Abstract: A submergible vessel for use in shallow-water oil drilling includes a pair of spaced pontoons selectively submergible and raisable in water by the admission and expulsion of water, a main deck, a frame supporting the main deck over the pontoons, and a jacking system for horizontally and vertically translating a packaged drilling rig positioned thereon. The jacking system includes a pair of parallel cantilever beams positioned on the main deck adjacent the stern, vertical jacks for selectively translating the cantilever beams in a vertical direction above the main deck, and horizontal jacks for selectively translating the cantilever beams in a horizontal direction along their longitudinal axes. The deck has an inwardly extending slot formed therein at the stem, and the cantilever beams are positioned on either side of the slot, with their longitudinal axes parallel to the longitudinal axis of the deck.