Offshore lift platform

An offshore lift platform comprises a platform proper with a plurality of pport legs arranged shiftable. Each leg is retained through the intermediary of latch hole rows arranged in horizontal and vertical spacings and advance means climbing in increments in that at the platform in the spacing of the latch hole rows upper and lower latches are arranged above one another. The lower latches are stationarily positioned at the platform. The upper latches are arranged height-adjustable relative to the platform via a positioner and are interconnected via a ring. The ring is formed by individual segment-like ring portions which are pivotally connected to one another. Each ring portion receives an upper latch. The lower latches are arranged height-adjustable via positioners.

BACKGROUND OF THE INVENTION 
This invention relates to an offshore lift platform, comprising a platform 
proper with a plurality of support legs arranged shiftable, each leg being 
retained through the intermediary of latch hole rows arranged in 
horizontal and vertical spacings and advance means climbing in increments 
in that at the platform in the spacing of the latch hole rows latches are 
arranged above one another and the lower latches are stationarily 
positioned at the platform, whereas the upper latches are arranged 
height-adjustable relative to the platform via a positioner and are 
interconnected via a ring. 
Mobile offshore structures of this type correspond to the so-called "jack 
up" principle, the platform being built as buoyant body and the legs or 
columns being held in the or at the platform via latches and being movable 
in vertical direction via advance means. For doing so, the latches in the 
upper row are withdrawn from the sockets of the legs and shifted by means 
of hydraulic cylinders into the next higher or lower latch hole row. 
Subsequently, the lower row of latches is withdrawn from the sockets, and 
by means of the hydraulic cylinders a corresponding movement of the 
platform is effected, and the latches are reengaged with the leg. 
Such apparatus are already known from German Auslegeschrift No. 2,549,746. 
It has been noted, however, that for large dimensions of the legs it is 
extremely difficult and very costly in manufacturing aspects to in 
particular tolerate the vertical spacings of the latch hole rows so 
closely as would be required in order to achieve a uniform loading of the 
individual latches. 
SUMMARY OF THE INVENTION 
It is the object of the present invention to avoid this disadvantage and to 
provide an offshore lift platform which maintains the required 
manufacturing tolerances of the spacings of the latch hole rows in 
economically acceptable limits and insures a uniform flux of force from 
the legs via the latch hole walling and latches to the platform. 
According to the invention, it is provided for that the ring is defined by 
individual segment-like ring portions and each ring portion receives an 
upper latch, and that the lower latches are arranged height-adjustable via 
positioners. 
It is permitted by this arrangement of effecting an adaptation to the 
spacings and in doing so causing a uniform loading of the latches. 
For a simple configuration of the pivot connection, it is furthermore 
proposed that the pivot connection between adjacent ring portions is 
defined by respectively parallel shiftably arranged slide blocks and 
interconnected by a link. 
A further advantage of the invention that the lower latches are arranged 
height-adjustable via short-stroke cylinders arranged at both sides. 
In order to provide for a uniform load distribution for all latches, it is 
proposed that the positioners for the upper and lower latches are formed 
as hydraulic cylinders and each latch row is interconnectible.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
FIG. 1 shows an offshore lift platform according to the invention which 
substantially comprises a platform proper 1 and a plurality of shiftably 
arranged support legs 2. Each support leg 2 possesses horizontal and 
vertical latch hole rows. At the platform 1, stationarily lower latches 3 
(FIG. 2) as dead-stroke latches or stationary latches are provided. 
Furthermore, upper latches 4 are arranged height-adjustable relative to 
the platform 1 via a hydraulic cylinder 5 and operate as work-stroke 
latches and are interconnected via a ring 6 as shown in FIG. 3. The ring 6 
is defined by segment-like ring portions 7, each ring portion 7 receiving 
an upper latch 4. Each upper latch 4 is retained via a transverse yoke 13 
and operable via control cylinders 14 arranged at both sides. 
The individual ring portions 7 are intercoupled via a pivot connection in 
that each ring portion 7 has slide blocks 9 (FIG. 4) arranged parallel 
shiftable in a guide 8, said blocks being interconnected by a link 10. 
The lower latches 3 are arranged height-adjustable via short-stroke 
cylinders 11 arranged at both sides (FIG. 2). 
The lowering of each support leg 2 relative to the platform 1 is effected 
as follows: 
The ring 6 connected to the leg 2 via the upper latches 4 is moved 
downwardly in direction of the upper deck of the platform 1 by retracting 
the hydraulic cylinder 5. After the hydraulic cylinder 5 has reached its 
extreme position, the lower latches 3 are connected to the sockets 12 of 
the next row of holes. Subsequently, the upper latches 4 are disengaged so 
that the ring 6 is released from the leg 2. By extending the hydraulic 
cylinder 5, the ring 6 is moved upwardly until its upper extreme position 
is reached. Then the upper latches 4 are again connected to the leg 2 via 
the sockets 12, and the lower latches 3 are released again, so that the 
same cycle is repeated. 
When the columns have been extended so far that they have settled on the 
sea floor, upon continuation of the movement procedure described the 
buoyant body is lifted out of the water. It is of course required that the 
vertical pitch of the latch hole rows corresponds to the stroke length of 
the hydraulic cylinder 5. 
Subsequently, by an interconnection of the hydraulic cylinders 5 or the 
short-stroke cylinders 11 it is provided for that all upper latches 4 or 
lower latches 3 are uniformly loaded and thus each latch receives the same 
loading. 
The invention may be embodied in other specific forms without departing 
from the spirit or the essential characteristics thereof. The embodiment 
therefore is to be considered in all respects as illustrative and not 
restrictive.