View Full Version : hyperthetical incident
Ok here goes...
I often wonder about incidents and how i would react if it where to happen to me...for warned/planned is forarmed as they say.
So imagine you came across a trapped diver...say at 20M the only way to free this chap is to remove him from his kit...his kit remains trapped so you cant put the casualty back in his kit after.
Obviously you then have to lift the unkitted casualty on your gear..ok no problem so far...but what about his weight belt ?
1.Do you ditch it at depth, with the possibility of him becoming very positive and taking u both to the surface ?
2.Do you bring him up with him still wearing his weight belt and then ditch at the surface, with the possibility of loosing contact with him on the way up and him sinking down again without air....
hmmmmm what would you do ? :)
Nigel Hewitt
25-08-2005, 12:27
Obviously you then have to lift the unkitted casualty on your gear..ok no problem so far...but what about his weight belt ?
3: What about giving it him to hold?
:=Obviously you then have to lift the unkitted casualty on your gear..ok no problem so far...but what about his weight belt ?
3: What about giving it him to hold?
hmmm my problem was to either leave the weightbelt on (having it around the casualty or him actually carrying it is another debate ? maybe )
or to drop it off at depth...im not sure how bouyant a drysuited diver would be without kit or weightbelt at depth..and therefore how much of a bouyancy problem he would cause the rescuer ... ponder ponder...
Nigel Hewitt
25-08-2005, 13:14
>>>Obviously you then have to lift the unkitted casualty on your gear..ok no problem so far...but what about his weight belt ?
>>3: What about giving it him to hold?
>hmmm my problem was to either leave the weightbelt on (having it around the casualty or him actually carrying it is another debate ? maybe )
>or to drop it off at depth...im not sure how bouyant a drysuited diver would be without kit or weightbelt at depth..and therefore how much of a bouyancy problem he would cause the rescuer ... ponder ponder...
Holding the weight belt was suggested to me as a response to trying to do a stop if you felt unsure you would stay fully conscious. I wondered it it could apply here as it makes 'dump weight' a virtually instinctive thing to get back to the surface if they lost you.
I needed 4Kgs on my twinset because it was so negative but 14Kgs with the neutral oxygen rebreather in the same dry suit. So take me out of the twins and I would be frighteningly positive, 10Kgs I assume. With the turtle it is normally all integrated so as a victim I am, in a word, stuffed. I'd prefer to go with the weight on and snap the belt open if I loose you (my buoyancy device) but I'm not going to have enough lead.
It is a quandry....
:=>>>Obviously you then have to lift the unkitted casualty on your gear..ok no problem so far...but what about his weight belt ?
:=>>3: What about giving it him to hold?
:=
:=>hmmm my problem was to either leave the weightbelt on (having it around the casualty or him actually carrying it is another debate ? maybe )
:=>or to drop it off at depth...im not sure how bouyant a drysuited diver would be without kit or weightbelt at depth..and therefore how much of a bouyancy problem he would cause the rescuer ... ponder ponder...
Holding the weight belt was suggested to me as a response to trying to do a stop if you felt unsure you would stay fully conscious. I wondered it it could apply here as it makes 'dump weight' a virtually instinctive thing to get back to the surface if they lost you.
I needed 4Kgs on my twinset because it was so negative but 14Kgs with the neutral oxygen rebreather in the same dry suit. So take me out of the twins and I would be frighteningly positive, 10Kgs I assume. With the turtle it is normally all integrated so as a victim I am, in a word, stuffed. I'd prefer to go with the weight on and snap the belt open if I loose you (my buoyancy device) but I'm not going to have enough lead.
It is a quandry....
hmmm interesting...i must admit my first thought would be to leave the weightbelt in place and make dam sure i got a good hold of them so i didnt lose them on the way up...
Never been anywhere near a rebreather diver and as you say if you dont carry enough lead in the first place there arent may options ...hmmmmmmm... i guess this is one scenario that would be helped by the people who carry ponies side slung like stages...they then could just hand off a pony and even if you become very positive and jet to the surface...at least i dont have to come with you...and you can breath all the way up ....hmmm even more ponder :)
Clodagh Watt
25-08-2005, 14:45
Ok here goes...
I often wonder about incidents and how i would react if it where to happen to me...for warned/planned is forarmed as they say.
So imagine you came across a trapped diver...say at 20M the only way to free this chap is to remove him from his kit...his kit remains trapped so you cant put the casualty back in his kit after.
Obviously you then have to lift the unkitted casualty on your gear..ok no problem so far...but what about his weight belt ?
1.Do you ditch it at depth, with the possibility of him becoming very positive and taking u both to the surface ?
2.Do you bring him up with him still wearing his weight belt and then ditch at the surface, with the possibility of loosing contact with him on the way up and him sinking down again without air....
hmmmmm what would you do ? :)
How about attaching a line on a reel to the weight belt and the kit and handing the reel to the diver before removing the gear. If the diver wasn't panicking, perhaps he could control the ascent by gradually letting out the line
Nigel Hewitt
25-08-2005, 15:09
How about attaching a line on a reel to the weight belt and the kit and handing the reel to the diver before removing the gear. If the diver wasn't panicking, perhaps he could control the ascent by gradually letting out the line
I wondered about this one but my concern is that with several kilos of buoyancy to overcome we are talking about a diver 'hanging' upside down with the suit unable to dump and getting progressively more buoyant as we go up. I can't see a way to make the line feed from the fins end so to speak.
Ok here goes...
I often wonder about incidents and how i would react if it where to happen to me...for warned/planned is forarmed as they say.
So imagine you came across a trapped diver...say at 20M the only way to free this chap is to remove him from his kit...his kit remains trapped so you cant put the casualty back in his kit after.
Obviously you then have to lift the unkitted casualty on your gear..ok no problem so far...but what about his weight belt ?
1.Do you ditch it at depth, with the possibility of him becoming very positive and taking u both to the surface ?
2.Do you bring him up with him still wearing his weight belt and then ditch at the surface, with the possibility of loosing contact with him on the way up and him sinking down again without air....
hmmmmm what would you do ? :)
Easy awnser.
On a standard assisted ascent you are taught to share air and
lift using your BC. The scenario works on the premise that if
this guy is OOA chances are that there wont be any for his BC
as well.
Take away the cylinder and BC and ignoring any residual air
trapped in the BC, he will be lighter even with the w/belt.
So you can (as before) do a standard ascent. Soon as you reach
the surface you then dump the weightbelt a hes
bouyant.
That's fine if he is able to use your octo etc. and can hold on
to you, but what if he is unconcious and its a CBL?
Without the cylinder in the way go behind and wrap your legs round him and hang on with one hand under arm/across chest.
You can use the other hand to inflate etc.
So no need to complicate things, either give him your alternate,
grab hold and take him up, then dump w/belt on surface. Easy.
Or grab, get in position, lift and dump weight on surface.
TerryH
hmmm interesting...i must admit my first thought would be to leave the weightbelt in place and make dam sure i got a good hold of them so i didnt lose them on the way up...
A couple of exercises you could try yourself to get a better feel for the problem.
+CBL using a divers drysuit.
+Snorkelling in a wetsuit.
I am really surprised at Nigels 14Kg example. I use about 12lb snorkelling in a neoprene drysuit (3mm) and it was about 8lb when I had a membrane suit. Fully kitted in a single I use 20lb and 16lb respectively. The 8lb I wear in twin 12s is only needed if I happen to find myself shallower than 3m with less than 50bar. My twin 7x300s are sufficiently negative that creating positive buoyancy is more the problem.
i guess this is one scenario that would be helped by the people who carry ponies side slung like stages...they then could just hand off a pony and even if you become very positive and jet to the surface...at least i dont have to come with you...and you can breath all the way up ....hmmm even more ponder :)
Nope. During a rapid ascent the only way to breathe is out. Given the casualties predicament there is no way I would want to lose positive contact.
Personally, presented with an equipmentless diver at 20m I would not want to dick about too much. Just get them to the surface as quickly and ssafely as possible. Unless they look very overweighted I would leave the weightbelt in place. Up to about 6m a correctly weighted rescuer should have enough negative buoyancy to control the ascent. During the final 6m you can slow things down quite a bit just by using your fins to create drag.
Nigel Hewitt
26-08-2005, 12:32
I am really surprised at Nigels 14Kg example.
So was I. The first time I put the oxygen rebreather in the water I had to keep going back for more lead and afterwards dunked it to check it was really neutral (it was). 8 lumps mostly stamped 1.7+Kgs that were probably supposed to be 4lbs.
I think the quilted booties were the final straw but the 200gm undersuit holds a lot of gas. I confess, however, it's mostly me. I can do the DM float with hands out of the water without moving a muscle and that's in a fresh water pool (Yeah. I know. That Nigel. He's full of hot air.)
:=How about attaching a line on a reel to the weight belt and the kit and handing the reel to the diver before removing the gear. If the diver wasn't panicking, perhaps he could control the ascent by gradually letting out the line
I wondered about this one but my concern is that with several kilos of buoyancy to overcome we are talking about a diver 'hanging' upside down with the suit unable to dump and getting progressively more buoyant as we go up. I can't see a way to make the line feed from the fins end so to speak.
Turn him vertical before tieing him off, dump all gas then get him to reel himself up? No air in d/s to start means it couldnt expand. In reality of course ther would be some trapped which would expand but assuming he stayed fins down at the start he wouldnt expand much gas.
Matt
:=Ok here goes...
:=I often wonder about incidents and how i would react if it where to happen to me...for warned/planned is forarmed as they say.
:=So imagine you came across a trapped diver...say at 20M the only way to free this chap is to remove him from his kit...his kit remains trapped so you cant put the casualty back in his kit after.
:=Obviously you then have to lift the unkitted casualty on your gear..ok no problem so far...but what about his weight belt ?
:=
:=1.Do you ditch it at depth, with the possibility of him becoming very positive and taking u both to the surface ?
:=2.Do you bring him up with him still wearing his weight belt and then ditch at the surface, with the possibility of loosing contact with him on the way up and him sinking down again without air....
:=
:=hmmmmm what would you do ? :)
Easy awnser.
On a standard assisted ascent you are taught to share air and
lift using your BC. The scenario works on the premise that if
this guy is OOA chances are that there wont be any for his BC
as well.
Take away the cylinder and BC and ignoring any residual air
trapped in the BC, he will be lighter even with the w/belt.
So you can (as before) do a standard ascent. Soon as you reach
the surface you then dump the weightbelt a hes
bouyant.
That's fine if he is able to use your octo etc. and can hold on
to you, but what if he is unconcious and its a CBL?
Without the cylinder in the way go behind and wrap your legs round him and hang on with one hand under arm/across chest.
You can use the other hand to inflate etc.
So no need to complicate things, either give him your alternate,
grab hold and take him up, then dump w/belt on surface. Easy.
Or grab, get in position, lift and dump weight on surface.
TerryH
Terry surely with kit removed he's going to be massively underweighted and therefore drag you up with him in an uncontrolled manner? That's also ignoring the fact that many dive with no ditchable weights i.e. twins with V weights etc.
Matt
Nigel Hewitt
26-08-2005, 17:48
Terry surely with kit removed he's going to be massively underweighted and therefore drag you up with him in an uncontrolled manner? That's also ignoring the fact that many dive with no ditchable weights i.e. twins with V weights etc.
But they aren't the ones that get stuck in wrecks and need to be dekitted to pull them out. 8-)
You may need a cold chisel to prize their fingers off the binnacle before they run out of gas but they can normally get out of anything they can get into.
:=
Terry surely with kit removed he's going to be massively underweighted and therefore drag you up with him in an uncontrolled manner? That's also ignoring the fact that many dive with no ditchable weights i.e. twins with V weights etc.
Matt
Depends what you mean by "massively". Chances are that you have
enough air in BC/drysuit (depending how you dive) to be able
to dump/control on the ascent. Might be a litle more than usual,
bit fully controllable nonetheless.
T.
Nick Simmons
20-09-2005, 17:40
If you were to work to the rule 'don't become the casualty' then I would leave the weight belt on and get a seriously good grip on the casualty. Then you have got a fair chance of getting him/her to the surface in a controlled manner. I dive with a pony AAS so the casualty could breathe of that.
I'd crack a DSMB first before the ascent - preferably secured - then the casualty has got something buoyant to grip onto at the surface until rescue.
I think if you were to remove the weight belt the ascent would be uncontrolled due to the casualtys buoyancy, putting the rescuer at risk of a DCI and what use are you then???
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