Boat lifting gantry crane

A boat lifting crane comprising:

• an upper frame having two upper beams,
• at least two pairs of carriages, each carriage of each pair being mounted so that each carriage is configured to move on a respective upper beam and is configured to translate for a respective stroke portion,
• at least one lifting belt extended between two carriages of a same pair of carriages,
• wherein at least part of the stroke portion of a carriage of one of the pairs of carriages is superimposed on at least part of the stroke portion of a carriage of the other of the pairs of carriages, the stroke of each carriage of the pairs of carriages being only limited by two stroke limit positions that are defined by space occupation of other carriages disposed on the respective upper beam also in an operative condition, wherein each of the carriages comprises an upper base coupled to the respective upper beam, and a lower portion coupled to the respective lifting belt, each carriage being further provided with coupling elements with adjustable extension configured to adjustably couple the upper base to the lower portion, wherein the coupling elements comprise:
• a first pulley assembly associated with the upper base;
• a second pulley assembly associated with the lower portion;
• and
• a cable engaged by the first and second pulley assemblies,
• and further comprising an adjustment system configured to act on said cable of the coupling elements with adjustable extension of each carriage, said adjustment system comprising, for each carriage, first guiding pulleys and a motorized winch for winding the cable, the adjustment system being configured to vary a length of the cable and therefore vary a distance of the lower portion from the upper base.