Abstract: A plurality of lock bolts are flexibly stacked in a frame at a lesser angle above the horizontal than the frame is slidably mounted in a rack and pinion jack-up rig's horizontal part. The steeper frame mounting angle reduces sliding friction by the vertical component of gravity. The flatter mounting angle of the lock bolts increases bolt locking efficiency that is a maximum at the horizontal. Free ends of the lock bolts project beyond the frame and are adapted to engage and disengage with the rack of the rack and pinion jack-up rig, the rack being oppositely mounted on the vertical part thereof. The frame is slidably actuated by an hydraulic cylinder pivoted to the horizontal part and the frame. The projecting free ends are roughly wedge shaped for engaging with the rack, and have arcuate lower engaging surfaces and flat upper engaging surfaces, the last of which extend from respective vertical abutments to define a steeper angle than opposing rack engaging surfaces.

Abstract: A stationary gear is keyed to a center shaft which is supported longitudinally in a frame. Gears identical with the stationary gear mesh therewith as equally spaced satellites therearound. The satellite gears are fixed on respective satellite shafts, which are mounted for rotation in and between a pair of longitudinally spaced plates that are mounted for rotation on the center shaft. Cylinders, on which are defined helical grooves for engaging a line, are keyed to the respective satellite shafts for rotation therewith. The helical grooves of the respective cylinders have a transverse pitch angle per revolutions of the respective cylinders and plates that is a function of the distance between centers of adjacent cylinders and the center angle subtended thereby, the common diameter of center and cylinder gears, and the diameter of the engaging line, that add up closest to "1H" and straight tracking to provide a tracking error of less than 0.1.degree. instead of a usual tracking error of 3.degree..

Abstract: A double-ended, flat-bottomed hull, having a length to beam ratio of approximately 2 to 1+, with sides tapering from amidships to the pointed ends respectively. Two octagonal (in cross-section) end columns and two larger rectangular beam columns are equally spaced around the perimeter of the hull for supporting a work deck thereabove, for providing columnar storage rather than work deck storage and a lower center of gravity, and for eliminating external trussing. The configuration of the hull substantially increases its natural heaving period, and, coupled with an added-mass factor increased by chamfering the hull perimeter between columns and breakwaters mounted on an end and a beam, extend the range of wave height and period range of seas in which the barge can operate and avoid resonance and substantial beam wave effect.