A toy airboat (10) having a negative trim element (38) and an adjustable positive trim element (44) for selectively controlling the performance of the craft in varying environmental conditions such as wind speeds and wave heights. The negative trim element may be smoothly curved protrusions (40) formed integral to the hull (12) in order to avoid snagging debris in water and to allow operation over land without damage to the hull. The protrusions may be symmetrically located on opposed sides of a centerline (CL) of the craft approximately midway between the centerline and a perimeter (16) of the hull. The adjustable positive trim element may be a bolt (46) threaded into a nut (48) affixed to a deck (14) of the craft. The nut extends to make contact with the hull to impart a desired degree of convex curvature to the otherwise generally flat bottom of the hull. The bolt may be attached to the hull with a push/pull mechanism (54) to allow the nut alternatively to impart a desired degree of concave curvature to the hull.