Abstract: A lower deck for a watercraft is attached to and supported by an amidships hull, and an actuator slides the lower deck and amidships hull between a stowed position and an extended position on guide rails that are secured to the underside frame of the upper deck that is supported by abeam hulls. When fully extended, the lower deck remains attached to the watercraft while a portion of the lower deck's aft section and the aft end of the amidships hull remains beneath the upper deck. A pair of side beams respectively connect to a port side and a starboard side of the lower deck or the amidships hull. Sliding members, such as rollers and/or guide bars respectively connect to the guide rails, and the side beams respectively engage and slide on the sliding members.

Abstract: A lower deck for a watercraft is attached to and supported by an amidships hull, and an actuator slides the lower deck and amidships hull between a stowed position and an extended position on rails that are secured to the underside frame of the upper deck that is supported by abeam hulls. When fully extended, the lower deck remains attached to the watercraft while a portion of the lower deck's aft section remains beneath the upper deck. A hold within the amidships hull can store accessories used with the watercraft, such as live wells, tables, seats, a foldable slide and ladder assembly, and other items which can be accessed and deployed when the lower deck is extended. The holds are covered by panels which may be individual separable panels, a foldable set of connected panels, or laterally expandable panels. The lower deck can have foldable handrails and recessed cup holders.

Abstract: An extendable and retractable lower deck for a watercraft is attached to and supported by one or more amidships hulls. The lower deck and hulls slide between an extended position and a stowed position on rails that are secured to the underside frame of the main, upper deck that is supported by abeam hulls. When fully extended, the extendable deck remains attached to the watercraft. A rotatable gate positioned within the lower hull can be used for improved accessibility to and from the water; the gate is stowed when its distal end is in the raised position and is deployed when its distal end extends below the bottom side of the hull into the water in the lowered position. Laterally expandable panels in the lower deck provide increased width, and other accessories used with the watercraft can be contained in one or more storage holds in the amidships hull.

Abstract: An extendable and retractable lower deck is supported by one or more longitudinally extending hulls. The lower deck slides between an extended position and a stowed position on rails that are secured to the underside of an upper deck of a houseboat, pontoon boat, tritoon boat, catamaran, floating dock, pier-supported dock or other watercraft or dock. When fully extended, the floating deck remains attached to the watercraft, and additional width may be achieved with laterally expandable panels in the lower deck. Various accessories are connected to the lower deck or to a storage hold in the hull beneath the lower deck, such as a pool liner insert, a hot tub liner insert, a slide and ladder assembly, a seat and mounting bracket assembly, a volleyball net and pole assembly, an umbrella and pole assembly, a hammock and stand assembly, a seat lift, and an expandable deck insert.