Autonomous Reef Monitoring Structures (ARMS) Recovery

Equipment for Dive

  • Recovery crate to encapsulate ARMS tier such as a milk crate lined with a 100 µm mesh or a square 18 Q container (a recovery crate)
  • Knife or shears
  • Tool bag
  • Gear bag with buoyed line attached
  • Floating line with a buoy attached to one end
  • 2 ratchet straps, heavy-duty bungee cords, or cam straps per ARMS unit

*Note the number of recovery crates and buoyed lines brought down should equal the number of ARMS being removed that that site.

Locating the ARMS

ARMS may be challenging to recognize underwater after they've soaked for a period of time. To maximize dive time, it is suggested to first snorkel and free dive around the marked GPS position to find their location. This is especially important if ARMS are being redeployed at the same site. It prevents the divers from having to move the heavy deployment equipment underwater if the gear was lowered on a GPS point that was slightly off site.

Recovery Procedures

  1. Bring recovery crate, tool bag with shears and knives, two ratchet straps or heavy-duty bungee cords, and an extra bag to hold weights, zip ties and stakes after removal. You will also need line(s) longer than the depth to use as a hand-tended recovery line or a lift bag to bring the ARMS unit and weights and stakes to the surface.
  2. Using a knife or shears, remove the zip ties around the weights.
  3. Remove the zip ties attaching the baseplate to the stakes.
  4. When the ARMS unit is free of zip ties and weights, place the recovery crate over the ARMS unit.
  5. Insert ratchet straps through the hand holes on the base plate and back through itself.
  6. Pull or crank the latching straps until the cover is tightly sealed on the ARMS baseplate. You can use bungee cords as long as the tension is high enough to keep a good seal during the rest of the recovery process.
  7. If you are not redeploying a new set of ARMS, remove the stakes and place them along with the weights and zip ties into the gear bag. If you are redeploying ARMS, lift the covered ARMS unit over the stakes and redeploy the new ARMS unit over existing stakes and proceed with installation.
  8. Attach a buoyed line to the ARMS unit for surface recovery. **Note: experienced divers could carry an ARMS unit to the surface during their accent and not attach a buoyed line.
  9. Once back in the small boat, fill up containers full of sea water to place the ARMS into.
  10. Pull up the ARMS units attached to the buoyed lines individually.
  11. Lift the ARMS out of the water and immediately place each ARMS unit in a tub full of seawater with a battery operated aquarium bubbler. If your recovery crate is not mesh lined such as the 18Q container pictured below, remove the crate from the tier in a tub of seawater and add bubblers.
  12. Transport the recovered ARMS to ship or shore station for further processing as soon as possible.