A multi-part kayak whereby the kayak body is hollow and void of a center where a traditional sit-on-top kayak cockpit would reside. The kayak body thus having a centralized hole therethrough. Surrounded by the hollow perimeter body the design is best analogous to a doughnut with a hole in its center. The kayak perimeter body is designed to accommodate multiple central hulls which can additionally accept multiple cockpit configurations via insertion into the central hull. Additionally such arrangement provides removable central hulls to be affixed in a manner whereby no mechanical fasteners or points of possible water intrusion exist below the waterline. Means are provided so as to prevent occupants weight from forcing the removable central hull downward through the kayak body and from wave action forcing the removable central hull upward through the kayak body. One kayak body can accommodate multiple configurations of removable central hulls thereby eliminating the need for various kayaks to perform various functions. Additionally, the cost of shipping multiple boats is reduced as sales outlets can order a limited number of kayak bodies and multiple central hull arrangements and satisfy the needs of multiple clients. Lastly the ability to replace a kayak body or central hull extends the life of the kayak by providing a means of replacement for damaged hull components rather than replacing an entire kayak.

A multi-purpose sailing kit assembly including at least one, and preferably two separate hulls. Each of the hulls further includes first and second elongated, buoyant and self-contained halves which are pivotally secured together along a longitudinal direction. Each of the pairs of hull halves further include first and second longitudinal and perpendicularly extending planar surfaces such that the halves may be converted from a first cross sectional profile to a second cross sectional profile. Coupling mechanisms are provided for engaging within selectively formed circular openings in the planar surfaces of the hull halves and locking engage the hull halves together in the desired cross sectional profile. A frame is provided and secures first and second convertible hulls together in a spaced manner or, alternatively, supports outriggers in a spaced manner relative to a single hull. A sailing mast is capable of being mounted to a location of the upwardly facing surface of a selected hull halve or to a specified location along the frame.

A seat for a watercraft provides a separately adjustable thigh support and back support. The seat includes a pelvis support and a separately positionable thigh support pivotally mounted on the pelvis support. An adjustable back support includes a post pivotally mounted to the pelvis support and a backrest that moves vertically on the post. Means are provided for adjusting and setting the thigh support and back support at desired positions for optimal support and comfort. Preferably, a person can adjust the seat while fully seated in the seat.

A seating system for use in a watercraft is disclosed. The seating system comprises a seat pan adapted to be mounted to the watercraft, a pad coupled to the seat pan and adapted to provide a seating surface for the user, and a back rest coupled to the seat pan. The seating system further comprises a first adjustment mechanism configured to provide for and aft adjustment of the seating position, a second adjustment mechanism configured to provide adjustment of the back rest without having to exit the watercraft, and a third adjustment mechanism configured to provide adjustment of the seating surface.