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Curious how this is recovered. So they send down another submersible that is able to attach a cable to debris that can be pulled up by a winch?

jtriangle 3y ago
Yes, it's done via ROV's with manipulator arms that attach salvage cables to them. Way less failure prone than trying to bring them up with the ROV's directly because the ROV's are normally tethered via a fairly light duty tether that's connected to a base station that raises/lowers the craft. That keeps things much more maneuverable because the ROV doesn't have to drag around thousands of feet of cable, and, it provides some damping from any movement of the host ship operating it. Additionally, the ROV can stay submerged, looking for other things to grab, while salvage cables are raised/lowered. Doubly important because those sorts of winches run at ~1000ft/hr, and the wreck is ~12.5k feet down, so over a full day for one recovery.
- luzer7 3y ago
  They have 12k feet of cables?
  - pixl97 3y ago
    No, they have cables over twice that long... https://www.whoi.edu/what-we-do/explore/ships/ships-atlantis/ships-atlantis-scientific-equipment/ships-atlantis-scientific-equipment-winches-wires/ https://www.whoi.edu/what-we-do/explore/ships/ships-atlantis...
  - LandR 3y ago
    Worked on a software system for deep sea cranes, where they wanted us to be able to support them having 4000-8000m cables on the crane.
lb1lf 3y ago
I have never hauled submersible wrecks from the seabed, but have recovered lots of other stuff from the same place. Depending on the weight and bulk of the component, you'd likely do one out of three (at this depth; in shallower waters, you have more options) a) Small-ish items are simply dropped in a basket attached to the ROV doing the recovery, then brought back to the surface with the ROV. b) Larger items may be handled by the ROV to a basket suspended from a winch, then hoisted to the surface. c) If the items are too large for the ROV to handle, it will be used to attach a sling to the item, which is then in turn attached to the hook of a crane/winch, before being hoisted to the surface.
- dbancajas 3y ago
  and why did they do this? who paid for this recovery?
  - lb1lf 3y ago
    In the cases I've been involved in, it has largely been oil companies or their subcontractors footing the bill, occasionally scientists or, uh, treasure hunters. (I work for a company making this exact type of recovery gear, so every now and then I have to do some field work)
  - csb6 3y ago
    The U.S. Coast Guard is investigating the cause of the incident, so they are collecting evidence.
- jayrot 3y ago
  The Navy also has the FADOSS, though it wasn't needed here I believe. It can lift insane amounts, at insane depths. https://en.wikipedia.org/wiki/Flyaway_Deep_Ocean_Salvage_System https://en.wikipedia.org/wiki/Flyaway_Deep_Ocean_Salvage_Sys...
  - lb1lf 3y ago
    -This was interesting, thanks! It appears they utilize a passive system to dampen the effect of vessel movement, whereas in many (most?) other cases compensation is done actively by the traction unit (the twin drums with the rope looped over them in the center of the photo) and the storage winch (bottom) being wired to an accelerometer installed on the vessel. I guess the navy uses the passive system as it will be good enough and does not require that you spend time figuring out the vessel geometry to input the data into the winch control system - which is just another source of problems when you're in a hurry. I like this, it seems they've made the kit as simple and robust as possible while still fulfilling its intended purpose.

jtriangle 3y ago

Yes, it's done via ROV's with manipulator arms that attach salvage cables to them. Way less failure prone than trying to bring them up with the ROV's directly because the ROV's are normally tethered via a fairly light duty tether that's connected to a base station that raises/lowers the craft. That keeps things much more maneuverable because the ROV doesn't have to drag around thousands of feet of cable, and, it provides some damping from any movement of the host ship operating it. Additionally, the ROV can stay submerged, looking for other things to grab, while salvage cables are raised/lowered. Doubly important because those sorts of winches run at ~1000ft/hr, and the wreck is ~12.5k feet down, so over a full day for one recovery.

luzer7 3y ago
They have 12k feet of cables?
- pixl97 3y ago
  No, they have cables over twice that long... https://www.whoi.edu/what-we-do/explore/ships/ships-atlantis/ships-atlantis-scientific-equipment/ships-atlantis-scientific-equipment-winches-wires/ https://www.whoi.edu/what-we-do/explore/ships/ships-atlantis...
- LandR 3y ago
  Worked on a software system for deep sea cranes, where they wanted us to be able to support them having 4000-8000m cables on the crane.

lb1lf 3y ago

I have never hauled submersible wrecks from the seabed, but have recovered lots of other stuff from the same place. Depending on the weight and bulk of the component, you'd likely do one out of three (at this depth; in shallower waters, you have more options) a) Small-ish items are simply dropped in a basket attached to the ROV doing the recovery, then brought back to the surface with the ROV. b) Larger items may be handled by the ROV to a basket suspended from a winch, then hoisted to the surface. c) If the items are too large for the ROV to handle, it will be used to attach a sling to the item, which is then in turn attached to the hook of a crane/winch, before being hoisted to the surface.

dbancajas 3y ago
and why did they do this? who paid for this recovery?
- lb1lf 3y ago
  In the cases I've been involved in, it has largely been oil companies or their subcontractors footing the bill, occasionally scientists or, uh, treasure hunters. (I work for a company making this exact type of recovery gear, so every now and then I have to do some field work)
- csb6 3y ago
  The U.S. Coast Guard is investigating the cause of the incident, so they are collecting evidence.
jayrot 3y ago
The Navy also has the FADOSS, though it wasn't needed here I believe. It can lift insane amounts, at insane depths. https://en.wikipedia.org/wiki/Flyaway_Deep_Ocean_Salvage_System https://en.wikipedia.org/wiki/Flyaway_Deep_Ocean_Salvage_Sys...
- lb1lf 3y ago
  -This was interesting, thanks! It appears they utilize a passive system to dampen the effect of vessel movement, whereas in many (most?) other cases compensation is done actively by the traction unit (the twin drums with the rope looped over them in the center of the photo) and the storage winch (bottom) being wired to an accelerometer installed on the vessel. I guess the navy uses the passive system as it will be good enough and does not require that you spend time figuring out the vessel geometry to input the data into the winch control system - which is just another source of problems when you're in a hurry. I like this, it seems they've made the kit as simple and robust as possible while still fulfilling its intended purpose.