A storage space can be defined above an engine hatch of a hull. A rear end portion of the hatch cover can have an opening into which a seat can be retracted into the storage space. A rear end portion of the seat can define part of the hatch cover when the seat is retracted within the storage space. A rail section can be disposed within the storage space. The seat can be movable between the inside and outside of the storage space by moving along the rail section in a fore to aft direction. Also, a support unit can engage with a bottom end of a guide groove to support the seat when the seat extends from the hatch cover.