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Discussion Starter · #1 ·
Hi All,
I am running a Dive Leader training weekend at Stoney. DO4 (Shot recovery etc), is excercised with a 10-15kg shot with a safety weight 4-5 kgs on a 1 meter line.

Which lifting bags would you recommend? There are several on the market, some with dump valves to control ascent, some with simple Over pressure valves, some are self sealing and some simply open ended.

I would appreciate any recommendations based on experiences with trainees using them. I am a Inspiration Trimix diver - so a self sealing one that can double as a deco buoy is appealing :)

Thoughts appreciated.

Kind regards, Andy
 

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We use multiple standard buddy DSMB blobs. You can add more
depending on the weight of the shot and can be fine tuned for
control.

We've got a couple of large lifting bags for S&R practice, but
find DSMB's work better for this module.
 

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Team Peanut Butter
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I use two types of lifting bag a 45 Kg open ended bag and a 35 kg self sealing one with an over presure valve. the 35 kg bag is easier to control but I like the students to experiance both types of bag as this may help them decide what type they may want to spend thier money on.

Graham.
 

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Discussion Starter · #4 ·
HI Graham, I haven't seen you for over a year! hope you are well!

Good idea on the above, what makes do you have? Is the 35 kg a beaver?
Andy
 

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ummm i actually use two buckets :)

easy to demonstrate and to be visual with :-s plus much easier to control then a lift bag.....
 

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I use a 25kg buddy one, its useful having the dump at the top of the bag for control which you don't get on a buddy DSMB.

I enjoy teaching that one as its something a little different.
 

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Discussion Starter · #11 ·
Great guy's thanks for the pointers :)

I have a breakdown of the skill to be taught: Attach bag, inflate a little, deflate etc etc etc
Anyway - when we get to the actual lift, I was taught to release the bag and allow it to ascend freely to the surface, making sure divers move away from the launch point should the bag deflate on the surface and plumet back down.

Is this correct or are we now taught to control the bags ascent? "As I was taught to do on my recovery and lifting course a few decades ago". I'm asking because the posts above have put some doubt in my mind:
having the dump at the top of the bag for control Etc :)
 

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Conscientious Objector
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When we did it, we were taught two skills. The first was to send up a shot (or similar) on a lift bag (ie top it up and run for cover). The second was the S&R skills one, where you use the bag to make the item neutrally buoyant, then bring to the surface with you.

The former is no more difficult than sending up a blob. The latter is hard work.
 

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ite pretty simple...

One big bucket, with handle, and one small bucket with handle.

They act as lift bags, BUT as they are not "bag" shaped, there is more air at the bottom then at the top, thus, you can demonstrate VERY easilly, the spilling out of air when the air expands within the bucket.

Further as well, it makes it very very easy to dump air out of, as you just "tilt" the buckets a little bit, and the air comes pouring out. Thus, if the bag (buckets) get out of control, the odds are that they will turn a bit, and loose some air, and thus will come back under control.

I settled for buckets after teaching lift and shift about 30 times in one season, and got sick of using the Bags, which ended up with holes and often did not dump quick enough, and also proved difficult to control some times. Whereas a bucket,,, well, its difficult to hole a bucket, and its just much more visable and easier to control. A 10L bucket, lifts 10kg's of lead... simple. But by having two buckets, one small one large, you end up with a control bag.

Trust me on this, in a weird way, it just works..... try it :)
 

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I use a 25kg buddy one, its useful having the dump at the top of the bag for control which you don't get on a buddy DSMB.

I enjoy teaching that one as its something a little different.
Ah, but in this module you dont need it.

This is about learning how much gas to put in the bag so you
can at first make it neutral to move it (where it is now might
not be the best place to send it up, overheads etc) and then
just that bit more to initiate the ascent letting expansion do
the rest.

A dump will still work on the ascent wherever it's placed so
the only need for a dump in this case is so that you can
release the gas for practice.

I do away with the safety weight and use a strop attatched
to a bit of wreckage as per tethered deploy, so we've even
got continunity. Only reason for the safety weight is that you
cant guarantee a handy bit of metal around so BSAC had to
assume there wasnt one at this location.

Reason the blob works well is that it is easier to see how
much gas you are putting in and do some basic calcs as to
lift. You can also use it as a training tool (assuming the usual
more than one needed) by letting each student add a blob
of there own. The fun bit is that non of them know how many
will be needed for this shot so are always worried that it will
start the lift, making them very methodical, which is after all
what we want.

DSMB isnt just a cop-out because we have them, it's got a lot
of things going for it as a teaching aid.

Besides one thing missed in all this is that we carry DSMB's
some of us multiple ones, so it would be a bit daft not to
recognise we have a lifting aid. I was lifting an anchor last
year and handed my lifting bag to a mate. Not sure what
happened, but last he saw, it was on the way to the surface.
A few multiple blobs later and the same result acheived :teeth:
(we picked up the lifting bag, still rolled up later)
 

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All hail the mighty ZOM
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35kg lifting bag, safety weight, 2m rope with a caribener on each end, 2m webbing with a boltsnap on each end. All fits into my drysuit pockets. Jump in, find my "secret breze block" the spend ages lifting it up and down.

Secret breze block last seen just off the steps on the quay.
 

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35kg lifting bag, safety weight, 2m rope with a caribener on each end, 2m webbing with a boltsnap on each end. All fits into my drysuit pockets. Jump in, find my "secret breze block" the spend ages lifting it up and down.

Secret breze block last seen just off the steps on the quay.
Maybe I've read this wrong, but this is recovery of shot and unless the
block has a rope and blob on the surface and gets sent to the surface,
it seems all you are doing is moving it around or a S&R exercise.
Avoiding that loop of rope is as important as not being underneath.
Like I say though could have read this wrong.
 

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Ah, but in this module you dont need it.

This is about learning how much gas to put in the bag so you
can at first make it neutral to move it (where it is now might
not be the best place to send it up, overheads etc) and then
just that bit more to initiate the ascent letting expansion do
the rest.

A dump will still work on the ascent wherever it's placed so
the only need for a dump in this case is so that you can
release the gas for practice.

I do away with the safety weight and use a strop attatched
to a bit of wreckage as per tethered deploy, so we've even
got continunity. Only reason for the safety weight is that you
cant guarantee a handy bit of metal around so BSAC had to
assume there wasnt one at this location.

Reason the blob works well is that it is easier to see how
much gas you are putting in and do some basic calcs as to
lift. You can also use it as a training tool (assuming the usual
more than one needed) by letting each student add a blob
of there own. The fun bit is that non of them know how many
will be needed for this shot so are always worried that it will
start the lift, making them very methodical, which is after all
what we want.

DSMB isnt just a cop-out because we have them, it's got a lot
of things going for it as a teaching aid.

Besides one thing missed in all this is that we carry DSMB's
some of us multiple ones, so it would be a bit daft not to
recognise we have a lifting aid. I was lifting an anchor last
year and handed my lifting bag to a mate. Not sure what
happened, but last he saw, it was on the way to the surface.
A few multiple blobs later and the same result acheived :teeth:
(we picked up the lifting bag, still rolled up later)
Wow, comprehensive answer there Terry!

Yeh, what your saying makes sense but I guess I approach it differently. I like to have a student reposition the shot and let the air out of the bag and then send it up afterwards. It relects what you do in practice, possibly being asked to move a shot to make sure its in properly or move it so its easy for the skipper to hoik it out after the divers are up. I'm not sure how you can do that with a DSMB with the dump valve on the bottom. But as always there are different ways of teaching the skill, as long as the diver manages to get the experience to do it in 'anger' thats all that matters.

Cheers,

G
 

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I'm not sure how you can do that with a DSMB with the dump valve on the bottom.
Multiple DSMB's :teeth:

Depending on the weight of the shot, the first one will be full, so the dump is
alongside you. Pull that and enough gas comes out to make neutral into
negative. You can now pull it down and do the same for the other(s)
alongside.

Other way is attach a thicker cord to the hole in the top, so you can
pull it over and let ambient pressure do the rest.

Finally if you have to you can rise up 1m and just pull it over as
above. Once horizontal it doesnt matter where the dump is.

Jeeze it's almost like we've thought through this s*it :teeth:
 
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