A monohull offshore drilling vessel includes a hull having a moonpool; a multiple firing line hoist system mounted on the hull at the moonpool and including a mast having a top side and a base connected to the hull, wherein the mast has a hollow construction with a first side and an opposed second side; a first hoisting device having load attachment means displaceable along a first firing line extending on the outside of and adjacent to the first side of the mast; a second hoisting device having load attachment means displaceable along a second firing line, which on the outside of and adjacent to the second side of the mast; wherein the first and second hoisting devices each include cable(s) and associated winch(es), the winches disposed in the hollow construction of the mast, to manipulate the position of each of the load attachment devices relative to the mast.