Can someone analyze this incident please?

[Notso_Ken]

Yes, it is very possible to have that much variation between computers.

What you could have done differently was to plan your dive. It appears you did nothing to compare expected bottom times between the two of you given probably different air consumption rates, and the different size tanks.


Ken

I was doing a 100 ft plus dive on a wreck this Friday and got paired up with this other diver. Through out the dive we were fairly close to each other, diving a similar profile but then my tank started to run low as it was an AL 80 and we swam towards the end where the anchor line was. I swam my way up from sand towards the anchor line while she swam parallel to the floor. When we got to the anchor line I was hanging to it 15 feet higher than her. I started moving up the anchor line for my first deco stop but it seemed as if her computer was asking her to do a safety stop much earlier and deeper than mine was. In my training we were taught to stay close to the buddy but I was diving an AL-80 and she was wearing a bigger tank. If I had stuck with her at that depth I would have pushed it on gas. So while keeping her in view I rose up the rope until my computer showed my safety stop which was much higher than where she was hanging. Even when my stop was over I noticed that hers was not. I dive a Suunto Gecko which is a very conservative computer. I was thinking why the hell would she not come up? Is everything ok? I used a sign signal to which she gve me a thumbs up but still wont come. I prolonged my safety stop a few minutes more just so that she could climb up the rope and meet me. By the time we came out I was almost empty on gas.

Later on I was thinking, what could I have done differently? I mean firstly is it possible that two dive computers would show this much of variation in ascent that following them would cause buddy separation of tens of feet? Secondly if that happens to you listen to your computer and abandon your buddy or do you ignore your computer and stick with your buddy?

 

[CAPTAIN SINBAD]

Sorry for the mistake folks. This was a recreational dive not a decompression dive. I did not violate the rule of the thirds but if I had made a point to stay with my buddy then it would have resulted in that violation. Sorry for the mistake. the correct word in this situation is a safety stop not decompression stop.

 

[Scott]

I prolonged my safety stop a few minutes more just so that she could climb up the rope and meet me. By the time we came out I was almost empty on gas.

I did not violate the rule of the thirds but if I had made a point to stay with my buddy then it would have resulted in that violation.

If your buddy arrived at your stop depth and was suddenly OOA, would you have had enough gas to get both of you to the surface?

 

[Mr Carcharodon]

In the statistics DAN has collected fatalities due to running out of gas far out number fatalities from DCS (maybe by 40:1 if memory serves). But dive computers are set up to get you to focus on the relatively less risky issue. That is not to say you should ignore their guidelines but if you are trading off running out of gas or omitting a few minutes of a safety stop getting out of the water while you can still breath takes priority. Since different computers can spit out widely different numbers it is hard to see how you could have fully anticipated what they would do. That is especially true for the other persons computer which you likely had no prior knowledge of. I do not care much for using computers for just this reason. Pre-dive planning where the two of you go through turn pressure, rock bottom(s), deco limits, and the ascent plan before hitting the water would have helped a lot. That is a lot to do with an insta-buddy but it does make the dive more predictable.

 

[CAPTAIN SINBAD]

If your buddy arrived at your stop depth and was suddenly OOA, would you have had enough gas to get both of you to the surface?

I waited for her at 15 ft and she met up with me after my own safety stop was over and while I was only hanging there waiting for her. I could have exited the water but since I was only 15 ft I thought Id hang some more. At 15 ft, It takes a long time to exhaust a tank and even if it is exhausted you can break the surface with ease. It was not a near death experience by any means but I wantd to know what do other people do? Do you guys jut follow your computers and surface abandoning your buddies or do you stick with your buddy abandoning your computers?

 

[DandyDon]

It's difficult to discuss being a better diver when you're getting beat up so huh? So encouraging.

It does help to use correct terms in discussions here as well as in your predive discussion and planning. So no one planned or went Deco, cool. I once was on a boat with a physician who called his back gas Oxygen, me hoping he would keep the differences straight in an emergency.

Yeah, make sure you can surface safely whatever that takes. It's also important to stay with your buddy and take care of that responsibility if possible, but I have had buds refuse to ascend with me because I'm not as good on air. I won't dive with them again. The conflict on computers makes for an interesting challenge and sometimes there is no right answer, just your best effort. Boat pick pairs can be challenging to be sure. Just try to not screw up.

 

[TSandM]

Do you guys jut follow your computers and surface abandoning your buddies or do you stick with your buddy abandoning your computers?

In general, if you are going to dive computers, and buddies have different ones, you dive the most conservative computer -- that means you follow the most restrictive no deco limits, and do the stops called for by the computer that wants more deco time. But you have run into one of the issues with doing that -- you can't do stops you don't have the gas to do.

You said you did not "violate the rule of thirds". Can you explain to me what you mean by that? Did you end the dive with one third of the gas you started with? Because, in that case, you should have had PLENTY of gas to stay with your buddy and do the stops her computer was calling for.

 

[Codiak]

Do you guys jut follow your computers and surface abandoning your buddies or do you stick with your buddy abandoning your computers?

If you are diving with a buddy, then stick with them as long as it's not life threatening.

Deep stops are not practiced by a lot of divers, in OW training they were a foot note. If your buddy intended to use them that should have been discussed pre dive.

That said, diving with multi computer algo isn't brain surgery. Stick with the most conservative and stick to your buddy. Remeber Safety stops are not mandatory, if there really is a low gas sitrep just continue to the surface in a controlled manner as a BUDDY Pair.

If you don't want to stick with a buddy then plan and prepare for solo diving.

 

[Hatul]

The rule of 3rds comes from cave diving. In non deco open water diving we don't normally follow it. The usual rule is to come up with around 700 psi. If you have to buddy breathe you can just skip the safety stop if low on air.

If you do follow the 3rd rule with a single tank, you'd turn back at more than 2000 psi which makes for very short dive.

Adam

 

[Codiak]

It's difficult to discuss being a better diver when you're getting beat up so huh? So encouraging.
up.

Don,
I don't see anywhere in this thread he got beat up. He asked for feedback, poorly described the situation and misused common diving terms. If anything, the replies are gentle for SB. If anyone truly believed he was in deco he would have been blistered, same if he'd actually had an OOA situation.

Most of the posts point to the failure point of this dive, like most it occurred before either diver hit the water.