being disposed on an inner perimeter of a hole in a hull of the watercraft for holding the flexible tube a convex portion of the flexible tube engages at least one concave portion of the flexible member around substantially the entire circumference of the flexible member allowing for easy insertion and removal of the flexible tube from the flexible member application_number US 97258604 A description fig1 and 2 illustrate a personal watercraft 10 that includes a duct structure configured in accordance with a preferred embodiment of the present invention although these features are illustrated in connection with a personal watercraft the features can be used with other types of watercraft as well such as for example but without limitation small jet boats and other suitable watercraft the following describes the illustrated watercraft in reference to a coordinate system in order to ease the description of the watercraft 10 a longitudinal axis extends from bow to stem and a lateral axis extends from port side to starboard side perpendicular to the longitudinal axis a vertical axis extends perpendicular to both the longitudinal axis and the lateral axis and in fig1 and 2 a label u201c fr u201d has been included which designates a forward direction for reference purposes with reference to fig1 and 2 the watercraft 10 includes a hull 12 having a lower hull 14 and a deck 16 the lower hull 14 and the.