I need an expert ...

[nimoh]

Ok, here goes my try.

Damsel is somewhat petit giving her a naturally low-ish SAC rate despite her being a newbie. She is diving an Al 80 tank with air. She is AOW (so that she is allowed in a Charter to dive a wreck like the Spiegel Grove) newbie with 12 dives under her belt. This is realistic because my instabuddy on my dive to the Spiegel Grove had this certification and experience level. Spiegel Grove sits in 130 ft of water but it is common for divers to stay at 80ft to 100ft for most of the dive.

Hero is diving double Al 80s because that is what he likes. He likes the balance. He just sets up his rig once for two boat dives. No exchanging of tanks during surface interval. And he likes the redundancy. This first dive of the day goes uneventful for 20 mins that Damsel spent at an average of 100 ft. Her computer says she's almost out of NDL time. So she starts to ascend. She saw Hero venting gas from his wing without breaking trim by pulling on the OPV valve. She gives it a try herself as she is ascending and hears a metallic snap following by rapid emptying of her BC and loss of bouyancy. She fell outside the wreck all the way to the 130 ft bottom.

About a year or 2 ago, several manufacturers (Halcyon, Dive Rite, Hog, etc) issued a recall on OPV valves that had a spring that could easily corrode and break. Damsel just happened to dive a BC with one such spring.

Damsel is starting to panic. This brings her normally lowish sac rate of 0.4 cu ft per min to 0.7 cu ft per min for the entire dive (including the non-emergency first 20 mins). Then she finally remembers that she can drop weights. Just as she is getting ready to drop weights Hero's steady hand comes over hers to prevent her from becoming a polaris missile to the surface. Overall Damsel spends a total of 5 additional minutes at 130ft.

Hero turns her body in a position where her bc holds air and starts taking her up. He checks her SPG and decides to put her on his long hose before she actually starts feeling an empty tank. He looks at his computer and SPG and makes some quick calculations. He pulls out a yellow SMB that has a little slate with a small pencil at the top. He writes "Send O2 for 2" and deploys the SMB while Damsel clings to his side (I know people who have had to write "Need O2" on a slate). He makes a 2 min stop at 40ft and another at 30ft. At 30ft a crewman from the boat joins them bringing 2 Al 40 tanks labelled Oxygen. At the 20 ft stop Hero grabs a regulator from an Al 40 and gives it to Damsel. Then Hero grabs one for himself. They do three mins at 20 ft and three more mins at 15 ft before they finally ascend.

Here's an applicable deco schedule with gas consumption figures:

MV-Plan 1.5.2
Settings: GF=30-80 Factors:1.0/1.0 ppH2O=2.041 ftsw ZHL16B
=========================================================
DESC: 99ft for 01:30 [ 2] on Air, SP: 0.0, END: 99ft
DIVE: 99ft for 18:30 [ 20] on Air, SP: 0.0, END: 99ft
DESC:130ft for 00:28 [ 20] on Air, SP: 0.0, END:130ft
DIVE:130ft for 05:00 [ 25] on Air, SP: 0.0, END:130ft
ASC : 50ft for 02:25 [ 28] on Air, SP: 0.0, END: 50ft
DECO: 50ft for 00:06 [ 28] on Air, SP: 0.0, END: 50ft M-Value: 63% [02], GF: 40%
DECO: 40ft for 02:00 [ 30] on Air, SP: 0.0, END: 40ft M-Value: 70% [02], GF: 50%
DECO: 30ft for 02:00 [ 32] on Air, SP: 0.0, END: 30ft M-Value: 75% [02], GF: 60%
DECO: 20ft for 03:00 [ 35] on Oxygen, SP: 0.0, END: 0ft M-Value: 81% [03], GF: 70%
DECO: 10ft for 03:00 [ 38] on Oxygen, SP: 0.0, END: 0ft M-Value: 83% [04], GF: 80%


Gas estimate based on Dive RMV =0.7, deco RMV =0.7cuft/min
Air : 85.5cuft
Oxygen : 6.1cuft
Oxygen Toxicity - OTUs: 29 CNS: 16%

except that carrying an oxygen bottle on a dive with no planned decompression would be unrealistic, and doing the deco on air would take a lot more gas.

However, what if the hero was carrying a pony bottle for just such an emergency, and the accident happens earlier in the dive so the damsel isn't at 99 feet for 18 minutes before going to 130 feet.

 

[Slamfire]

except that carrying an oxygen bottle on a dive with no planned decompression would be unrealistic, and doing the deco on air would take a lot more gas.

However, what if the hero was carrying a pony bottle for just such an emergency?

What if they were diving on a boat like the M/V Spree that also caters to Tech divers? Hero has done some tech dives on the boat and knows that the Skipper keeps a couple of O2 cylinders for eventualities like this. The Skipper will not offload the cylinders from the boat just because they happen to have a couple of Rec dives that day.

I guess Hero could be carrying an O2 bottle for cleanup of tissues or in case he decides to go into deco for a few mins. But then they have to share one single 2nd stage reg between two people and calculate/guesstimate adequate deco time. Or maybe Hero just allows Damsel to complete her deco time on O2 while he breaths backgas air. After Damsel is done with her deco, Hero moves her to the long hose and he takes the O2 for himself. It would probably add 5 more mins of deco time.

 

[nimoh]

What if they were diving on a boat like the M/V Spree that also caters to Tech divers? Hero has done some tech dives on the boat and knows that the Skipper keeps a couple of O2 cylinders for eventualities like this. The Skipper will not offload the cylinders from the boat just because they happen to have a couple of Rec dives that day.

now that sounds exciting. I was thinking that the hero was already in the water among the divers.

Another option is that the hero, upon recognizing that deco will be necessary, writes a note on a slate or wetnotes to drop oxygen bottles to 20 feet and shoots the note up on an smb.

 

[Slamfire]

now that sounds exciting. I was thinking that the hero was already in the water among the divers.

Another option is that the hero, upon recognizing that deco will be necessary, writes a note on a slate or wetnotes to drop oxygen bottles to 20 feet and shoots the note up on an smb.

That was the original idea: "He pulls out a yellow SMB that has a little slate with a small pencil at the top. He writes "Send O2 for 2" and deploys the SMB while Damsel clings to his side (I know people who have had to write "Need O2" on a slate)."

I still like the original idea best

 

[nimoh]

That was the original idea: "He pulls out a yellow SMB that has a little slate with a small pencil at the top. He writes "Send O2 for 2" and deploys the SMB while Damsel clings to his side (I know people who have had to write "Need O2" on a slate)."

I still like the original idea best

sorry, missed that part. You had it right all along

 

[Darnold9999]

Something to consider is passive panic. Someone panicking, who freezes and just watches their spg go to 0. Could let you get her to 130 feet and stay there watching the guage go to 0. Could build up a significant deco obligation Having an internal conversation with herself re got to do something - can't - got to do something - can't.... Have actually seen this happen - so is very possible. As guage goes to 0 , reg gets difficult to breath, no more air - hero shows up and takes control. Could be diving solo, with a pony (or doubles) - then the internal conversation around not enough air for both to do all the deco stops - send a slate up asking for more air knowing the odds are poor that someone will read it and get to you in time - when do you make the decision to skip the deco and surface knowing the bad results. Internal conversation re saving yourself vs two victims holding off until the last minute then someone shows up at the last minute with another tank as a result of the hero sending up the smb. Could choose to swim to a location that might have other divers as a source of air as well. Conversation re swim and use air - or hang and have the air last longer.

Partner is a writer as well. We have these conversations all the time. Mostly guy stuff - cars, guns computers but somtimes other things I know about and she doesn't. And then there are the tough ones - what do guys think when..... ???

Her web site Susan Lyons and Susan Fox - Romance Authors

 

[boulderjohn]

I initially hoped for a longer than 3-5 min safety stop at 15-20 ft, but now wonder if I'll have to make the point of the scene without that. She can be out of air before hero reaches her but not for long. I could possibly have her go unconscious but not for long enough to drown or lose her reg. I can't kill her off.

It is extremely rare for an unconscious diver under water to be revived.

Hero can either take an extra tank with him or people on boat can drop tank/tanks down as needed??

A hero with a good air consumption rate will not need an extra tank to effect a rescue and share air through even a fairly long decompression stop.

It is the timing--how long do I have before he has to notice she is gone, how far she can drop before hero notices, gears up, and gets to her, and brings her up. How many tanks would that take, without either of them dying or needing medical attention.

Are you planning on having her reach a hard bottom and stay there until out of air without figuring out what to do, hoping someone will rescue her? If so, she is a real ditz. But if that is the case, then the hero could start looking for her at any reasonable time depending upon other circumstances. For example, she could drop without anyone noticing her. The rest of the group ascends at the end of the dive, and people realize she is missing. If that is your scenario, then he could suit up then and go in. In that case, if he finds her soon enough (and he will have to), he will have lots of air.

If you do not have a hard bottom and she is sinking into the abyss, then he will have to be on the dive with her, see it happening from a distance, and will have to swim down after her as she descends. Otherwise, he won't catch her.

If she would be out of air before 200ft, what is the farthest she could drop? And what is the most realistic, shortest amount of time she would have to be down to need an extra safety stop and if there are extra stops, what depths should they be and for how long? 15 mins would need a 40 min. stop? What if it was 8-10 mins? What max depth and how long then?

She would only be out of air before 200 feet if she started the descent late in the dive. It does not take long to get to 200 feet.

Consider the real case that happened in Cozumel two years ago. It should give you an idea. Three people decided to do a single tank dive to 300 feet. At that depth, one of them either had severe narcosis (the most common story) or passed out (another version commonly told--but I don't believe it). Whichever happened, she kept descending. Another diver in the group, already close by, swam after her, but did not catch her until 400 feet. The third diver stayed at 300 feet. Once they were together again, they started an ascent. Because of the tremendous rate at which you go through air between 300-400 feet, the two who went to that depth went OOA during the ascent. The three of them made it to the surface by taking turns breathing from the same tank. They could not do any stops. The two deeper divers got severe DCS. She died. He will be paralyzed for life.

 

[dumpsterDiver]

Funny, only time I ever took my wife deep (past 140) were were diving off a desolate wall off crooked island from a boat that knew nothing about diving and we had no oxygen on board. So we are diving 80's with no redundancy and we go down the wall in like 200 ft vis, play around in 100 or so and then decide to go deep. We get down to around 175, I think and I look over at her and she is not controlling her buoyancy. I signal to level off and she adds air to her BC and I see it immediately come out of her Over pressure valve.

She doesn't seem to notice and keeps kicking in the vertical position to stay level with me, but she is clearly pretty negative. I signal to level off and she adds more air and it does nothing and she just stays there kicking and looking stupid. I couldn't believe it! We do one quick deep dive and her BC fails!


She has no clue there is a problem, but I quickly swim over to her, grab her, inflate my BC and do a buoyant ascent back up and I swim us over to the top of the wall that was maybe 90 ft or so. She was kinda agitated that I was man handling her (for no reason) and was cutting our dive short.. We go over on top of a hard bottom and then released her and she was not narced and tried to add more air and this time, she figured out quickly that the BC had failed and was not holding air and we made out ascent.

So it is perfectly reasonable story for a women to be heading down a deep wall, have a problem like that, fail to add air, continue to fall, be separated and distracted and quickly arrive at a depth where the narcosis prevents them for doing much to resolve the problem. The diver would probably resort to animal insincts of just kicking up, but it would burn air, kick in Co2 build up and it is really a perfect scenario for a hero to see her flailing away at depth and then having to chase down to 300 ft or so (something reasonable on air) and drag her up and have her run out of air and may need deco.


The hero could share air, bring her up to 30 feet for deco and then ditch his tank and hand it to her, swim up without it, Scream for help from the boat and have then give him another tank for his own deco. and... if he has lotsa chest hair (like me) there might be no extra tanks with regs on board, so he demands they just give him a raw tank and he descends with it down to her and breaths from the valve. then when she runs out of air in his tank,, he checks her computer, sees more deco is needed and then takes the reg off his tank, switches it to his newer tank, and they continue the deco together. LOL Hey is could happen... and her bikini top COULD have been pulled off in the frantic scramble, in the narcotic haze of 300 feet..

 

[Subcooled]

No no. It's not the equipment. It's the failing mind that kills. And I Do Know. Happy to be alive. First. Lets take a lake diver. No experience on the sea. Attaches a drysuit inflator hose and throws up. Yes. Sea sick. Jumps in. Swims to buoy. Hose comes loose. Doesnt detect. Buddies dive. Waves. Lagging behind. A quick dive. "It was attached". 20 metres down and cant move. The drysuit squeezes,immobilizes. Only the wrist can be moved to signal distress. 50m of water. Poor visibility. My buddy was aware and I'm alive.

Sent from my GT-S7710 using Tapatalk

---------- Post added October 29th, 2013 at 08:04 PM ----------

You should concentrate on distractions, sea sickness, buddy pressure, uncertainty, beeing afraid of the dark (or the depth). Deco is not relevant. Rec diver sinking and then requiring a few mins of deco... Nothing a chamber would not fix. Its the mind that kills. And that will give you a lot to write about.

Sent from my GT-S7710 using Tapatalk

 

[rx7diver]

The problem actually is air supply. The hero can catch the woman and arrest her descent before she runs out of air, but the problem is the two divers do not have enough gas between them for both to ascend directly to the surface, both breathing normally.

So, the hero quickly convinces her to drown herself. (She trusts him implicitly, and he holds her tenderly while she proceeds to drown herself.) After a brief, dramatic pause, the hero ascends with her, breathing off of her tank until it's empty, and then off of his own until it, too, is empty. The last several hundred feet he manages as an emergency swimming ascent, while still surfacing the woman.

The hero is careful to keep her airway open during the whole damned drowned ascent.

When they *dramatically* broach the surface, the hero has the good fortune to immediately find appropriate flotsam to drag the woman upon, and proceeds to resuscitate her, all the while imploring her, screaming at her, to "Live! Live!! Live! Damn it, LIVE!" You see, she is his ex-wife, whom he has never really stopped loving, and he still wears his titanium wedding band as proof...

Wait ... this reads familiar ... somehow ...

Safe Diving,

rx7diver