Incident Involving Drop Bottle and Deep Diving

Capt Morgan said:
The drop set had gas ranging from about 60m to 6m this would be attached
to the end of the line and the SMB deflated and the drop set deployed.
This would leave the SMB available to the diver to use again if needed.
Click to expand...

I've always just attached and lowered the drop bottle down the line but I like that idea. it's worth stealing. thanks.
 
Capt Morgan said:
The drop set had gas ranging from about 60m to 6m this would be attached
to the end of the line and the SMB deflated and the drop set deployed.
This would leave the SMB available to the diver to use again if needed.
Clear instructions were given to all the divers so everyone knew the protocol.
Click to expand...

Nice idea. Max depth for these dives? How much gas did each diver carry on the bottom? How far "up" did they plan to have to go to intercept the 60m dropped bottle?
 
lizardland said:
If you want the crew to help, make it as simple as possible for them. Put the regs on. Analyse the gas. Rig the bottle. Discuss what the plan is for using it so everyone is clear. Or just leave it to someone else then whinge when it turns into a **** up... But I'm a paying customer and someone else should look after me...

It goes wrong so blame the crew. They didnt forget to put a reg on, the divers did. They didnt forget to analyse it, the divers did. They didnt rig it badly, the divers did.
Click to expand...

I would have to agree that you are responsible for your own butt. If you are relying on a drop bottle, not only analyze it, put a reg on it and test it... place it yourself and if you are not placing it, visually see it in place on your way down ESPECIALLY for such a deep dive and that fact that the bottle never got placed on the first dive, nor had a reg on the second dive. It's a bit of a surprise that any of this story is true. What was the name of the group? Suicide Divers?
 
Capt Morgan said:
I've had the opportunity of having a few trips with what I would call
big hitters in the Irish diving community, I'd go so far as to say in the
diving community as a whole.
Before the trips the drop sets are arranged between the divers, so you know
what you have to take.
On the first day of diving all the sets are analysed, labelled and rigged.
The last trip had a total of four drop sets, thankfully none were used.
No gas was staged as the belief is that if you have an emergency you
should go directly up, get shallower where your gas will last longer and
then send up a bag. No point wasting gas going back to the shot when
it could be a long way off.
The drop set had gas ranging from about 60m to 6m this would be attached
to the end of the line and the SMB deflated and the drop set deployed.
This would leave the SMB available to the diver to use again if needed.
Clear instructions were given to all the divers so everyone knew the protocol.
Click to expand...

After diving with the Irish lads, I also stole the idea of a Donegal Drop Set for some of our deeper dives. Deep, intermediate, and shallow deco gas secured with locking SS carabiners braided into the line at set depths under a large poly ball. Nice to be able to deploy a set for an individual/team that may be either blown off the wreck or ascending for drifting deco away from the remainder of the team due to an issue. This allows the boat to tend to both groups, and potentially drop a safety diver to check on things. Surprised more folks don't implement this system.

And the originally posted scenario is on the divers for failing to insure an adequate system was in place. Especially allowing it to happen on multiple dives...once was bad enough, but then not recognizing it and addressing it after that?!
 
rjack said:
Nice idea. Max depth for these dives? How much gas did each diver carry on the bottom? How far "up" did they plan to have to go to intercept the 60m dropped bottle?
Click to expand...

On the last trip the depth was up to 90m. The cylinders were fixed at there MOD on the drop line so you could
basically switch to the tank at your given depth.

barney said:
After diving with the Irish lads, I also stole the idea of a Donegal Drop Set for some of our deeper dives. Deep, intermediate, and shallow deco gas secured with locking SS carabiners braided into the line at set depths under a large poly ball. Nice to be able to deploy a set for an individual/team that may be either blown off the wreck or ascending for drifting deco away from the remainder of the team due to an issue. This allows the boat to tend to both groups, and potentially drop a safety diver to check on things. Surprised more folks don't implement this system.

And the originally posted scenario is on the divers for failing to insure an adequate system was in place. Especially allowing it to happen on multiple dives...once was bad enough, but then not recognizing it and addressing it after that?!
Click to expand...

It's a great system Michael that's for sure.
 
Surley deep drop tanks only work in zero current?

Most of the diveing I do the string of drop bottles would be draged out away from the shot probably beyound the viz range of the diver in trouble.

Howard had a hell of a job seeing his drop bottle on the Mallin trip


For me thers only two ways a drop tank works.

1: Drop it down the station line

2 Gaf the Yellow SMB lift it up and clip the drop tank to the SMB line so it drops prety much on the hand of the diver needing it.


If we want spare deep bailouts they are staged on the shot line. We dont because we carry all but the 80% and I havent done a dive where three 10ltr / AL80s wasn't enough to get to the 9m stop

If I did id have staged gas

ATB

Mark
 
Capt Morgan said:
I've had the opportunity of having a few trips with what I would call
big hitters in the Irish diving community, I'd go so far as to say in the
diving community as a whole.
Before the trips the drop sets are arranged between the divers, so you know
what you have to take.
On the first day of diving all the sets are analysed, labelled and rigged.
The last trip had a total of four drop sets, thankfully none were used.
No gas was staged as the belief is that if you have an emergency you
should go directly up, get shallower where your gas will last longer and
then send up a bag. No point wasting gas going back to the shot when
it could be a long way off.
The drop set had gas ranging from about 60m to 6m this would be attached
to the end of the line and the SMB deflated and the drop set deployed.
This would leave the SMB available to the diver to use again if needed.
Clear instructions were given to all the divers so everyone knew the protocol.
Click to expand...



Am I to understand the diver with the SMB up has his tanks (negative) attached to his SMB then the SMB is deflated so he ends up with a string of overweight tanks he has to reel into him self whilst holding a neutrol stop???

I must not be understanding this properly

We lift the SMB and clip a large suicide clip to the SMB line then drop the tank

The suicide clip slides down the SMB line and the diver has the tank land on him and still has his SMB up for suport.

I have dne this in anger and you can feel the SMB being lifted and the tank as it drops down the line so You know its hapening and can prepair your self. The main issue being md water currents that drag the tank off to one side and the neg weight of a 10ltr full of nitrox landing on you.

Note Al80s dont make good drop tanks as they are too floaty empty. If we have to use them we strap lead to them. Light tanks are more easily snagged up by the current so a heavy nitrox filled steel 10 slides down better.


PS: we didnt just do a system on paper and dive it. We parcticed it in a puddle and practiced it on a dive boat under real world conditions.

First time we droped an AL80 with 200 bar in it, it stoped half way down the line (to 21m) and held there in the current even though we were drifting under a SMB?? If you had a gas leek and were down to 150 bar it wouldn't sink at all




ATB
 
Mark Chase said:
Am I to understand the diver with the SMB up has his tanks (negative) attached to his SMB then the SMB is deflated so he ends up with a string of overweight tanks he has to reel into him self whilst holding a neutrol stop???

I must not be understanding this properly

We lift the SMB and clip a large suicide clip to the SMB line then drop the tank

The suicide clip slides down the SMB line and the diver has the tank land on him and still has his SMB up for suport.

I have dne this in anger and you can feel the SMB being lifted and the tank as it drops down the line so You know its hapening and can prepair your self. The main issue being md water currents that drag the tank off to one side and the neg weight of a 10ltr full of nitrox landing on you.

Note Al80s dont make good drop tanks as they are too floaty empty. If we have to use them we strap lead to them. Light tanks are more easily snagged up by the current so a heavy nitrox filled steel 10 slides down better.


PS: we didnt just do a system on paper and dive it. We parcticed it in a puddle and practiced it on a dive boat under real world conditions.

First time we droped an AL80 with 200 bar in it, it stoped half way down the line (to 21m) and held there in the current even though we were drifting under a SMB?? If you had a gas leek and were down to 150 bar it wouldn't sink at all




ATB
Click to expand...

Hi Mark
Did you not find when sliding the bottle down the smb line that if a current is running than the SMB line will be at a considerable angle so hence the bottle will stop midways down the line. Now if the bottle was clipped directly to the deflated SMB this does not happen as the diver just reels the bottle attached to the SMB back to himself regardless.

Cathal
 
I've seen drop bottles with spare DSMBs attached (deflated) ready to be sent down the line, which is a neat way of doing things if you must have another bag to replace the one you sent up.

After a recent day of fiascos trying to recover anchors and have the SMBs and lift bags sent down the shot for the next recovery only to find that with a stiff breeze the boat was pulling me up on the line as it shot off downwind and the deck crew couldn't get the SMB empty enough to sink, even with a weight attached: I now know better. I would /never/ rely on a deck crew to get a SMB back to me in the water. Once it goes up it stays up.

Send me down a clipped tank on my yellow bag - but make sure it's my drop tank that I've analysed, marked and prepared for you to send me.
 
As a side note (and potentially setting myself up for ridicule) do you make certain that everyone agrees on max pO2? I do not label any of my cylinders with MOD. They are only identified with their contents. While many people mark MOD based on a pO2 of 1.6, others might be more comfortable with 1.4 while others yet would push to 1.8 or even 2.0. MOD involves a judgement about pO2. Marking contents does not. And the arithmetic should be very simple for each person to determine his own MOD for a gas, rather than marking a potentially shared bottle.


iPhone. iTypo. iApologize.
 
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cathal said:
Hi Mark
Did you not find when sliding the bottle down the smb line that if a current is running than the SMB line will be at a considerable angle so hence the bottle will stop midways down the line. Now if the bottle was clipped directly to the deflated SMB this does not happen as the diver just reels the bottle attached to the SMB back to himself regardless.

Cathal
Click to expand...


Only with Ali 80s

No problem with 250bar nitrox fills in steel 10s They were neg enough to slide as long as there was some angle in the line

If a strong current is to be expected then clip some lead to the tank neck ring


Our drop tanks are on a sofnalime barrel and have 6mm rope at MOD depth + 1m for the 9m tanks and +4m god forbid we used a 21m tank as we found depth length just didnt work. Deeper the tank more extra rope you need

At the bottom of the line is a clip that clips on to the tank neck ring & into a large loop in the roap

If you put an extra 4kg lead on the tank to sink it in a current you can unclip the lead and clip it to the deco tank line and clip the tank to your self so you dont have to manage the extra 4KG

Or if its all a bit stressfull, just ditch it its only lead.


I would have grave concerns about deflating a divers SMB in a stress situation.

Adding to that sending him down a negative tank of gas?

Doesent sound good to me

And my SMBs are crack bottle & C02 so a sod to reinflate if you delfate it for me

ATB

Mark
 
kwinter said:
As a side note (and potentially setting myself up for ridicule) do you make certain that everyone agrees on max pO2? I do not label any of my cylinders with MOD. They are only identified with their contents. While many people mark MOD based on a pO2 of 1.6, others might be more comfortable with 1.4 while others yet would push to 1.8 or even 2.0. MOD involves a judgement about pO2. Marking contents does not. And the arithmetic should be very simple for each person to determine his own MOD for a gas, rather than marking a potentially shared bottle.


iPhone. iTypo. iApologize.
Click to expand...



MOD is PP02 1.6 and should be for ALL gas IMHO but,

MOD for bottom mix might be 1.4 but thats not relevent realy as bottom mix is bottom mix. All other gas is deco gas so it should be 1.6

If the person wants to get on it a bit deeper or a bit shalower, that up to them but the MOD must remain a standard or we wont have a clue whare we are.

My drop tanks say 80% MOD 10m so you can make your own mind up and thers no uncertanty

003.jpg




NOTE Sofnalime barrel cliped to rear tank D ring not neck D ring. This keps the line away from the shot line as the tank decends

This is an old pic I now have a 75mm neck ring on the end of the drop tank line rather than just a loop

DropTank.gif





ATB

Mark
 
Mark Chase said:
Am I to understand the diver with the SMB up has his tanks (negative) attached to his SMB then the SMB is deflated so he ends up with a string of overweight tanks he has to reel into him self whilst holding a neutrol stop???

I must not be understanding this properly

We lift the SMB and clip a large suicide clip to the SMB line then drop the tank

The suicide clip slides down the SMB line and the diver has the tank land on him and still has his SMB up for suport.

I have dne this in anger and you can feel the SMB being lifted and the tank as it drops down the line so You know its hapening and can prepair your self. The main issue being md water currents that drag the tank off to one side and the neg weight of a 10ltr full of nitrox landing on you.

Note Al80s dont make good drop tanks as they are too floaty empty. If we have to use them we strap lead to them. Light tanks are more easily snagged up by the current so a heavy nitrox filled steel 10 slides down better.


PS: we didnt just do a system on paper and dive it. We parcticed it in a puddle and practiced it on a dive boat under real world conditions.

First time we droped an AL80 with 200 bar in it, it stoped half way down the line (to 21m) and held there in the current even though we were drifting under a SMB?? If you had a gas leek and were down to 150 bar it wouldn't sink at all




ATB
Click to expand...

Our drop set has a mushroom anchor (I think ~4.5 kg) on the bottom so the whole thing gets pitched over with a poly ball at the surface. Depth of the whole system depends on what the target is. Generally, a 60 m line is sufficient for most 80-100 m dives. We can secure another 30 m section and deeper mix for deeper dives. Divers are told if you are above 60 m when you shoot an emergency marker to make sure and look up as the whole system comes down on you fast. No need to slide a bottle down a SMB line. The SS locking carabiners prevent bottles from coming off inadvertently and lost.
 
kwinter said:
As a side note (and potentially setting myself up for ridicule) do you make certain that everyone agrees on max pO2? I do not label any of my cylinders with MOD. They are only identified with their contents. While many people mark MOD based on a pO2 of 1.6, others might be more comfortable with 1.4 while others yet would push to 1.8 or even 2.0. MOD involves a judgement about pO2. Marking contents does not. And the arithmetic should be very simple for each person to determine his own MOD for a gas, rather than marking a potentially shared bottle.


iPhone. iTypo. iApologize.
Click to expand...

Tanks labeled by MOD. Contents labeled near the neck but initial recognition is based on MOD label.
 
Mike Ferguson said:
i'd have said most knew the song but some were humming along in places.

I was a bit baffled by the 50% staged at 40m+, it did make it easy to collect on the way home if you needed it but personally I'd have had air at the bottom of the shot and left the 50% at 18m.
Click to expand...

Simple system really - We each carried an Ali 80 air bailout through the dive. The first pair in took a 50% and left it at the bottom of the downlink. Everyone left a tag on the 50%. The last person up brought the 50% back with them if it wasn't needed. It There were also bottles staged under the deco station at 20m and 6m and a safety diver on the shot until the last diver left the bottom. Great in blue water but not what I'd do in UK waters.
 
3 man team first in , find the wreck set up shot , then hang your own cylinders where ever the fook you like ,

Arsing about I call the down the reef then up a unknown line , drop tanks are for real fook ups not part of the plan , it's back up for the back up.
 
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kwinter said:
As a side note (and potentially setting myself up for ridicule) do you make certain that everyone agrees on max pO2? I do not label any of my cylinders with MOD. They are only identified with their contents. While many people mark MOD based on a pO2 of 1.6, others might be more comfortable with 1.4 while others yet would push to 1.8 or even 2.0. MOD involves a judgement about pO2. Marking contents does not. And the arithmetic should be very simple for each person to determine his own MOD for a gas, rather than marking a potentially shared bottle.


iPhone. iTypo. iApologize.
Click to expand...

Depth is a lot easier to interpret when stressed or with a bunch of bottles on than a percentage O2. Also easier to get confirmation from a buddy.

Since these are dropped bottles of deco gas I assumed everyone used a max of 1.6 and once the ppO2 had declined to ~0.8 their would be another bottle. I don't know anyone decoing at higher than 1.6 here (ever). Who does that?
 
rjack said:
Depth is a lot easier to interpret when stressed or with a bunch of bottles on than a percentage O2. Also easier to get confirmation from a buddy.

Since these are dropped bottles of deco gas I assumed everyone used a max of 1.6 and once the ppO2 had declined to ~0.8 their would be another bottle. I don't know anyone decoing at higher than 1.6 here (ever). Who does that?
Click to expand...

If I see a big 21 written on the side of the cylinder then I am going to think that is for use at 21m so most likely 50%. I am not going to think it is air.

But raises the question. Never breathe something you haven't analysed yourself ? So if you might need to breathe of the drop tank that someone else has brought along and labelled, analyse it again yourself before you dive ?

Should this also apply before using your teams bailout if you need to hand off or share gas ? Or because you have discussed with team how cylinders should be labelled it is ok to believe the label in those circumstances ?


Sent from my iPad using Tapatalk
 
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