Patent ID: 7509919

Claim:
An installation vessel which includes a hull with a periphery formed by bow and stern ends and port and starboard sides, wherein said vessel has an upper working deck with a flat working surface area of at least one hundred meters 2 , wherein: said vessel has a lower working deck with a flat working surface area of at least one hundred meters 2 , said lower working deck having a covered lower deck portion of an area of at least one hundred meters 2 lying at least 1.8 meters directly below said upper working deck, and said lower deck having an open lower deck portion which extends rearward beyond said upper working deck and which has an area of at least one hundred meters 2 that extends to the periphery of the vessel hull; said bow and stern ends form longitudinally spaced vessel front and rear ends, said vessel has a middle lying halfway between said vessel front and rear ends, and said vessel has a rear half extending longitudinally from said middle to the rear end of the vessel; said upper deck extends rearward of said vessel middle by a length that is a majority of the length of the rear half of the vessel, and said open lower deck portion extends at least 10 meters rearward of said upper deck rear end.