As one non-limiting example, a foldable mast assembly for a sailing vessel is provided. The foldable mast assembly includes a lower mast section; an intermediate mast section having a lower end foldably coupled to an upper end of the lower mast section; an upper mast section having a lower end foldably coupled to an upper end of the intermediate mast section; and a boom coupled to the lower mast section. A locking device internal the mast assembly is also provided to inhibit folding of the mast assembly.