhale any more gas. And, your PO2 will decrease due to consumption of O2 due to metabolism and work. If you descend quickly enough your PO2 will certainly rise.

 

[uncfnp]

Just to be clear, I'm assuming we are talking Rec OC diving here? I understand that that there is not necessarily any immediate repercussion to crossing over the PPO2 recommended max of 1.4 as it is based on theory and is quite conservative. Ultimately, it a personal decision each diver needs to make, but planned diving beyond PPO2 of 1.6 for other than resting deco is outside of the recommendations of all of the major agencies as far as I know.

The not following computer comment was 2 part:

• Diving to a PO2 of 1.63 on a "very conservative" computer doesn't seem to be conservative at all to me?
• I would have expected your computer to be warning you that you had exceeded your MOD unless you set it's PPO2 limit even higher than 1.6?

Again, dive as you like - I was just pointing out that what you seemed proud of was beyond the recommended norms of the major training agencies.

“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.

 

[NDL_Diver]

Well the point of using 1.4 is so you can go deeper in an emergency. If you are already at or over 1.6 you have no room to rescue someone who is narced up and heading down.

 

[NDL_Diver]

Dave is correct it has a time factor, but they also found that people are different.

Convulsions happen rapidly with no (little) warning.

A dive shop could open themselves up to lawsuits if a diving accident happens on a dive that was PLANNED to be outside limits of a MOD.

 

[rick00001967]

regardless of how comfortable a diver feels when planing a dive to 1.6, there simply is no reason for it. adjust your mix (as was suggested above) and always plan conservative in case the unexpected happens. and i totally agree with the above statement. furthermore, any shop that would knowingly allow any diver to plan and execute a dive beyond what every agency teaches should be avoided and be reported to which ever agency they represent imho. the "i do it all the time and nothing bad ever happened to me" argument is not the standard we should be following.

 

[uncfnp]

Dave is correct it has a time factor, but they also found that people are different.

Convulsions happen rapidly with no (little) warning.

A dive shop could open themselves up to lawsuits if a diving accident happens on a dive that was PLANNED to be outside limits of a MOD.

Of course I can’t speak for the shops but while best mix blends are not readily available in Cozumel all ops offer 21% and anyone not comfortable with 32 always has that option. Ultimately the choice of gas is the diver’s not the shop. But then there is an increased risk of the inattentive diver going into deco and possibly OOA trying to clear deco or blowing a deco stop.

All diving carries risk. It is up to the diver to choose the best way for them to mitigate this risk. There is always the option not to do any dive you feel too risky or not qualified to do,

One might also say that shops should not take any diver not certified for overhead or for deep on this dive. I think 20 seconds of 1.63 is the least of the significant factors for planning this dive,

 

[NDL_Diver]

If emergency happens? Then what?

Let them sink?

Risk rescue and pass out?