spect to the surface of the body of water and once the 45 lowermost portion of the deck is positioned above a statistical wavecrest height jacking is discontinued and drilling  and/or  production   operations  are begun。

The subject invention is directed to a deck locking apparatus for a jack-up platform such as previously 50 described。

Various designs have been advantageously  utilized  to jack the  supporting  legs  with  respect  to  the  platform deck。 One such design comprises a jacking mechanism having hydraulic cylinders which reciprocate vertically 55 along the legs of the offshore tower and carry horizon- tally actuatable pins at the ends thereof for engagement with apertures positioned  within rails affixed to the  legs。

Another previously known jacking mechanism com- prises one or more racks which longitudinally extend along the operative jacking length of the offshore tower legs。 Pinion gears mesh with the leg mounted racks and are driven by hydraulic or electric drive assemblies mounted  upon  the  platform deck。

Although jack-up platform designs have attained a considerable degree of commercial acceptance, at least some jack-up mechanisms, and particularly the jack-up mechanisms  of  the  rack  and  pinion  type,  permit  a de-

those  presented   above  should  be  sufficient  to demon-

strate that jack-up platform systems particularly of the rack and pinion type appearing in the past will admit to worth-while   improvement。

OBJECTS  OF  THE INVENTION

It is therefore a general object of the invention to provide a novel, jack-up platform locking apparatus which will obviate or minimize difficulties of the type previously  described。

It is a specific object of the invention to  provide a novel jack-up platform locking apparatus wherein the platform deck may be securely connected to the plat- form legs in a raised position independent of the plat- form jacking  assemblies。

It is another object of the  invention  to  provide  a novel jack-up platform locking apparatus wherein envi- ronmentally imposed moments upon the  jack-up  legs may be reacted at secure design  locations  and not through  deck  well guides。

It is a further object of the invention  to  provide  a novel jack-up platform locking apparatus which will enable the structural dead weight of the platform to be reduced while maintaining  statistical  safety  standards for  environmentally  imposed  bending  moments。

It is yet another object of the invention to provide a novel jack-up platform locking apparatus which may be vertically adjusted with respect to the deck and plat- form leg。

It is still another object of the invention to provide a novel jack-up platform locking apparatus wherein a locking mechanism may be horizontally actuated into engagement with the platform legs and  securely  re- tained  in  substantial  load  bearing engagement。

It is a further object of the invention  to  provide  a novel jack-up platform locking apparatus wherein the locking  assembly  may   be  mechanically   secured   in  a

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vertical posture following a vertical adjustment proce- tion。 In this connection FIGS。 1 and 2 depict an off- dure。 shorejack-up platform 10 of the type which may advan-

It is yet a further object of the tnvention  to prOVlde  a tageously  utilize  the  locking  mechanism  of  the subject novel jack-up platform locking apparatus which iS C£I1TI-