Interesting Deco question..

[WheelerDealer]

I was in a D/FW area dive shop last weekend where the topic of the day between two local tech divers was a situation that had occured on one of the guys recent trip to Somewhere on or near Bikini Atoll. As I understand it there were four divers in the water who all began the dive together, and three of them were on trimix and the fourth was a local DM who was breathing air. The dive was a 180ft dive and at about 15 minutes into the dive the DM who was on air had a first stage failure and was unable to deal with it,(gee I wonder why) so one of the mix divers came over and donated their long hose to him and everyone ultimately surfaced okay after deco. Not being a deco diver myself (yet) I was wondering if the air divers deco plan would have to change because he switched to mix during the dive?? I did not get to here what all of the guys deco schedules were but I did hear them say that the mix guys were carrying EAN32 and 100% O2 for deco and that the air breathing DM was only carrying 100% O2. So, what would be the proper thing to do to get this guy out of the water as safely as possible. Other than telling him to get mix training and quit diving deep air that is. Also, they were talking about how difficult it was to get mix while they were there. Is this a common problem when deep diving around the world?

 

[Bob3]

Bikini is waaaaay the heck out in the middle of nowhere, there isn't anyplace to get helium unless you wanted to pay hundreds of $$ for a fill.
32% nitrox sounds VERY fishy too, because of the depths.
I'd be pretty suspect of a story like that, considering the difficulties in obtaining He that far out in the boonies.
Did ya notice anything smelly sticking to the bottom of your shoes when ya left the place?:tease:

 

[Scuba_Vixen]

While expensive, they do organize well in advance and have their gas for mixing in place. (The Truk trips are the ones harder to get mix to)

The nitrox32 would have been the deep deco mix, some like switching to 32 at at 130', others like 50 at 70' and the O2 , of course at 20'.
A quick spin on Vplanner gives about a 43 min run time for the air diver and 38 for the mix guys. (I assumed 18/45, since that would be a good choice, but it could have been21/35 and Ean32 at 130) Mix deco typically starts deeper than air, and for short dives is longer, but the mix guys had better gasses to deco on, so it cut their time. If the mix guys kept the air guy with them on the way up and thru deco, especially if they shared gas with the Ean32 untill they all got to where the air guy got to his O2, He would have been just fine. (Wouldn't have made much difference if he'd have been on their mix, or his backgas during their stops on 32, a few extra minutes on O2 at 20 and 10, for safety, and he'd be fine)

The thing I'd wonder more about, is why anyone would be at that depth without doubles. A first stage failure would then only be an inconvenience .. the dive still gets immediately aborted, but no cause for high drama, and no life threatening scenario.

I'd love to do Bikini someday myself.

Darlene

 

[WheelerDealer]

The thing I'd wonder more about, is why anyone would be at that depth without doubles. A first stage failure would then only be an inconvenience .. the dive still gets immediately aborted, but no cause for high drama, and no life threatening scenario.

I do not know if he was wearing doubles or not. It was simply stated that he just "froze up" and sort of stopped trying to help himself as he sat there giving the OOA signal.

Bikini is waaaaay the heck out in the middle of nowhere, there isn't anyplace to get helium unless you wanted to pay hundreds of $$ for a fill.

I don't know anything about Bikini Atoll and the logistics of getting mix out there, but I do believe that they were diving mix, and I make a living reading people and wading through bulls#%t everyday so I think I would have known had they been BSing. They did comment several times on what a PITA getting mix out there was. The next time I am in there I will see if I can get more info.

 

[Scuba_Vixen]

for that guy.... "Just Froze" comes from complacency and not having emegency proceedures almost as automatic muscle memory.

That may be one of the blind spots of dive professionals, they do so many dives with no problems, that the "can't happen to me" mode sneaks in.

 

[cornfed]

WheelerDealer once bubbled...
So, what would be the proper thing to do to get this guy out of the water as safely as possible. Other than telling him to get mix training and quit diving deep air that is.

Well... oh, wait... never mind...

 

[Diver0001]

WheelerDealer once bubbled...
I<snip>So, what would be the proper thing to do to get this guy out of the water as safely as possible.
<snip>

Lowest (or this this case "slowest") common denominator.

R..

 

[IndigoBlue]

WheelerDealer once bubbled...
I was in a D/FW area dive shop last weekend where the topic of the day between two local tech divers was a situation that had occured on one of the guys recent trip to Somewhere on or near Bikini Atoll. As I understand it there were four divers in the water who all began the dive together, and three of them were on trimix and the fourth was a local DM who was breathing air. The dive was a 180ft dive and at about 15 minutes into the dive the DM who was on air had a first stage failure and was unable to deal with it,(gee I wonder why) so one of the mix divers came over and donated their long hose to him and everyone ultimately surfaced okay after deco. Not being a deco diver myself (yet) I was wondering if the air divers deco plan would have to change because he switched to mix during the dive?? I did not get to here what all of the guys deco schedules were but I did hear them say that the mix guys were carrying EAN32 and 100% O2 for deco and that the air breathing DM was only carrying 100% O2. So, what would be the proper thing to do to get this guy out of the water as safely as possible. Other than telling him to get mix training and quit diving deep air that is. Also, they were talking about how difficult it was to get mix while they were there. Is this a common problem when deep diving around the world?

I would not take stories like this too seriously. Sounds like just another deep air joke.

If a local D/M was diving a single tank with a single 1st stage reg on it, to 180 ft, and was carrying pure O2 in a deco stage, then he had a huge gap in this emergency/contingency plan from his MOD to 20 ft. He would have needed a bail out bottle, sort of like the CCR divers carry.

 

[Scuba_Vixen]

If it had been a mix diver with a problem coming up on an air schedule. The O2 at 20' was probably a sufrace supplied set up, not uncommon for those trips.

Here's a link to a thread on trips to Bikini for those interested.

http://thedecostop.com/forums/showthread.php?t=1284&highlight=bikini+atol

Hope it was ok to do this, would answer a lot of questions, and it links to the Bikini dives website as well.


Darlene

 

[DepartureDiver]

I was in a D/FW area dive shop last weekend where the topic of the day between two local tech divers was a situation that had occured on one of the guys recent trip to Somewhere on or near Bikini Atoll. As I understand it there were four divers in the water who all began the dive together, and three of them were on trimix and the fourth was a local DM who was breathing air. The dive was a 180ft dive and at about 15 minutes into the dive the DM who was on air had a first stage failure and was unable to deal with it,(gee I wonder why) so one of the mix divers came over and donated their long hose to him and everyone ultimately surfaced okay after deco. Not being a deco diver myself (yet) I was wondering if the air divers deco plan would have to change because he switched to mix during the dive?? I did not get to here what all of the guys deco schedules were but I did hear them say that the mix guys were carrying EAN32 and 100% O2 for deco and that the air breathing DM was only carrying 100% O2. So, what would be the proper thing to do to get this guy out of the water as safely as possible. Other than telling him to get mix training and quit diving deep air that is. Also, they were talking about how difficult it was to get mix while they were there. Is this a common problem when deep diving around the world?

Complicated question ... assuming the story was not a joke, if the diver had been at depth for 15 minutes, he had loaded "some compartments" (if you take that approach) with nitrogen. Now when he switched to trimix, the compartments loaded with nitrogen from the air are now being loaded with helium too resulting in a greater compartment load. So his stops could become complicated and might should be even deeper than the trimix divers' stops.