Trawls are nets made into a cone or funnel shape by using shaped net panels. Generally the sides of the net are extended forwards (the wings) to guide fish into the mouth of the net. The end of the net forms a bag or cod-end, into which the fish are gathered.
During trawling the horizontal opening of the net (spread) is maintained by trawl or v-doors, or by the distance between two towing vessels when pair trawling. Floats and weights attached to the leading edges of the top and bottom panels (headline and footrope) of the trawl provide the vertical opening.
Winches installed on deck control and store the wires or warps. These, together with auxiliary winches, net drums and power blocks are to handle, shoot and haul the trawl gear.