A composite deck assembly includes a baseplate and a top plate secured to the baseplate. The baseplate is formed from a first composite matrix comprising strands of reinforcing fibers oriented in first direction and a polymer resin. The baseplate includes a plurality of ribs and a plurality of laterally extending open channels disposed between the ribs. The top plate is formed from a second composite matrix of reinforcing fibers in a polymer resin, and is secured, optionally releasably, to the baseplate so as to generally enclose at least a portion of the channels. All the reinforcing fibers in the baseplate may be limited to being either the strands oriented in the first direction or matted reinforcing fibers having a random orientation. At least one of the base section and the top plate may be translucent. The open channel configuration simplifies manufacture and lowers cost.