Definitions for "Luffing"
To luff or luff up is to head into the wind causing sails to flutter.
1. When a sailing vessel is steered more to [windward. 2. The flapping of the sails which results. M-R* Mainmast (or Main) - The tallest mast on a ship.
When a sailing boat/ship is steered more towards the direction of the wind. M-R
Keywords:  slewing, jib, pivoted, constant, height
the lowering and raising motion of a jib pivoted at the lower end; when the load is maintained at constant height automatically during luffing, it is known as level luffing compare slewing
Keywords:  derrick, crane, vertical, movement
Vertical movement of a crane or derrick.