Webb, J.2016-04-152016-04-151969-09http://dspace.lib.cranfield.ac.uk/handle/1826/9819This report considers primarily the relatively short cantilever type of inflated matresss beam, currently being employed as sidebody structure on some hovercraft. The rib pitch for optimum stiffness/weight of such beams is determined, and it is shown that thin ribs, closely pitched, with relatively thick skins provide the most efficient structures.enReport