BACKGROUND OF THE INVENTION This invention relates to a jack-up platform locking 5 apparatus。 More specifically this invention relates to an apparatus for locking an offshore platform deck with respect to a vertically adjustable leg ot the platforiri independently  of  a  platform  jack-up  drive assembly。82310

In the past, offshore platforms or towers have been extensively utilized  around  and  upon  the  continental shelf regions of the world。 Examples of offshore plat- form  installations  include  supports  for  radar  stations, light  beacons,   scientific  and   exploration  laboratories,

chemical  plants,  power  generating  plants,  etc。  Princi-    15

pally, however, offshore platforms  have  been  utilized by the oil and gas industry in  connection  with  oil and gas  drilling,  production   and/or  distribution operations。

In conducting such offshore activity several platform designs have been utilized in the industry。 In deep water 20 applications,   semi-submersible   or   floating   drill ships

which  are dynamically  positioned  and/or turret moored over a well site have been effectively  utilized。  In  shal- lower water applications fixed length towers have been fabricated on shore and either transported  in a horizon-  25 tal posture to an offshore site by barge or towed upon bouyancy chambers within the  tower  legs。 On  site the tower is pivoted  into an upright  posture  and  the base of

the tower legs are positioned  into firm engagement   with

gree of  undesireable  slack  or vertical  mobility  between

the legs and platform。 Such mobility may prove to be disadvantageous when the platform encounters envi- ronmental hydrodynamic and aerodynamic loading。 More specifically platform legs typically comprise a set of three or more vertical chords which are intercon- nected and strengthened with “K” or “X” type bracing。 As previously mentioned the legs extend through wells fashioned within the platform deck and peripherally pass adjacent bearing surfaces at the upper and lower surface of the deck。 Tolerance within some jack-up mechanisms, combined with bending moments encoun- tered from environmental loading, tends to displace the legs into abutting lateral contact with the upper and lower surfaces of the deck。 Accordingly typical plat- form legs must be overdesigned to carry lateral reaction forces at locations intermediate the junctions of the “K” or “X” type bracing。

In a similar vein present jack-up systems are fabri- cated with large structural members in order to with- stand and react against environmentally imposed mo- ments。 The structural size of these members needed to safely react peak statistical moments adds a  consider- able degree of dead weight and cost to the overall plat- form design。

The difficulties suggested in the preceding are not intended to be exhaustive,  but  rather  among many which may tend to reduce the effectiveness and owner satisfaction  of  prior jack-up  offshore  platform systems。

the seabed。 A platform  deck is then fabricated  upon  the  30 Other  noteworthy  problems  may  also  exist;   however,

erected tower for conducting offshore operations。 Such

fixed platforms require considerable time to  assemble and  once  in  position  are difficult  to relocate。

One platform design which combines many of the advantages of floating and fixed equipment  is known  as a “jack-up platform”。 In this connection a barge or self-propelled deck, operable to function in a conven- tional flotation capacity during transportation, is fitted with extendable legs which are deployable on site。 More specifically, the hull/deck carrying one or more jack-up legs is either towed or navigated to a desired offshore site and the legs are jacked through wells in the deck into firm supporting engagement with the water bed。  Further  jacking  serves  to  raise  the  deck  with re-