A vang assembly for manipulating a sailboat boom which is hingendly connected to the lower portion of a sailboat mast (12). The vang assembly includes a rigid and unextensive vang (strut) (20) connected both to the mast (12) and to the boom. The first end portion is hingendly attached to the lower portion of the mast below the boom, and the second end portion is hingedly attached to a traveller (26) sliding on track (30) fixed to the boom at a location spaced outwardly from the lower portion of the mast. Traveller fore and aft movements are controlled by block and tackle system. Traveller sliding allows to control boom vertical position. When traveller is pulled forward (toward the mast), the boom is forced upwardly by rigid vang working as a strut, when traveller is pulled aftward (opposite the mast), boom is forced downward by the rigid vang working as a tie rod.