Telescopic marine derrick structure and method of erecting same

Claim 1

A DERRICK FOR USE IN DEEP WATER, SAID DERRICK COMPRISING: A FIRST SLENDER ELONGATED ELEMENT OF FIXED AND A SECOND SIMILAR SLENDER ELONGATED ELEMENT OF FIXED LENGTH, SAID SECOND ELEMENT SLIDABLY TELESCOPICALLY INTERFITTING WITHIN SAID FIRST ELEMENT FOR EXTENSION AND RETRACTION BY RELATIVE MOVEMENT LENGTHWISE OF SAID ELEMENTS WITH SAID SECOND ELEMENT MOVING THROUGH ONE END OF SAID FIRST ELEMENT; SAID FIRST ELEMENT SEATING CLOSELY ABOUT SAID SECOND ELEMENT AND ENGAGING IT TO GUIDE THE TELESCOPIC MOVEMENTS OF THE ELEMENTS WITH RESPECT TO EACH OTHER; MEANS FOR CHANGING THE SPECIFIC GRAVITY OF ONE OF SAID ELEMENTS WITH RESPECT TO A SURROUNDING BODY OF LIQUID FOR EFFECTING EXTENSION AND RETRACTION OF SAID ELEMENTS IN RELATION TO EACH OTHER; A PLURALITY OF BASE MEMBERS HINGEDLY CONNECTED TO THE OTHER END OF SAID FIRST ELEMENT AND MOVABLE FROM AN EXTENDED DERRICK SUPPORTING POSITION EXTENDING LATERALLY OUTWARDLY FROM SAID ELEMENTS TO A RETRACTED POSITION GENERALLY PARALLEL TO THE LENGTHWISE AXIS OF SAID DERRICK; SAID BASE MEMBERS HAVING A PLURALITY OF COMPARTMENTS THEREIN; MEANS FOR ADMITTING AND EXHAUSTING WATER AND AIR TO AND FROM SAID COMPARTMENTS TO CHANGE THE SPECIFIC GRAVITY OF SAID BASE MEMBERS RELATIVE TO A SURROUNDING BODY OF WATER FOR EFFECTING THEIR MOVEMENT TO AND FROM RETRACTED POSITION.