Lift bags..

[ScoobieDooo]

Can someone give me a 'crash course' on lift bags?

I have never used one, other than the 'obvious' of using them t LIFT artifacts and objects up to the surface, what value do they hold for rescue, emergencies, etc.

AND...

What should I be looking for in purchasing a lift bag, as far as size, amount of lift, etc.

 

[Doppler]

ScoobieDooo once bubbled...
Can someone give me a 'crash course' on lift bags?

I have never used one, other than the 'obvious' of using them t LIFT artifacts and objects up to the surface, what value do they hold for rescue, emergencies, etc.

AND...

What should I be looking for in purchasing a lift bag, as far as size, amount of lift, etc.

In Five Sentances or Less!!!

Value for emergencies relates to having something to send to the surface to 1/ float a temporary ascent line -- you couldn't find the permanent one! 2/ surface marker either for signalling to the topside crew that you need something -- slate attached to the bag with a message on it -- like send down warm underwear and a sandwich ut: -- or to show them where you are when doing a drifting deco or safety stop... as in live boating.

Size is going to depend on surface current somewhat, but if you want a good general purpose as a float and emergency marker, 50 pounds is useful.

Self-sealed bags are easier to operate and stay inflated on the surface better than open bags.

More than five sentances... sorry

DD

 

[ScoobieDooo]

Doppler,
What do you mean by 'self sealed?'

 

[rmediver2002]

Closed bottom bags are similar in function to a BC bladder, they have an inflation port and a self venting exhaust valve.

Open bottom bags are more like an inverted bucket. If they ascend to fast and "leap" from the water upon reaching the surface they will tend to lay down and allow the air to escape out the bottom. (they can collapse and lose all buoyancy)

(not at all desirable when lifting heavy loads...)

When using a bag for loads the bag should be a capacity just slightly over the working weight of the load being lifted.

http://www.e-nekton.com/liftbags.html

Jeff Lane

 

[Doppler]

Good post Jeff:

There you go Scoobie. Jeff has answered your question and sorry I did not explain myself very fully.

Good luck... and practice deploying the bag before you need to use it in earnest!!!

DD

 

[cadet diver]

I would just get a surface marker with an equivilant amount of lift. Like a 50# or a 90# marker. That way if you ever get into deco diving you already have one. They are good safety devices to have on the surface, and can still lift stuff.

 

[DIR Tec Diver]

They can also be used to address a buoyancy failure. The closed circuit design can allow you to purge the air from the bag just like a dump valve on a bcd. Despite what some people may think you can still orally inflate a closed circuit lift bag or SMB, which is a nice piece of info in a compromising situation. Of course your buddy can provide the needed air as well. Closed circuit is definitely the way to go, but take some extra considerations, but are however well worth it

 

[Doppler]

DIR Tec Diver once bubbled...
They can also be used to address a buoyancy failure. The closed circuit design can allow you to purge the air from the bag just like a dump valve on a bcd. Despite what some people may think you can still orally inflate a closed circuit lift bag or SMB, which is a nice piece of info in a compromising situation. Of course your buddy can provide the needed air as well. Closed circuit is definitely the way to go, but take some extra considerations, but are however well worth it

Would you mind explaining how you would address a buoyancy failure using a lift bag.

Thank you

 

[Pez de Diablo]

The last thing in the world I want to do is agree with Mr. DIR.

But yes, if your BCD fails and your drysuit fails or doesn't provide enough lift, you can deploy a lift bag to maintain buoyancy. Give it a little gas and you are neutral, with a little kick up, you start your ascent, then you dump as you go up to maintain a slow steady ascent and maintain any deco obligations.

OR, the easier way

Shoot the bag to the surface and reel/spool yourself up.