2009/09/17
Labels: ropos, thompson, deployment, showcomments, installation, cable
One step forward...
On 16 September 2009, elation and a setback transformed the R/V Thompson fantail deck into a beehive of activity. After high winds and seas forced us to forego our planned cable lay at ODP 1027, we retreated to ODP 889, where relatively milder seas allowed a quick reconnaissance and troubleshooting dive.
We were quickly rewarded for this decision when, working with our shore station, we found and eliminated a ground fault that had shut down the instrument platform and connected bottom pressure recorder at this location. We were thrilled with this discovery. It meant we could proceed with installation of three important instruments at ODP 889. The news spread quickly and soon the deck was thronged with crew and technicians readying the instruments for deployment.
...one step back.
But the excitement was short-lived. During recovery of ROPOS, the umbilical cable somehow became looped, resulting in a severe kink. The cable was badly damaged and could no longer be used. The only option was to shorten the cable, cutting off the damaged section, and re-terminate it.
The Problem |
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A damaging kink in the ROPOS umbilical cable developed during recovery to ship. This kink required ROPOS to cut the cable and re-terminate it before installation work could proceed.
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Around 100m of umbilical cable had to be removed after a damaging kink rendered it unusable, 16 September 2009.
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(Click the images to view slideshow.)
ROPOS Umbilical: More than meets the eye
The ROPOS umbilical cable is unique because it is built not only to carry a heavy load, but also electricity and fibre optic communications to the vehicle. Sealed within the cable core are five main power lines, 6 steel-sheathed fibre lines and a number of auxiliary lines. This flexible inner cable is armoured with two helical wraps of high-strength steel wire.
Inside the Umbilical |
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The ROPOS umbilical cable encases a bundle of separate electrical and fibre optic communications cables. All had to be re-terminated and reconnected to their respective terminals on ROPOS.
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(Click the image to enlarge.)
Saws, drills, chisels...
The cable passes into ROPOS through the lifting-point bullet, a heavy steel cone that fits onto a hinge atop the vehicle. To shorten and re-terminate the umbilical cable, the damaged portion had to be cut off and removed from the lifting-point bullet – a task easier said than done. When asked how to do this, crew member Dan Cormany replied, "patience, power-tools, some swearing and cussing."
The Extraction |
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After considerable effort, ROPOS crew member Dan Cormany was finally able to drill, pound, twist, chisel and yank the old cable plug out of the lift point, 16 September 2009.
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ROPOS crew member Dan Cormany cuts the old cable end from the lifting point bullet, 16 September 2009.
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ROPOS crew member Dan Cormany drills the old cable out from the centre of the lifting point bullet, 16 September 2009.
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(Click the images to view slideshow.)
Refilling the Bullet Cone
Once cleared, the new section of cable had to be cemented into the bullet. ROPOS crew members did this by splaying the shield wires, arranging them in the cone, and filling the cone with a quick-setting glue called wirelock.
The Goop |
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ROPOS crew member Jonathan Lee spectates as Dan Cormany (left) and CSSF general manager Keith Shepherd (right) pour wire lock into the lifting point bullet, 16 September 2009.
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Once the lift point bullet was cleared, the shielding wires were splayed and arranged in the cone-shaped cavity , which was filled with wirelock.
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(Click the images to view slideshow.)
Rewiring ROPOS
Once the weight-bearing portion of the cable was re-set in the lifting-point bullet, the inner electrical and fibre optic cables were then routed to their required terminals within the ROPOS termination box. Then all sub-systems had to be tested.
Wires |
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ROPOS crew members Jonathan Lee and Kim Wallace (beneath the white hardhat) work on ROPOS electrical and communications wiring, 16 September 2009.
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ROPOS crew member Kim Wallace ducks too slowly to avoid the camera shutter, 16 September 2009.
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(Click the image to enlarge.)
Success!
This intensive activity was accomplished skillfully by the ROPOS team during the afternoon of 16 September 2009. Meanwhile NEPTUNE Canada scientists, technicians and students worked alongside them, readying the ODP 889 instruments for deployment.
