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lines of the turret mooring system to the FPSO vessel. Mooring
loads are transferred from the chainhawse connection points
through the chain-table structure to the turret cylinder, and via the
vessel friction pads and main weathervaning bearing into the
ship’s structure. The chain-table also provides the entry points for
the product risers and houses the foundations for the bend
restrictors (as required).
The chain-table deck, which is approximately 1.5 meters
deep is formed of welded steel plates. The deck consists of an
external support ring box for the chainstoppers and a clear central
opening which allows the entry of the risers and free passage of
water flow in and out of the turret.
Chainstoppevs and Chainhawses
Nine (9) chain hawse supports, each consisting of two cast
steel pieces having a hook shape, are welded to the chain-table
deck. The chain hawse assemblies complete with automatic
chainstoppers are fitted into the hooks via a self lubricated bearing
which allows the chain hawse to rotate and align with the chains.
A tubular guide trumpet ensures proper alignment of the chain
during tensioning and helps the articulation of the chainhawses.
This system allows the chain to be hauled in when the
mooring line is pulled, and to be locked as soon as the tension is
released. The chain hawse and the automatic chain stoppers are of
a design, which has successfully used on previous projects and
reduces the time to hook-up the FPSO vessel to the preinstalled
anchorlines.
The bearings of the chain hawse shafts are formed of low
friction material, designed for full operational lifetime of the
system, to allow rotation about a horizontal axis, which is
perpendicular to the chain. This articulation allows the chain
hawse assembly to pivot and thus minimise the interlink
movements that are experienced by the top of anchor chain,
virtually eliminating wear and chafing.
Turret Cylinder
This structure is the principal support element of the deck’s
turret section. It is supported from the main roller bearing and
constitutes a circular stiffened shell member approximately five
metres diameter, which extends from the chain-table up through
the total hull depth. At the main deck level, a circular penetration
allows the turret cylinder to continue until approximately four

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