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Lucky Man
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2,163 Posts
Discussion Starter #1
Bought my first lift bag a while ago, not dived with it or used it yet.

It is yellow balloon shaped 50lb one, self sealer with dump valve.

Just tried inflating it at home (after having some fun with self sealer DSMBs failing to seal) and it doesn't hold it's fill at all, air just gushes back out down through the inlet at the bottom.

Noticed that the dump valve has pull string fastned to the inside of it, and string comes out down through the inlet. I don't see how it is ever meant to seal properly like that.

Is this a naff design, a falty bag, or some misunderstanding on my part?

Cheers,
Dave
 

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R.I.P.
Joined
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5,709 Posts
what make and model of bag have you got?

There are few different designs available. Some have an open ended bottom (which i suspect you have) and some have a 'sealed' end like an SMB that prevent air from escaping.

Whatever design you have, stick a length of rope on the end and attach your 'goodies' to that. As the bag hits the surface, the weight of the 'goodies' suspended on the rope should help prevent the bag toppling over and spilling the air. I also use an old postal sack attached to the rope for chucking in smaller bits and bobs.....

I need a new lifting bag as well. I found a porthole last week and the lifting bag split when it was on it's way up!

have a look here.... Lifting bag help. . . - South West Mafia
 

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Mad as a Haddock
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2,206 Posts
Usually, the hole at the bottom is at the bottom (?) so the air stays in, any expansion as it rockets skywards just blows out, inverted bucket principal. As long as it doesn't leak from anywhere else, should be ok.
 

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www.finingaround.co.uk
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1,826 Posts
I depends on the bag you get 3 types I can think of
1. open end - relies on weight of object to keep upright and hence air in it
2. semi closed like a SMB where there's baffels in the bottom with the air pressure stops it coming out
3. closed circuit which has a one way valve and an over pressure valve whic stops it exploding

Fin
 

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Lucky Man
Joined
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2,163 Posts
Discussion Starter #7
it's exactly like this one:
Great deal on SEA ELITE 50LB LIFT BAG LB YEL from Divers-Supply.com

Looking at it a bit closer I reckon it is actually an open ended one, as although the inlet narrows, it doesn't feel smooth insiude at the narrowest point like and self sealing SMB does. And it has rthe string going up it, which I think is as per design looking at the web, not dump acidentally inside out.

I'm going to have a go at using instead of a DSMB on Sunday and see if weight on it does keep it full.

Cheers all,

Dave
 

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Utrinque Paratus
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6,077 Posts
the bag is fine the reason the valve is inside is so that as you surface you can dump air to keep it the same buoyancy as you, if your just sending it up unsupported as the pressure increases the air will come out from the base.

if it was the other way round and you tried to lift something heavy the valve would give way first releasing the air and lifting F.A.

its not meant to seal as the weight of the object keeps the bottom under water the moment you lift it out the bag deflates and is easy to handle

the Halcyon ones are sealed and are a royal pain in the ar5e when lifting large objects

Hope this helps

Graham
 

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Lucky Man
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2,163 Posts
Discussion Starter #9
Excellent cheers Graham and all.

Now I just have to find something worth lifting at the weekend :)

Steve, don't worry mate I'm not after your Oceana porthole, despite how this thread might look (testing out his new lift bag after previous porthole stealing threats :bat: :D)

Dave
 

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Utrinque Paratus
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6,077 Posts
But if you would like to sell it to me :D

Graham
 

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R.I.P.
Joined
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5,709 Posts
Excellent cheers Graham and all.

Now I just have to find something worth lifting at the weekend :)

Steve, don't worry mate I'm not after your Oceana porthole, despite how this thread might look (testing out his new lift bag after previous porthole stealing threats :bat: :D)

Dave
Hey Dave,

ha ha It's not my porthole....If you find it then good luck to you. It would be nice if someone off these boards brought it up. There are plenty more out there to found and i'm not diving the Oceana for a long time yet....

regards

Steve
 
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