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catenary anchor leg mooring |
a type of single point mooring which
could be used as an offshore terminal. The system is characterized by
a floating buoy moored to the seabed by 6 to 8 anchor legs laid out in
large scope catenaries. Riser systems or flow lines that emerge from the
sea floor are attached to the underside of the CALM buoy. Some of the
systems use a hawser, typically a synthetic rope, between the vessel and
the buoy. Since the response of the CALM buoy is totally different than
that of the vessel under the influence of the waves, this system is limited
in its ability to withstand environmental condition. When sea states attain a certain
magnitude, it is necessary to cast the vessel off. In order to overcome this limitation, rigid structural
yokes with articulation are used, in some designs, to tie the vessel to the top of the CALM
buoy. This rigid articulation virtually eliminates horizontal motions between the buoy and the vessel.
The predominant use of the CALM system is for offloading operations.
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