stern gun
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lermontov
Contributor
Donated to a military museum.
dlofting
Contributor
Not in international waters beyond the 12 mile limit.
How deep is the wreck roughly? Once a lift bag starts it's thing, it's a straight shot to the surface and we had a steel billet at 185' come back down on top of us. When the waves snapped the nylon at the surface.
67m. You need to control the lift with decent dump valves and a mooring on the wreck. You can see from the video the top of the bag is just on the surface. The bag can be left go once your shallow enough that it can take the expansion without dumping when it hits the surface, if it over expands and speeds up it will fall over on the surface, dump and head back down.You need a bag with at least twice the lift capacity of what you're lifting. Either way it's a dodgy exercise even when everything goes right. If the bag gets away better not get caught in it or be under it on the way back down. Winch and cable is a better idea deep. Leaving a bag off from the bottom and hoping for the best is a good way to lose the bag and what's on it.
Still Kicking
Contributor
If you have to lift bag something like that, the right way is with a couple of long ropes and two (or more) bags. Lift from 30 feet to the surface and then repeat, so it's much easier to control. Plus it's safer because you're spending most of your working time shallow and if things go sideways you are not below it.
That will only work for something that can't foul. If it fouls how will you release it and be able to see what you're doing to keep it under control. A blind lift is not a good idea. In the video you will see there's wreck structure above the gun so we first had to bring it clear of the wreck by taking the weight with a bag and moving it under control. It's not hard to control even a large bag once its designed for the job, once you tie it off and just get it bouncing you can maneuver it around on the bottom.
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