Rob Stewart and Third Dive

[rjack321]

I've done 2 in the 180-200ft range in a day with a 2-2.5hr SI. I dont do bounces to 200ft at all though so I have no basis to judge the "3rd dive" except that for someone so new to CCRs that seems pretty aggressive.

What were the causes of Sotis struggling on the surface that needed assistance to get back on the boat & Rob passing out on the surface and sinking to the abyss without being noticed by the crew then?

We don't know - but Rob's handset/cells showed a breathable loop the entire time he was on the surface and most of the time he was falling back into the abyss until the loop flooded. While hypoxia seems the most obvious cause, the only evidence says its not.

 

[Protondecay123]

To speak specifically about Rob and Sotis, they had over 2 hours of omitted decompression based on the the algorithm and gas they were diving. Hypoxia wasn’t a problem for them.

Just checking my reading comprehension, 2 hours of OMITTED ( my all caps) decompression? I’m no tech diver but have read that some can get by omitting an hour ( and some can’t) but it’s playing with fire after that. 2 hours? I’ve been wondering about hypercapnia. But maybe DCS? There were some filings about a no -rescue despite Stewart thrashing at the surface for over 3 minutes as well,

 

[RainPilot]

have read that some can get by omitting an hour ( and some can’t) but it’s playing with fire after that

Just to be very clear here, for others reading later: ANY omitted deco is *potentially* lethal, depending on the conservancy of the initial algorithm chosen and the personal gas physiology of the diver concerned. It definitely can't be reduced to a "so many minutes is safe" number.

It might be simpler to look at it as a "percentage omitted" and then look at the results. If I had 30 minutes of deco, and omitted 3-4 minutes I would probably be ok. I use conservative algorithms and for short exposures, single deco dive per day.

That would translate to 10% of my deco omitted. 10% wriggle room seems to me to be reasonable, but that's just a gut feel, no science to back it up. If I had to omit an hour of deco, from a 2 hour total, that, to me, would be very dangerous, unless I was using a ridiculous GF (like 30/30 or even lower GF Hi).

I don't know where the DCS line is for me, but if I skipped an hour of deco under any circumstances I would expect a hit, and a severe one at that. Since I am unaware of where that line is, I also dive conservatively and do everything in my power to complete all deco (and usually a bit more).

 

[hroark2112]

I can not imagine how absolutely miserable I would be if I missed 2 hours of deco. If I were not dead, I might wish I were. I know for me if I do a deep dive(s) and I don't extend my last stop for a minimum of 5-10 minutes on O2, I'm going to have a painful night of skin bends at a minimum.

Sad story, and a very scary one!

 

[tomfcrist]

I know for me if I do a deep dive(s) and I don't extend my last stop for a minimum of 5-10 minutes on O2, I'm going to have a painful night of skin bends at a minimum.

Sounds like you need to dive a different deco profile.

 

[jstrang]

I have no issues doing 2 deepish dives to 200' in a day. I've always tried to double my run time as a SI. So if its a 90minute dive a 3 hour SI, if its a 2 hour dive a 4 hour SI. On a recent technical liveaboard a 4 hour SI was mandatory between dives and to my knowledge there were no issues.

3 dives to 200' - and struggling to untie an anchor on the 3rd... when all you had to do is cut the anchor loose and retrieve it another day.... No thanks.

 

[hroark2112]

Sounds like you need to dive a different deco profile.

That's another option.

I usually dive 30/70 GF and stay at 15-20' for at least 5-10 extra minutes before surfacing on deeper dives. As long as I stick with this, my experience is that I'm OK. Not saying that if I don't do the extra time I'll definitely have problems, but the extra time in the water is almost never a problem for me.

 

[tomfcrist]

That's another option.

I usually dive 30/70 GF and stay at 15-20' for at least 5-10 extra minutes before surfacing on deeper dives. As long as I stick with this, my experience is that I'm OK. Not saying that if I don't do the extra time I'll definitely have problems, but the extra time in the water is almost never a problem for me.

Cool. The other post sounded like if you didn’t do the extra, at a minimum you get skin bends. That’s no bueno for me. I’d definitely change my diving if that were happening.

 

[hroark2112]

Cool. The other post sounded like if you didn’t do the extra, at a minimum you get skin bends. That’s no bueno for me. I’d definitely change my diving if that were happening.

I find it easier to just assume that if I don't dive with a little extra conservancy that I'm going to to hate my life for a few hours. It's just easier to assume than to take chances. Kind of like going to prison...if you can't do the time, don't do the crime.

 

[hroark2112]

I just watched the documentary. I'd be interested to know what the GF they were running that day. I know certain instructors advocate running a 90/90 GF. If that was the case here, that would make me lean more towards DCS as the likely cause.