Abstract: A translucent cover for swimming pools, hothouses and the like comprises, a rigid supporting structure covered by rectangular panels (4) of polycarbonate sheeting. The structure comprises a number of rigid arcuate ribs (1) interconnected in parallel distanced alignment by purlins (2). The ribs are bent into arcuate shape from channels (10) open towards the outside of the cover, each rib having two co-planar flanges (11) extending along both sides of the channel opening. The panels (4) are of a width so as to cover the distance between two adjacent ribs with their two opposite margins resting on the flanges, and are held in position and pressed onto the flanges by means of flexible strips (3). The strips are of a width equal to the distance between the outer edges of the flanges (11) and of a length somewhat shorter than the length of the ribs.