47 replies to this topic

[PerroneFord]

Those divers who chose to dive walls, or offshore sites in places where the shelf drops away, are ALL diving mixes that become toxic before they could get to a bottom. I was incorrect to say all.

[PerroneFord]

3. When my dive buddy realized his computer was not with him, he should have thumbed the dive. Period. In his absence of doing that, I should have done it myself.

This one is a stickler for many divers. Some say you can both dive a computer IF you stay above the diver with a computer. Others say 'no way not ever'. I know I've been the diver before that didn't have my computer and I've been with a diver before that did have a computer.

Perhaps the decision is more contingent on whether you KNOW the dive buddy and how well. How extreme the dive is...this dive was deep therefore less room for error. Diving on one of the Florida reefs is entirely different.

Knowing what you know now you will probably make a different decision next time...but after spending all the time and effort and money to make a trip...people rarely want to lose a dive for any reasons...even a good one.

Quite frankly, I didn't care that he did or did not have a computer. I could have given him mine, and used my depth guage and the watch on my wrist as I am very comfortable doing that. The REAL problem was that he was RELIANT upon a computer. He had done no planning that would have kept him safe if his computer failed. It was obvious he was somewhat flustered at not having it. He guessed rightly that he had left it in his suitcase. For me, leaving my computer at home would have barely been worth mentioning.

If I venture out again on a dive that approachs NDL, with a diver who is uncomfortable formulating plans or working a table to derive a backup plan, I will call the dive.

[vettenorlando]

3. When my dive buddy realized his computer was not with him, he should have thumbed the dive. Period. In his absence of doing that, I should have done it myself.

This one is a stickler for many divers. Some say you can both dive a computer IF you stay above the diver with a computer. Others say 'no way not ever'. I know I've been the diver before that didn't have my computer and I've been with a diver before that did have a computer.

Perhaps the decision is more contingent on whether you KNOW the dive buddy and how well. How extreme the dive is...this dive was deep therefore less room for error. Diving on one of the Florida reefs is entirely different.

Knowing what you know now you will probably make a different decision next time...but after spending all the time and effort and money to make a trip...people rarely want to lose a dive for any reasons...even a good one.

Quite frankly, I didn't care that he did or did not have a computer. I could have given him mine, and used my depth guage and the watch on my wrist as I am very comfortable doing that. The REAL problem was that he was RELIANT upon a computer. He had done no planning that would have kept him safe if his computer failed. It was obvious he was somewhat flustered at not having it. He guessed rightly that he had left it in his suitcase. For me, leaving my computer at home would have barely been worth mentioning.

If I venture out again on a dive that approachs NDL, with a diver who is uncomfortable formulating plans or working a table to derive a backup plan, I will call the dive.

OK So I don't normally post except for when I am posting on a trip that I am going on... But this is a great post with great responses... Kamala, I think you know this about me already, I am one of those ultra conservative divers and I do not believe in diving another person's computer... EVER... To me the rule of diving above the person with the computer is a terrible rule. If you have nothing at all to give you your depth, well its just silly to get in the water. My answer to the problem... dive charts... I have two computers that I dive with just incase one breaks or batteries or whatever... but I ALWAYS have my dive charts with me on the boat in case both die and I need to use them. Accidents happen when people do silly things... i'd much rather not dive than get myself in a bad situation. Diving has enough risk in it already, why add more than you have to? Even the technical divers that are out there... sure they know the risks of what they do, but generally they are always calculated risks.

Great lessons learned from this... thanks for putting it out there...

[Walter]

Those divers who chose to dive walls, or offshore sites in places where the shelf drops away, are ALL diving mixes that become toxic before they could get to a bottom. I was incorrect to say all.

I plan my mix to reach the hard bottom. When I can't reach the hard bottom, I'll dive air. I can go deeper in an emergency on air than I can on EAN.

[Walter]

I am one of those ultra conservative divers and I do not believe in diving another person's computer... EVER... To me the rule of diving above the person with the computer is a terrible rule.

I don't see that as ultra conservative at all. It's a safety rule that everyone should take to heart. If I don't have a computer, I'll stick with tables. If another diver doesn't have a computer, they won't be relying on mine. It's way too dangerous to even consider diving like that.

[PerroneFord]

I plan my mix to reach the hard bottom. When I can't reach the hard bottom, I'll dive air. I can go deeper in an emergency on air than I can on EAN.

This is a bit ambiguous. Reach it how? Reach it inside 1.4pp? Reach it below 1.6, reach it at 1.0pp?

[Walter]

Not at all ambiguous, merely not as detailed as you would have liked. If I can reach the bottom at a pp of 1.6 atm of O2 or less on EAN, I'll use EAN. If not, I'll stick with air.

[ScubaDadMiami]

There was a time when I would have made this dive on EANx 32. These days, I would not.

On the other hand, remember that CNS oxygen toxicity is based on exposure doses that comprise time and PPO2 factors. So, if someone gave me a chance to dive to 130 feet on EANx 32 for 20 minutes, it is not out of the realm of possibility for me to consider making that dive even these days. However, I would not purposely plan such an exposure if possible to avoid it.

It is when you get beyond a partial pressure of 1.6 that CNS tox hits become too unpredictable to consider doing limited time exposures, thinking that such a short exposure is safe. So, I would not do a PPO2 of 1.8 for even ten minutes.

Again, my choice these days is to keep my bottom PPO2 at about 1.0, and then I bump it up to 1.25 or so for deco. I just spend a little more time doing the deco stops, and I am okay with this.

Personally, I predict that the O2 eposure limits of present will be reduced in the future (especially for CCR dives, which many think are okay at up to 1.4 even for fairly long exposures). I prefer to be a trend setter in that regard.

[6Gill]

There was a time when I would have made this dive on EANx 32. These days, I would not.

On the other hand, remember that CNS oxygen toxicity is based on exposure doses that comprise time and PPO2 factors. So, if someone gave me a chance to dive to 130 feet on EANx 32 for 20 minutes, it is not out of the realm of possibility for me to consider making that dive even these days. However, I would not purposely plan such an exposure if possible to avoid it.

It is when you get beyond a partial pressure of 1.6 that CNS tox hits become too unpredictable to consider doing limited time exposures, thinking that such a short exposure is safe. So, I would not do a PPO2 of 1.8 for even ten minutes.

Again, my choice these days is to keep my bottom PPO2 at about 1.0, and then I bump it up to 1.25 or so for deco. I just spend a little more time doing the deco stops, and I am okay with this.

Personally, I predict that the O2 eposure limits of present will be reduced in the future (especially for CCR dives, which many think are okay at up to 1.4 even for fairly long exposures). I prefer to be a trend setter in that regard.

There was a time that 50ft on 100% O2 rebreathers was common.Then the time 1.6 was the norm...

[Diverbrian]

Actually if I intend to drop to where air is at 1.4 PO2, I am far more comfortable with mix.

Having said that, personally I would have chosen differently for this dive. I do these profiles in the Great Lakes quite a bit. I don't use more than twenty-eight percent oxygen in that type of profile due to the cold and working part of the dive taking another two tenths off of my acceptable risk MOD for a working portion of a dive. The max (1.6) is for at rest on the deco line or chasing someone if I HAVE to do that.

But, also that is Perrone's decision. If he wants to get more NDL with the possibility of a hotter mix if something bad happened, that wouldn't be a terrible decision. It simply isn't the one that I would make and there is nothing wrong with that in my book.

The computer issue: My buddies have it put them simply. We all have at least one timing device/depth gauge. If not, we don't do the dive or I don't do the dive with them. I have no issue with telling the buddy that they can find:

1) another buddy

or

2) a timing device and depth gauge (normally would be in the form of someone's spare computer)

As to following one diver's plan using that timing device and depth gauge, as long as both understand the plan, I don't see a problem with that.

[Walter]

Actually if I intend to drop to where air is at 1.4 PO2, I am far more comfortable with mix.

No arguments, but the rub comes when you aren't intending to go that deep, but there's an emergency such as a narced diver heading down. I'll go after them on air, but not on EAN.

[WreckWench]

Actually if I intend to drop to where air is at 1.4 PO2, I am far more comfortable with mix.

No arguments, but the rub comes when you aren't intending to go that deep, but there's an emergency such as a narced diver heading down. I'll go after them on air, but not on EAN.

True dive professionals in the 'assistance' mode think this way. Its in their training and their nature. They will ALWAYS plan for the worst case scenario so that when others fail to plan that THEY are ready to step in and help.

Thank you for reminding us of this valuable lesson.

[gcbryan]

We can dive together some time. I've got class in a week, so that takes care of this month. Maybe in September.

I'm not doing the Oriskany again until I can do it on Trimix.

Perrone, just a question about this statement. You're not saying that the main problem with your current trip was that you weren't doing it on Trimix are you? I'm guessing your point here is that you don't want to go back unless you can go deeper and you don't want to do that without Trimix.

You also mentioned that you could have given your buddy your computer and that your main problem with him was that he wasn't comfortable planning the dive other than to use his computer and that next time you would cancel such a dive. Why? If you have a good plan and your buddy is ok with it why cancel the dive?

I understand that the main point is don't go diving with a buddy you aren't comfortable with. I think with your current trip I would have donated the computer and stuck to my plan. On the surface interval I would have asked my buddy why he followed the captain rather than me and I would have given him a chance to do a better job on the second dive. If you had a bad feeling about the second dive or weren't feeling well then you would still have to cancel of course. Calling a dive for whatever reason when your gut feeling is to do so is the right thing to do of course.

It's an interesting scenario you layed out and I would just be interested in your feedback.

Thanks.

[PerroneFord]

Perrone, just a question about this statement. You're not saying that the main problem with your current trip was that you weren't doing it on Trimix are you? I'm guessing your point here is that you don't want to go back unless you can go deeper and you don't want to do that without Trimix.

With associated hotel and trave costs, the Oriskany trip would cost me about $250. I had intended to dive it for my Normoxic class. I got an opportunity to do it sooner, without the hotel costs, and decided to dive it. I really would have preferred to be on 21/35 for this dive, but could not. So I will refrain from spending $250 again to dive to 80-100ft.

You also mentioned that you could have given your buddy your computer and that your main problem with him was that he wasn't comfortable planning the dive other than to use his computer and that next time you would cancel such a dive. Why? If you have a good plan and your buddy is ok with it why cancel the dive?

My issue with my buddy, was that he was unfamiliar with dive planning. On most dives that would not be an issue. But with a deeper dive such as this (at least deep for me), I want as many things to go right as possible. If my buddy would have discovered that his computer was not operational under water, I have no idea how he would have proeeded. 3 minutes before splashing was not the right time to be finding out. While my plan might have been good.. it was *MY* plan, not OUR plan. I have little interest in doing anything more than a shallow splash unless all members on the team (or buddy pair) have understood the dive plan, and have agreed to it. Putting a computer on someone does not constitute a "dive plan" in my book.

I understand that the main point is don't go diving with a buddy you aren't comfortable with. I think with your current trip I would have donated the computer and stuck to my plan. On the surface interval I would have asked my buddy why he followed the captain rather than me and I would have given him a chance to do a better job on the second dive. If you had a bad feeling about the second dive or weren't feeling well then you would still have to cancel of course. Calling a dive for whatever reason when your gut feeling is to do so is the right thing to do of course.

There were a number of things I could have done differently, or perhaps better, on this dive outing. Sometimes you have to take an appraisal of the situation, your dive partner, and other factors, and make your best guess. In this case, I felt discretion was the better part of valor, and I chose to stay on the boat and let my dive buddy partner with the captain for his second dive. I got to see the ship, my dive partner got in two dives, and everyone got back aboard safely. Mission accomplished.

[gcbryan]

Thanks Perrone. Teaming up with the right buddy is half the battle in diving in my opinion.

Edited by gcbryan, 17 August 2006 - 12:41 PM.