Abstract: A float system comprised of modular units assembled to form relatively rigid floating assemblies in a plurality of configurations is provided. In a preferred embodiment comprising a basic two-tier assembly, the modular units form upper and lower layers which combine to define a buoyant, protected shell. The units are preferably interchangeable so that they may be used for either the upper or lower layer and are assembled in a staggered manner to form overlapping connections. The modular units may be assembled using a buoyant lower layer and a non-buoyant upper layer, or using more than two buoyant layers if desired. Preferred embodiments for unevenly loaded structures include multilayer portions at locations on the structure corresponding to increased loads.

Abstract: A non-return valve element comprises a one piece moulding of resilient rubber material, for example a synthetic rubber, which is shaped to include a relatively thick and hence rigid planar rib 1 of which the upper edge 1a includes a cylindrical protuberance 2 forming a reinforcement against longitudinal and transverse deflections. The lower edge 1b of the rib has two integral laterally extending wings 3 and 4, each of which is semi-circular in plan. The wings together in planform are circular and are designed to fit a cylindrical bore 5 provided in a fluid flow channel. The bore 5 is delimited from a narrower cross-section bore 6 by means of a shoulder 7 forming a seating for the wings 3 and 4, and an abutment for the ends 8 and 9 of the edge 1b of the rib 1.