A jib is  the forward most triangular sail on a ship. Luffing is a nautical term for when the sail flutters because it is pointed straight into the wind instead of catching it. A luffing jib also refers to a type of crane that is used in tight areas, usually in urban environments. This crane can operate so that its boom is able to be maneuvered in smaller areas so that neighboring property owners do not need to be contacted for permission to operate.