Abstract: The invention concerns low density multichannel structures made of composites, processes and semifinished products for the manufacture thereof.A multichannel laminated resin structure according to the invention includes cellular fabric (1) defining a row of parallel ducts in each of which is inserted a fitted tubular extrusion (3). The semifinished product is placed between the external reinforcement layers (4, 5). The cellular fabric and reinforcement layers are embedded in a curable resin (6).One application is the manufacture of boat hulls or airframes for light aircraft, noncorrodible and very good mechanical properties.