According to Wikipedia: "The LCU 1610, 1627 and 1646 class vessels are operated by the United States Navy. They are a self-sustaining craft complete with living accommodations and messing facilities for a crew of thirteen. They have been adapted for many uses including salvage operations, ferry boats for vehicles and passengers, and underwater test platforms. Each LCU is assigned a non-commissioned-officer-in-charge (NCOIC) (Craft Master) who is either a Chief Petty Officer or Petty Officer First Class in the Boatswain’s Mate, Quartermaster or Operations Specialist rating. These vessels have bow ramps for onload/offload, and can be linked bow to stern gate to create a temporary pier-like structure. "