Abstract: A pontoon device with mechanisms for varying the width comprising a floor having parallel side edges and front and rear edges; pontoons positionable with respect to the floor with the axes of the pontoons parallel with the side edges of the floor and located beneath the opposite edges thereof; and adjustment mechanisms to vary the lateral spacing between the pontoons, such adjustment mechanisms including a plurality of rod assemblies secured at their opposite ends to the pontoons beneath the lower surface of the floor, each rod assembly including a pair small linear ribs in axial alignment with their outboard ends secured to a pontoon and with an enlarged tubular member therebetween receiving the inboard ends of the ribs in sliding relationship therewith.