OP
what do you guys use lift bags for?
- Thread starter sterlingMarineService
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Jorgy
Contributor
It all honesty is not true lift bag and other than a small anchor and a dropped weight belt that is all I have ever lifted with it......
It was a something like a 30 lbs belt and my travel wing is on 18 lbs I did not feel like trying to swim it to the surface.......a really big guy dropped it in forty feet of water in Aruba while trying to get back on the boat........
I was still hanging under the boat at 15 feet and saw it go by.......
The DM was surprised to see it pop to the surface beside the boat.......
He was gearing up to go retrieve it......
M
It was a something like a 30 lbs belt and my travel wing is on 18 lbs I did not feel like trying to swim it to the surface.......a really big guy dropped it in forty feet of water in Aruba while trying to get back on the boat........
I was still hanging under the boat at 15 feet and saw it go by.......
The DM was surprised to see it pop to the surface beside the boat.......
He was gearing up to go retrieve it......
M
Jorgy
Contributor
For non-commercial work I think the Carter is awesome......
It is super versatile, easy to store and deploy and well made......not to mention affordable.....
Goes with me on every dive........
M
It is super versatile, easy to store and deploy and well made......not to mention affordable.....
Goes with me on every dive........
M
OP
sterlingMarineService
Contributor
Jorgy
Contributor
I carry a small finger spool with 40 feet of line on it.......
I have the 5 and 10 foot increment marked in black on it.........
The 15 foot increment is marked with black/red/black.......
It is one of those $10 jobs with most of the line removed....
When I use it a dive flag I have a Manta Jr reel......
M
I have the 5 and 10 foot increment marked in black on it.........
The 15 foot increment is marked with black/red/black.......
It is one of those $10 jobs with most of the line removed....
When I use it a dive flag I have a Manta Jr reel......
M
Attachments
We use an DSMB for a stable depth for free-floating deco. One blob should be good enough for a whole team. We don't "hang" on them as much as use them for a visual reference for exact depth. One diver of the team sets his/her depth exactly with the deco-buoy and the other divers use that diver as a visual reference for stop depth.... at least how we do it. A deco buoy is also essential when there are zodiacs around so you don't get run over!
As for lift bags:
When we're wreck diving we usually use grappling hooks/anchors to tie off the upline on the wreck. At the end of the dive, the last diver up uses a lift-bag to return the grapple to the surface.
On wreck dives we also stage a "basket" or a net by the grapple for divers to deposit their finds in so they don't have to try managing their ascent with stuff in their hands. This basket is brought up with a lifting bag too.
Some individual divers also use them for lifting their "own" finds if it's something they don't want to carry back to the upline. For example, it might be too large or awkard to swim the distance of the wreck back to the upline. Obviously this only works if we have a Zodiac as a tender.
R..
Well.... it could lift the Titanic if the Titanic were only 100lbs negative under water. You can make a whole study of how much negative buoyancy an object has under water.....
Google: Archimedes Principle
An interesting problem that can be solved with archimedes principle is, for example, a question like "how big of a lift bag would you need to raise a 1500kg anchor assuming that the anchor was totally made of steel".
A: You know steel has a density of 7.7kg per liter. 1 litre of air creates a kg of positive buoyancy under water. So your 1500kg steel anchor actually "weighs" about 1305kg under water. so you'd need a lift bag of 1305 litres to lift a 1500kg steel anchor.
Similar questions can be posed for all kinds of objects if you know how much they weigh, how much volume the displace... and if compression has an affect on their volume under water, what depth they're at.
A corollary to the question above about the anchor would be this: Assuming you only had 500kg lift bags and the Anchor was 8 metres long, how would you attach the bags to the anchor and how many tanks of air from an AL-80 would be needed for a lift from 20 metres? Also, planning the dive above, how many divers would be needed to raise the anchor from 8 metres of water? What about from 28 metres? or 80 metres? How would the depth affect your dive plan?
So the answer to the question you posed depends on a lot of variables. But the exercise itself is a very interesting puzzle.
R..
(D)SMB aka sausages are for signaling your presence. They have little lift, but used correctly can be seen from afar on calm waters.
Lift bags are usually small and wide (balloon or ball shaped) and are used to lift things off the bottom. They are not good signaling devices as they usually do not stand up from the surface.
Lift bags are usually small and wide (balloon or ball shaped) and are used to lift things off the bottom. They are not good signaling devices as they usually do not stand up from the surface.
kanonfodr
Contributor
I use an OMS 6'2" SMB as a lift bag. Mostly it's used for practice, but it's really there for if I have a wing failure. It has 30# of lift, so if I find something not tooo heavy underwater that I want to retrieve, I could.
The question is: what primary use do you need a lift bag for? If you envision salvaging items, then you will not only want a heavy duty lift bag, but some pretty tough line to tie it off with. Possibly even chains, depending on the lift. I'm no expert, however. But if you're like some other divers and just ensuring redundancy in case of failure, then you won't need that much lift. Much less if it's just a deco line, a very small SMB would do very well for you.
Mine manages to fill all three in their ultimate precedence: surface location, deco assistance, redundant lift, and finally salvage.
Peace,
Greg
The question is: what primary use do you need a lift bag for? If you envision salvaging items, then you will not only want a heavy duty lift bag, but some pretty tough line to tie it off with. Possibly even chains, depending on the lift. I'm no expert, however. But if you're like some other divers and just ensuring redundancy in case of failure, then you won't need that much lift. Much less if it's just a deco line, a very small SMB would do very well for you.
Mine manages to fill all three in their ultimate precedence: surface location, deco assistance, redundant lift, and finally salvage.
Peace,
Greg
OP
sterlingMarineService
Contributor
Well i have an smb, but want a bag for salvaging small things as when I salvage a boat I need a different kind of lift bag that Is quite large and needs an air compressor so right now all I want is like a 50-100 pound for small items to be salvaged....
But also what kinda line would hold up?!
But also what kinda line would hold up?!
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