A self-propelled jack-up vessel has a centreline (CL) extending from a bow end (105) to a stern end (107) of the vessel along a central longitudinal axis, defining port and starboard sides of the vessel. The vessel comprises a hull (102), a deck (103) and four retractable legs (104, 106, 108, 110), which extend through the hull and the deck. The vessel includes a bow leg arranged on the centrelinetowards the bow, a stem leg arranged on the centreline towards the stem, and a starboard leg arranged at the starboard side. The diagonal placement of the legs, with respect to the centreline gives greater stability and flexibility. Further, a vessel is provided having a cruciform primary structural arrangement.