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FLIP
can be used in either a drifting or moored mode, based on the science
requirements, and FLIP can remain on station in the vertical position
for substantial periods of time. For research requiring a stationary rather
than drifting platform, a deep moor capability has been developed.
The first mooring made from a single moor was in 5500-meter water north
of Hawaii in 1969. Subsequently, a multiple anchor capability evolved.
It is now possible to place FLIP in a three-anchor mooring in virtually
any depth of water; in September 2001, FLIP was moored in a water depth
of 4242 meters, 250 miles southwest of Oahu, Hawaii.
Deep-water moorings usually take one day, from first light to past dusk,
in waters 4,000 to 5,000 meters deep. About 80 tons of gear aboard the
tow vessel is required for a deep mooring. Moorings in 4,000-meter water
with a mooring scope of 1.5 have had watch circles in the range of 80
to 200 meters, depending on currents. The mooring lines are recovered
and reused whereas the anchor and anchor chain (ten tons per leg) are
left on the bottom.
Three point moorings in the deep ocean are routine operations, especially
for deployment of acoustic arrays in which flow noise must be minimized
and acoustic navigation of array elements is required. The transponder
system for doing Array Element Location (AEL) can be surveyed in and tied
to the GPS navigation system with the GPS receiver aboard FLIP.
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