US 4,446,807 A · Mooring apparatus for floating vessels

Abstract

A mooring apparatus for a semi-submersible oil exploration and drilling rig includes eight drum anchor hoists and winches on which are carried eight wire rope mooring lines. Each of these lines extends up over one of eight head sheaves and vertically down the outside face of the oil rig through a fairleader rotatably mounted with respect to the rig at a bottom submerged portion thereof. A linear line pull machine is mounted to the rig in encompassing relation to each of the vertical runs of mooring line between the head sheave and the fairleader. These eight mooring line assemblies are distributed around the periphery of the rig. Two mooring lines extend at 90.degree. from each other at each corner of the rig. At least one hydraulic power unit is provided for each two of these mooring line assemblies, and air and hydraulic control means are provided utilizing power from this power unit selectively to: (1) reel out and reel in on the mooring lines when low line forces are involved using the anchor hoist; (2) to exert extremely high forces at slow speeds when necessary to set anchors attached to outer ends of the mooring lines and to positively hold the rig against the upward buoyant effect of the rig's pontoons; or (3) to operatively disassociate the linear pull machines from the mooring lines so that the mooring lines can be reeled outwardly at very high speeds.

A platform-mounted apparatus for drawing in, storing, holding, and paying out a flexible load line having the properties of wire rope and having a load at an outer end thereof, said apparatus including:

A. said flexible load line and its attached load;
B. a power supply mounted with respect to said platform and capable of supplying hydraulic fluid under pressure;
C. winch means including:
(1) a winch frame mounted with respect to the platform,
(2) a winch drum to which an inner end of the load line is attached, said drum being rotatably mounted on said frame,
(3) braking means operably connected between the drum and the winch frame,
(4) hydraulic drum drive means operable to rotate the drum to move the load line in a first direction as it winds on the drum, the drum drive means being operable selectively to power the drum
(a) in a slow speed/high torque range, or
(b) in a high speed/low torque range, and
(5) fluid operable brake control means to cause the braking means selectively to
(a) let the winch drum run free,
(b) to retard rotation of the winch drum, or
(c) to stop it and to hold it against rotation with respect to the winch frame;
D. a hydraulically operable linear load line pull machine mounted with respect to the platform and encompassing a straight run of the load line between said winch drum and said line load, said linear load line pull machine including:
(1) a linear line pull machine frame mounted with respect to the platform,
(2) wedge shape gripper jaws slidably mounted on said pull machine frame and adapted to releasably grasp the encompassed portion of the load line to hold it against movement in a second direction opposite the first direction of movement of the load line when it is wound on the winch drum,
(3) hydraulic linear pull drive means operable when applied with hydraulic fluid under pressure to move said jaw means reciprocally with respect to said pull machine frame
(a) to cause the load line when grasped by the jaw means to move in the first load line direction and
(b) to move in the jaws in a second direction, and
(4) hydraulic gripper motor means operable in a disengaging direction to disengage said jaw means from said load line and in an engaging direction to cause said jaw means to grasp said load line;
and
E. control means selectively operable to:
(1) supply hydraulic fluid under pressure from the power supply to the drum drive means and actuate the drum drive means into its high speed/low torque range, actuate the gripper motor means in the disengaged direction, and actuate the brake control means to release the braking means, or
(2) supply hydraulic fluid under pressure from the power supply to the drum drive means and actuate the drum drive means into its low speed/high torque range, actuate the gripper motor means in the disengaged direction, and actuate the brake control means to release the braking means, or
(3) actuate the gripper motor means in the engaged direction to position the gripper jaws to grasp the load line, supply hydraulic fluid under pressure from the power supply to the drum drive means and actuate the drum drive means into its high speed/low torque range, supply hydraulic fluid under pressure from said power supply to said linear line pull drive means, and actuate said brake control means to release the braking means.

22 more elements

Mooring apparatus for floating vessels

Life of this patent

Mooring apparatus for floating vessels

Life of this patent

Abstract

Claims2