Abstract: In a preferred embodiment, a sail-boat type wind-surfing catamaran as a kit of disassembled parts having inflatable deflated pneumatically-sealed pontoons, attachable and anchorable onto transversely extending detachable forwardly and rearwardly beams by detachably mountable and anchorable on the transversly extending beams, the band circumscribing the respective inflated pontoons when mounted, at-least a portion of each of the beams extending above the respective pontoons when inflated, the floor being mountable between and detachably anchored on the forwardly and rearwardly beams by forwardly to rearwardly-extending elongated supports extending between and detachably anchored on the forwardly and rearwardly beams, with a wing-rudder mounted in a fixed position on a distal end of an elongated wing-mounting rod-structure of which the proximal rod-end is detachable mounted between the pontoons and anchored on the rearwardly transverse beam, with supplemental support thereto extending from rearward portions of