ALOHA CABLED OBSERVATORY

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ALOHA CABLED OBSERVATORY

• PHASE I INSTALL
• USNS ZEUS
• FEBRUARY, 2007

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PHASE 1 DEPLOY
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The Zeus is US Navy cable repair ship operated
under contract by civilians. The ship is 513
feet long and displaces 14,250 LT. Berthing for
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NSF contracted for the use of the Zeus for ten
days for the ALOHA cable work for about
150,000. We loaded at Pearl Harbor on Friday
February 9, and sailed on Sunday afternoon,
February 12 for Station ALOHA.
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Cables Near Station ALOHA
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The first task was to cut the HAW-4 cable in a
place where no damage would be done to other
cables. The tension in the cables is too high to
bring them to the surface at these depths.
Despite this, the cable wasn't cut until it
reached a depth of less than 400 fm.
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All cable and rope work on Zeus is done through
linear winches with rope and cable stored BY HAND
in large bins. Tension is taken on one of four
huge drums on which the rope or cable is wrapped
three times.
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Imagine moving 4,000 fm (about 8 km) up and down
this way EACH LOWERING!
We did this four times with rope, hauled in and
redeployed 20 km of cable, and rope-lowered the
cable to the bottom.
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The second task was to recover the Oahu-end of
the cable. This took three tries, dragging hooks
across the bottom trying to snag the cable. Since
each try takes about 12 hours at this water depth
(4,700 m), it cost us a day of ship time extra
over the time expected.
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The cable is recovered at least 1 ocean-depth
back from the cut point so that it doesn't slip
off the hooks on the way to the surface. After
recovery, both ends are tied off, and cut. The
"good" end is determined by OTDR after making a
quick fiber termination.
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The scrap-end was then cut loose (about 7,000 lbs
tension).
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One of the fiber pairs was terminated and the
Makaha Cable Station tested the system for 15
minutes, and light levels were measured.
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The strength members are fanned out in a cone to
provide mechanical strength.
The polyethylene jacket enclosing the fibers is
stripped off using a heat gun.
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Fusion Splicing the fibers from the cable to the
observatory.
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The entire case is then coated in polyethylene
using an injection mold. The molded product is
then x-rayed to insure that there are no air
bubbles.
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The final casting.
The splice is then enclosed in a beryllium-copper
case and rubber shield.
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It took more than 4 hours to lower the package to
the bottom at Station ALOHA, and data were
collected to monitor the package depth. The time
when bottom was approached is expanded in the
next slide.
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As soon as the package hit bottom, the hydrophone
quieted down and the 3.5 kHz pinger and 12 kHz
EM120 were heard.
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Humpback vocalization recorded on Friday, March
2, 2007, at the ALOHA Cabled Observatory at 0615.
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Lots of humpbacks recorded Friday, March 2,
2007, at 1140 AM.
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March 2, 1300 HST. Humpbacks with Sperm whales
that make loud clicking sounds. These sounds went
away later in the day.
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FUTURE