Luffing is a sailing term which references the behavior of a sail when it is turned into the wind. As the sail flaps, it starts to make a snapping or luffing sound which is very distinctive and easy to identify. In some cases, a sail luffs by accident, and in other cases, it may occur as part of a deliberate maneuver. The term “luffing” is also sometimes used in reference to kites and other types of flexible airfoils which also may luff as they move through the air.
There are several reasons for a sail to luff. One is improper sailing technique, in which someone is not handling the sail correctly. In this case, the luffing can be a prelude to losing control of the boat. In other cases, luffing sometimes occurs while a ship is tacking or under a similar maneuver which is designed to control direction or angle of approach.
In addition to being audible, this phenomenon is also visible as the sail flaps in the wind. It can be a good idea to steer clear of a boat with a luffing sail, because it may be attempting to maneuver. As a general rule, more clearance is always better when it is available, because conditions at sea can get unpredictable, and leaving enough room for everyone to navigate safely can reduce the risk of accidents and other problems.
The term “luffing” also appears in reference to a particular type of crane, a luffing jib crane. These cranes are designed to work in compact quarters, a common problem encountered at building sites in urban areas. Using this style crane also allows people to skirt regional regulations which require crane operators to seek permission before swinging a crane over neighboring land. With a luffing jib crane, the crane can be operated in such a way that it does not pass over land belonging to the neighbors, thereby avoiding the need to comply with such regulations.
This crane design is actually an attachment which can be fitted to an existing crane, rather than an whole crane design. People can purchase the attachment to swap out on an existing crane, or they can order a crane with a luffing jib attachment from a manufacturer, depending on their needs. These cranes are available for lease or rental, for people who need a crane for a short period of time and would rather not buy one.