Abstract: A signalling device for indicating the position of a boat or person in the water comprising a bouyant member adapted to be attached to the boat or person and being of a color contrasting with that of the sea, characterized in that the buoyant member is formed of a length of plastic sheeting which has a specific gravity of less than 1 and which is capable of being rolled or folded to occupy a small space for storage or transport, and in that the free end thereof is provided with means such as a sea anchor so that when in use it will stream away from the boat or person.