NEWS AND COMMENT

BRUCE DENNLA - LOCKED-DOWN DENNLA RECOVERY FROM SAND OR STIFF CLAY.

  1. Receive chaser pendant from MODU and secure in shark's jaw.
  2. Connect 1st work-wire to chaser pendant.
  3. Haul in on 1st work-wire to take load off shark's jaw and then lower shark's jaw.
  4. Pay out length of 1st work-wire equal to 1. 05 times water depth at the embedded anchor while boat tows chaser towards anchor.
  5. When the load in 1st work-wire starts to increase, as the chaser reaches the inverse catenary of the anchor fore-runner at the mud-line, stop the boat.
  6. If using a conventional ring chaser, haul in on 1st work-wire to raise the chaser about 25m off seabed and brake 1st work-wire.
  7. Instruct MODU winch to haul in anchor line to utilise high uplift enforced by the suspended chaser to break the anchor forwards out of the seabed.
  8. If using a Bruce bight-lock chaser, instruct MODU winch to pay out 50m of anchor line and haul in on 1st work-wire to raise the chaser about 25m above the seabed and brake 1st work-wire.
  9. Move boat towards MODU to cause anchor line bight leg on MODU side to engage in the jaw of the bight-lock chaser.
  10. Apply boat power in direction of MODU to transmit tension in 1st work-wire directly to the anchor via the locked-on chaser to utilise high uplift to break the anchor forwards out of the seabed then reduce boat power and stop the boat. .
  11. Turn boat to head away from MODU and apply power to seat chaser on the chaser stopper, seen as an increase in 1st work-wire tension, then haul in on 1st work-wire until chaser pendant is on deck and chaser chain is on stern roller.
  12. When chaser chain appears on roller, veer boat to bring anchor line parallel with roller before chaser reaches roller to ensure that chaser traverses roller on its side.
  13. As the anchor comes over the roller, adjust veering of boat to keep the anchor line clear of the anchor.
  14. Bring anchor up deck and veer boat to bring anchor line over shark's jaw.
  15. Raise shark's jaw and pay out 1st work-wire until anchor line is held in shark's jaw then stop 1st work-wire.
  16. Pass a tugger slip line through anchor shackle.
  17. Haul in on 1st work-wire to take load in anchor line and then lower shark's jaw.
  18. Veer boat heading to bring anchor line alongside anchor fluke stabiliser.
  19. Pay out 1st work-wire and tugger slip line simultaneously to bring anchor onto roller.
  20. As anchor starts to topple over roller, slow pay out speed of 1st work-wire to allow weight of anchor to straighten the connection between stopper and anchor then stop all pay out.
  21. With anchor weight taken by 1st work-wire, slip tugger line off anchor shackle.
  22. Pay out 1st work-wire to lower anchor over roller and bring chaser onto roller.
  23. Veer boat to hold chaser on its side as it passes over the roller and stop 1st work-wire when chaser chain is on roller.
  24. Veer boat to bring chaser chain over shark's jaw.
  25. Raise shark's jaw.
  26. Pay out on 1st work-wire until load in chaser chain is taken by shark's jaw and then stop 1st work-wire.
  27. Back up boat to MODU as MODU winch hauls in anchor line.
  28. When boat is less than chaser pendant length off the MODU, hold boat position and lower shark's jaw to transfer tension control to 1st work-wire.
  29. Pay out on 1st work-wire as MODU winch hauls in anchor with paying out and hauling in speeds matched.
  30. When the mark on the anchor line is aligned with the corresponding mark on the MODU (verified by the MODU winch operator), pay out on the 1st work-wire to bring the anchor shackle into contact with the MODU bolster bar and then stop1st work-wire with the chaser pendant slack.
  31. The MODU winch now hauls in slowly on the anchor line to pull the anchor shank up over the bolster bar. The Dennla turns automatically to bring the flat side of the shank against the bolster bar and then the racking nibs on the fluke into engagement with the bolster bar. The MODU winch now stops and applies the brake with about 20mT tension to hold the Dennla securely on the bolster bar.
  32. Veer boat to bring chaser pendant over shark's jaw.
  33. Raise shark's jaw.
  34. Pay out 1st work-wire until chaser pendant is held in shark's jaw and then stop 1st work-wire.
  35. Disconnect 1st work-wire from chaser pendant and haul clear.
  36. Receive MODU crane line and connect to chaser pendant.
  37. Lower shark's jaw as MODU crane picks up chaser pendant for storage on MODU.