A method of installing an offshore floating structure, wherein the floating structure comprises a floater with positive buoyancy and a keel with negative buoyancy, as well as suspenders connecting the keel and the floater with each other, wherein the floater has a number of floater nodes arranged in polygonal configuration, including a first floater node, a second floater node, and a third floater node, and the keel has a corresponding number of keel nodes arranged in polygonal configuration, including a first keel node, a second keel node, and a third keel node wherein the suspenders are provided in a corresponding number of suspender pairs, each pair comprising a passive suspender and an active suspender, wherein each of the active suspenders connect only one floater node with only one keel node, wherein the first floater node and the first keel node are connected by a first active suspender (440I-I), wherein the second floater node and the second keel node are connected by a second active suspender (440II-II), wherein the third floater node and the third keel node are connected by a third active suspender (440III-III), wherein each of the passive suspenders connect only one floater node with only one keel node, wherein the first floater node and the second keel node are connected by a first passive suspender (420I-II), wherein the second floater node and the third keel node are connected by a second passive suspender (420II-III), and wherein a third passive suspender (420III-I) connects the third floater node with a keel node that is neighbor to the second keel node, wherein this neighbor keel node is the first keel node in the case of the keel only having three keel nodes; wherein the method comprises suspending the keel by the suspenders in a first position at a first depth under water below the floater; wherein the method comprises keeping the suspenders substantially taut while changing the vertical distance between the floater and the keel from the first position at the first depth to a second position at a second depth under water by changing the length of all active suspenders and causing a rotation of the keel relatively to the floater about the vertical direction by maintaining each of the passive suspenders at a fixed length with a fixed distance between its connection point on the floater and its connection point on the keel. wherein the floater has a number of floater nodes arranged in polygonal configuration, including a first floater node, a second floater node, and a third floater node, and the keel has a corresponding number of keel nodes arranged in polygonal configuration, including a first keel node, a second keel node, and a third keel node wherein the suspenders are provided in a corresponding number of suspender pairs, each pair comprising a passive suspender and an active suspender, wherein each of the active suspenders connect only one floater node with only one keel node, wherein the first floater node and the first keel node are connected by a first active suspender (440I-I), wherein the second floater node and the second keel node are connected by a second active suspender (440II-II), wherein the third floater node and the third keel node are connected by a third active suspender (440III-III), wherein each of the passive suspenders connect only one floater node with only one keel node, wherein the first floater node and the second keel node are connected by a first passive suspender (420I-II), wherein the second floater node and the third keel node are connected by a second passive suspender (420II-III), and wherein a third passive suspender (420III-I) connects the third floater node with a keel node that is neighbor to the second keel node, wherein this neighbor keel node is the first keel node in the case of the keel only having three keel nodes; wherein the method comprises suspending the keel by the suspenders in a first position at a first depth under water below the floater; wherein the method comprises keeping the suspenders substantially taut while changing the vertical distance between the floater and the keel from the first position at the first depth to a second position at a second depth under water by changing the length of all active suspenders and causing a rotation of the keel relatively to the floater about the vertical direction by maintaining each of the passive suspenders at a fixed length with a fixed distance between its connection point on the floater and its connection point on the keel.