support column 28 being disposed within a beam bracket 25 the adjustable support structure 20 provides a vertical adjustment for portions or all of the gable assembly 13 the adjustable support structure 20 enables the bow section of the gable assembly 13 to be raised or lowered the stern section of the gable assembly 13 to be raised or lowered or their combination to be raised or lowered similarly the port and starboard sections of the gable assembly 13 can be raised or lowered the preferred angle between the tubes 18 of the gable assembly 13 is 150 u00b0 fig2 c depicts a preferred embodiment of an end view of the gable assembly 13 of fig2 a mounted on a pair of cantilevers 32 and variable centered brackets 34 the cantilevers 32 are secured to the box frame support members 30 by a pair of upper brackets 33 fig2 d depicts an exploded view of a preferred embodiment of an end view of the gable assembly 13 and adjustable support structure 20 of fig2 b tubes 18 are inserted into the end peak fitting 14 and pipe fittings 37 which are in turn attached to the box frame support members 30 the box frame support members 30 are fastened to the support columns 28 with u bolts 45 each support column 28 is disposed within a beam bracket 25 and held in place with a clevis pin 29 the clevis pin 29 can be removed to enable vertical adjustment of the support column 28 within the beam bracket 25 the beam brackets 25 are in turn fastened to i beams 44 of the deck assembly 12 using bolts 41 and beam clamps.